diff --git a/docs/users_guide/framework_basics/dimensionless_quantities.md b/docs/users_guide/framework_basics/dimensionless_quantities.md
index 065e4ae86..3019828fe 100644
--- a/docs/users_guide/framework_basics/dimensionless_quantities.md
+++ b/docs/users_guide/framework_basics/dimensionless_quantities.md
@@ -114,7 +114,7 @@ units of _length_:
 
 ```cpp
 inline constexpr struct hubble_constant :
-    named_unit<{u8"H₀", "H_0"}, mag<ratio{701, 10}> * si::kilo<si::metre> / si::second / si::mega<parsec>> {} hubble_constant;
+    named_unit<{u8"H₀", "H_0"}, mag_ratio<701, 10> * si::kilo<si::metre> / si::second / si::mega<parsec>> {} hubble_constant;
 ```
 
 
@@ -158,9 +158,9 @@ Besides the unit `one`, there are a few other scaled units predefined in the lib
 with dimensionless quantities:
 
 ```cpp
-inline constexpr struct percent : named_unit<"%", mag<ratio{1, 100}> * one> {} percent;
-inline constexpr struct per_mille : named_unit<{u8"‰", "%o"}, mag<ratio(1, 1000)> * one> {} per_mille;
-inline constexpr struct parts_per_million : named_unit<"ppm", mag<ratio(1, 1'000'000)> * one> {} parts_per_million;
+inline constexpr struct percent : named_unit<"%", mag_ratio<1, 100> * one> {} percent;
+inline constexpr struct per_mille : named_unit<{u8"‰", "%o"}, mag_ratio<1, 1000> * one> {} per_mille;
+inline constexpr struct parts_per_million : named_unit<"ppm", mag_ratio<1, 1'000'000> * one> {} parts_per_million;
 inline constexpr auto ppm = parts_per_million;
 ```
 
diff --git a/docs/users_guide/framework_basics/systems_of_units.md b/docs/users_guide/framework_basics/systems_of_units.md
index ef005a373..8f3410236 100644
--- a/docs/users_guide/framework_basics/systems_of_units.md
+++ b/docs/users_guide/framework_basics/systems_of_units.md
@@ -170,14 +170,14 @@ electronvolt:
 ```cpp
 inline constexpr struct minute : named_unit<"min", mag<60> * si::second> {} minute;
 inline constexpr struct hour : named_unit<"h", mag<60> * minute> {} hour;
-inline constexpr struct electronvolt : named_unit<"eV", mag<ratio{1'602'176'634, 1'000'000'000}> * mag_power<10, -19> * si::joule> {} electronvolt;
+inline constexpr struct electronvolt : named_unit<"eV", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * si::joule> {} electronvolt;
 ```
 
 Also, units of other [systems of units](../../appendix/glossary.md#system-of-units) are often defined
 in terms of scaled versions of the SI units. For example, the international yard is defined as:
 
 ```cpp
-inline constexpr struct yard : named_unit<"yd", mag<ratio{9'144, 10'000}> * si::metre> {} yard;
+inline constexpr struct yard : named_unit<"yd", mag_ratio<9'144, 10'000> * si::metre> {} yard;
 ```
 
 For some units, a magnitude might also be irrational. The best example here is a `degree` which
diff --git a/docs/users_guide/framework_basics/text_output.md b/docs/users_guide/framework_basics/text_output.md
index 365b8ece3..dcae732cb 100644
--- a/docs/users_guide/framework_basics/text_output.md
+++ b/docs/users_guide/framework_basics/text_output.md
@@ -77,10 +77,10 @@ and units of derived quantities.
     ```cpp
     inline constexpr struct hyperfine_structure_transition_frequency_of_cs : named_unit<{u8"Δν_Cs", "dv_Cs"}, mag<9'192'631'770> * hertz> {} hyperfine_structure_transition_frequency_of_cs;
     inline constexpr struct speed_of_light_in_vacuum : named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
-    inline constexpr struct planck_constant : named_unit<"h", mag<ratio{662'607'015, 100'000'000}> * mag_power<10, -34> * joule * second> {} planck_constant;
-    inline constexpr struct elementary_charge : named_unit<"e", mag<ratio{1'602'176'634, 1'000'000'000}> * mag_power<10, -19> * coulomb> {} elementary_charge;
-    inline constexpr struct boltzmann_constant : named_unit<"k", mag<ratio{1'380'649, 1'000'000}> * mag_power<10, -23> * joule / kelvin> {} boltzmann_constant;
-    inline constexpr struct avogadro_constant : named_unit<"N_A", mag<ratio{602'214'076, 100'000'000}> * mag_power<10, 23> / mole> {} avogadro_constant;
+    inline constexpr struct planck_constant : named_unit<"h", mag_ratio<662'607'015, 100'000'000> * mag_power<10, -34> * joule * second> {} planck_constant;
+    inline constexpr struct elementary_charge : named_unit<"e", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * coulomb> {} elementary_charge;
+    inline constexpr struct boltzmann_constant : named_unit<"k", mag_ratio<1'380'649, 1'000'000> * mag_power<10, -23> * joule / kelvin> {} boltzmann_constant;
+    inline constexpr struct avogadro_constant : named_unit<"N_A", mag_ratio<602'214'076, 100'000'000> * mag_power<10, 23> / mole> {} avogadro_constant;
     inline constexpr struct luminous_efficacy : named_unit<"K_cd", mag<683> * lumen / watt> {} luminous_efficacy;
     ```
 
diff --git a/docs/users_guide/framework_basics/the_affine_space.md b/docs/users_guide/framework_basics/the_affine_space.md
index ee0def4cd..c672595f2 100644
--- a/docs/users_guide/framework_basics/the_affine_space.md
+++ b/docs/users_guide/framework_basics/the_affine_space.md
@@ -403,7 +403,7 @@ inline constexpr struct zeroth_degree_Celsius : decltype(ice_point) {} zeroth_de
 namespace usc {
 
 inline constexpr struct zeroth_degree_Fahrenheit :
-  relative_point_origin<si::zeroth_degree_Celsius - 32 * (mag<ratio{5, 9}> * si::degree_Celsius)> {} zeroth_degree_Fahrenheit;
+  relative_point_origin<si::zeroth_degree_Celsius - 32 * (mag_ratio<5, 9> * si::degree_Celsius)> {} zeroth_degree_Fahrenheit;
 
 }
 ```
@@ -436,7 +436,7 @@ inline constexpr struct degree_Celsius :
 namespace usc {
 
 inline constexpr struct degree_Fahrenheit :
-    named_unit<{u8"°F", "`F"}, mag<ratio{5, 9}> * si::degree_Celsius,
+    named_unit<{u8"°F", "`F"}, mag_ratio<5, 9> * si::degree_Celsius,
                zeroth_degree_Fahrenheit> {} degree_Fahrenheit;
 
 }
diff --git a/src/core/include/mp-units/bits/expression_template.h b/src/core/include/mp-units/bits/expression_template.h
index 738f66ac5..e6698b254 100644
--- a/src/core/include/mp-units/bits/expression_template.h
+++ b/src/core/include/mp-units/bits/expression_template.h
@@ -99,7 +99,7 @@ template<typename F, int Num, int... Den>
   requires(detail::valid_ratio<Num, Den...> && detail::positive_ratio<Num, Den...> && !detail::ratio_one<Num, Den...>)
 struct power {
   using factor = F;
-  static constexpr ratio exponent{Num, Den...};
+  static constexpr detail::ratio exponent{Num, Den...};
 };
 
 namespace detail {
diff --git a/src/core/include/mp-units/bits/magnitude.h b/src/core/include/mp-units/bits/magnitude.h
index cc9bef1d6..9a3f1cb18 100644
--- a/src/core/include/mp-units/bits/magnitude.h
+++ b/src/core/include/mp-units/bits/magnitude.h
@@ -166,7 +166,7 @@ template<PowerVBase auto V, int Num, int... Den>
   requires(detail::valid_ratio<Num, Den...> && !detail::ratio_one<Num, Den...>)
 struct power_v {
   static constexpr auto base = V;
-  static constexpr ratio exponent{Num, Den...};
+  static constexpr detail::ratio exponent{Num, Den...};
 };
 
 namespace detail {
@@ -565,7 +565,8 @@ template<std::intmax_t Num, std::intmax_t Den = 1, auto... Ms>
   if constexpr (Num == 0) {
     return magnitude<>{};
   } else {
-    return magnitude<detail::power_v_or_T<detail::get_base(Ms), detail::get_exponent(Ms) * ratio{Num, Den}>()...>{};
+    return magnitude<
+      detail::power_v_or_T<detail::get_base(Ms), detail::get_exponent(Ms) * detail::ratio{Num, Den}>()...>{};
   }
 }
 
@@ -675,8 +676,6 @@ template<auto M>
   }
 }
 
-}  // namespace detail
-
 template<auto... Ms>
 [[nodiscard]] consteval auto numerator(magnitude<Ms...>)
 {
@@ -685,8 +684,8 @@ template<auto... Ms>
 
 [[nodiscard]] consteval auto denominator(Magnitude auto m) { return numerator(pow<-1>(m)); }
 
-// Implementation of conversion to ratio goes here, because it needs `numerator()` and `denominator()`.
-constexpr ratio as_ratio(Magnitude auto m)
+// TODO This probably should not be exported but is used in chrono.h
+MP_UNITS_EXPORT constexpr ratio as_ratio(Magnitude auto m)
   requires(is_rational(decltype(m){}))
 {
   return ratio{
@@ -695,7 +694,6 @@ constexpr ratio as_ratio(Magnitude auto m)
   };
 }
 
-
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 // Common Magnitude.
 //
@@ -714,8 +712,6 @@ constexpr ratio as_ratio(Magnitude auto m)
 // Thus, we make the _simplest_ choice which reproduces the correct convention in the rational case: namely, taking the
 // minimum power for each base (where absent bases implicitly have a power of 0).
 
-namespace detail {
-
 template<auto M>
 [[nodiscard]] consteval auto remove_positive_power(magnitude<M> m)
 {
@@ -830,16 +826,20 @@ inline constexpr auto prime_factorization_v = prime_factorization<N>::value;
  * This will be the main way end users create Magnitudes.  They should rarely (if ever) create a magnitude<...> by
  * manually adding base powers.
  */
-MP_UNITS_EXPORT template<ratio R>
-  requires detail::gt_zero<R.num>
-inline constexpr Magnitude auto mag = detail::prime_factorization_v<R.num> / detail::prime_factorization_v<R.den>;
+MP_UNITS_EXPORT template<std::intmax_t V>
+  requires detail::gt_zero<V>
+inline constexpr Magnitude auto mag = detail::prime_factorization_v<V>;
+
+MP_UNITS_EXPORT template<std::intmax_t N, std::intmax_t D>
+  requires detail::gt_zero<N>
+inline constexpr Magnitude auto mag_ratio = detail::prime_factorization_v<N> / detail::prime_factorization_v<D>;
 
 /**
  * @brief  Create a Magnitude which is some rational number raised to a rational power.
  */
-MP_UNITS_EXPORT template<ratio Base, ratio Pow>
-  requires detail::gt_zero<Base.num>
-inline constexpr Magnitude auto mag_power = pow<Pow.num, Pow.den>(mag<Base>);
+MP_UNITS_EXPORT template<std::intmax_t Base, std::intmax_t Pow>
+  requires detail::gt_zero<Base>
+inline constexpr Magnitude auto mag_power = pow<Pow>(mag<Base>);
 
 namespace detail {
 
diff --git a/src/core/include/mp-units/bits/ratio.h b/src/core/include/mp-units/bits/ratio.h
index d7d020f13..8ca88b585 100644
--- a/src/core/include/mp-units/bits/ratio.h
+++ b/src/core/include/mp-units/bits/ratio.h
@@ -32,9 +32,7 @@
 #include <numeric>
 #endif
 
-namespace mp_units {
-
-namespace detail {
+namespace mp_units::detail {
 
 template<typename T>
 [[nodiscard]] MP_UNITS_CONSTEVAL T abs(T v) noexcept
@@ -59,14 +57,13 @@ template<typename T>
   return lhs * rhs;
 }
 
-}  // namespace detail
-
 /**
  * @brief Provides compile-time rational arithmetic support.
  *
  * This class is really similar to @c std::ratio.  An important difference is the fact that the objects of that class
  * are used as class NTTPs rather then a type template parameter kind.
  */
+// TODO This probably should not be exported but is used in chrono.h
 MP_UNITS_EXPORT struct ratio {
   std::intmax_t num;
   std::intmax_t den;
@@ -123,4 +120,4 @@ MP_UNITS_EXPORT struct ratio {
   return ratio{num / gcd, den / gcd};
 }
 
-}  // namespace mp_units
+}  // namespace mp_units::detail
diff --git a/src/core/include/mp-units/math.h b/src/core/include/mp-units/math.h
index ab4f4ae04..cbd6bc2bc 100644
--- a/src/core/include/mp-units/math.h
+++ b/src/core/include/mp-units/math.h
@@ -56,7 +56,7 @@ template<std::intmax_t Num, std::intmax_t Den = 1, auto R, typename Rep>
 {
   if constexpr (Num == 0) {
     return quantity<pow<Num, Den>(R), Rep>::one();
-  } else if constexpr (ratio{Num, Den} == 1) {
+  } else if constexpr (Num == Den) {
     return q;
   } else {
     using std::pow;
diff --git a/src/core/include/mp-units/quantity_spec.h b/src/core/include/mp-units/quantity_spec.h
index 8539cf5fa..a43c03ade 100644
--- a/src/core/include/mp-units/quantity_spec.h
+++ b/src/core/include/mp-units/quantity_spec.h
@@ -555,7 +555,7 @@ template<std::intmax_t Num, std::intmax_t Den = 1, QuantitySpec Q>
   // all are dimensionless quantities :-(
   if constexpr (Num == 0 || Q{} == dimensionless)
     return dimensionless;
-  else if constexpr (ratio{Num, Den} == 1)
+  else if constexpr (detail::ratio{Num, Den} == 1)
     return q;
   else if constexpr (detail::IntermediateDerivedQuantitySpec<Q>)
     return detail::clone_kind_of<Q{}>(
diff --git a/src/core/include/mp-units/unit.h b/src/core/include/mp-units/unit.h
index abca45aca..703bd019f 100644
--- a/src/core/include/mp-units/unit.h
+++ b/src/core/include/mp-units/unit.h
@@ -566,7 +566,7 @@ template<std::intmax_t Num, std::intmax_t Den = 1, Unit U>
 {
   if constexpr (Num == 0 || is_same_v<U, struct one>)
     return one;
-  else if constexpr (ratio{Num, Den} == 1)
+  else if constexpr (detail::ratio{Num, Den} == 1)
     return u;
   else if constexpr (detail::is_specialization_of_scaled_unit<U>)
     return scaled_unit<pow<Num, Den>(U::mag), std::remove_const_t<decltype(pow<Num, Den>(U::reference_unit))>>{};
@@ -617,9 +617,9 @@ template<std::intmax_t Num, std::intmax_t Den = 1, Unit U>
 
 // common dimensionless units
 // clang-format off
-inline constexpr struct percent : named_unit<"%", mag<ratio{1, 100}> * one> {} percent;
-inline constexpr struct per_mille : named_unit<symbol_text{u8"‰", "%o"}, mag<ratio(1, 1000)> * one> {} per_mille;
-inline constexpr struct parts_per_million : named_unit<"ppm", mag<ratio(1, 1'000'000)> * one> {} parts_per_million;
+inline constexpr struct percent : named_unit<"%", mag_ratio<1, 100> * one> {} percent;
+inline constexpr struct per_mille : named_unit<symbol_text{u8"‰", "%o"}, mag_ratio<1, 1000> * one> {} per_mille;
+inline constexpr struct parts_per_million : named_unit<"ppm", mag_ratio<1, 1'000'000> * one> {} parts_per_million;
 inline constexpr auto ppm = parts_per_million;
 // clang-format on
 
diff --git a/src/systems/include/mp-units/systems/angular/units.h b/src/systems/include/mp-units/systems/angular/units.h
index 3f819eb21..0ca22c774 100644
--- a/src/systems/include/mp-units/systems/angular/units.h
+++ b/src/systems/include/mp-units/systems/angular/units.h
@@ -40,8 +40,8 @@ QUANTITY_SPEC(solid_angle, pow<2>(angle));
 
 inline constexpr struct radian : named_unit<"rad", kind_of<angle>> {} radian;
 inline constexpr struct revolution : named_unit<"rev", mag<2> * mag_pi * radian> {} revolution;
-inline constexpr struct degree : named_unit<symbol_text{u8"°", "deg"}, mag<ratio{1, 360}> * revolution> {} degree;
-inline constexpr struct gradian : named_unit<symbol_text{u8"ᵍ", "grad"}, mag<ratio{1, 400}> * revolution> {} gradian;
+inline constexpr struct degree : named_unit<symbol_text{u8"°", "deg"}, mag_ratio<1, 360> * revolution> {} degree;
+inline constexpr struct gradian : named_unit<symbol_text{u8"ᵍ", "grad"}, mag_ratio<1, 400> * revolution> {} gradian;
 inline constexpr struct steradian : named_unit<"sr", square(radian)> {} steradian;
 // clang-format on
 
diff --git a/src/systems/include/mp-units/systems/hep/hep.h b/src/systems/include/mp-units/systems/hep/hep.h
index 616617926..024b39344 100644
--- a/src/systems/include/mp-units/systems/hep/hep.h
+++ b/src/systems/include/mp-units/systems/hep/hep.h
@@ -49,9 +49,9 @@ using si::electronvolt;
 inline constexpr struct barn : named_unit<"b", mag_power<10, -28> * square(si::metre)> {} barn;
 
 // mass
-inline constexpr struct electron_mass : named_unit<"m_e", mag<ratio{9'109'383'701'528, 1'000'000'000'000}> * mag_power<10, -31> * si::kilogram> {} electron_mass;
-inline constexpr struct proton_mass : named_unit<"m_p", mag<ratio{1'672'621'923'695, 1'000'000'000'000}> * mag_power<10, -27> * si::kilogram> {} proton_mass;
-inline constexpr struct neutron_mass : named_unit<"m_n", mag<ratio{1'674'927'498'049, 1'000'000'000'000}> * mag_power<10, -27> * si::kilogram> {} neutron_mass;
+inline constexpr struct electron_mass : named_unit<"m_e", mag_ratio<9'109'383'701'528, 1'000'000'000'000> * mag_power<10, -31> * si::kilogram> {} electron_mass;
+inline constexpr struct proton_mass : named_unit<"m_p", mag_ratio<1'672'621'923'695, 1'000'000'000'000> * mag_power<10, -27> * si::kilogram> {} proton_mass;
+inline constexpr struct neutron_mass : named_unit<"m_n", mag_ratio<1'674'927'498'049, 1'000'000'000'000> * mag_power<10, -27> * si::kilogram> {} neutron_mass;
 
 // speed
 inline constexpr struct speed_of_light : decltype(si::si2019::speed_of_light_in_vacuum) {} speed_of_light;
diff --git a/src/systems/include/mp-units/systems/iau/iau.h b/src/systems/include/mp-units/systems/iau/iau.h
index 34d8c9d0e..bc4c50aa0 100644
--- a/src/systems/include/mp-units/systems/iau/iau.h
+++ b/src/systems/include/mp-units/systems/iau/iau.h
@@ -38,14 +38,14 @@ namespace mp_units::iau {
 // clang-format off
 // time
 inline constexpr struct day : named_unit<"D", si::day> {} day;
-inline constexpr struct Julian_year : named_unit<"a", mag<ratio{365'25, 100}> * day> {} Julian_year;
+inline constexpr struct Julian_year : named_unit<"a", mag_ratio<365'25, 100> * day> {} Julian_year;
 
 // mass
 // https://en.wikipedia.org/wiki/Solar_mass
 // TODO What is the official mass of sun (every source in the Internet provides a different value)
-inline constexpr struct solar_mass : named_unit<symbol_text{u8"M_☉", "M_SUN"}, mag<ratio{198'847, 100'000}> * mag_power<10, 30> * si::kilogram> {} solar_mass;
-inline constexpr struct Jupiter_mass : named_unit<"M_JUP", mag<ratio{1'898, 1'000}> * mag_power<10, 27> * si::kilogram> {} Jupiter_mass;
-inline constexpr struct Earth_mass : named_unit<"M_EARTH", mag<ratio{59'742, 10'000}> * mag_power<10, 24> * si::kilogram> {} Earth_mass;
+inline constexpr struct solar_mass : named_unit<symbol_text{u8"M_☉", "M_SUN"}, mag_ratio<198'847, 100'000> * mag_power<10, 30> * si::kilogram> {} solar_mass;
+inline constexpr struct Jupiter_mass : named_unit<"M_JUP", mag_ratio<1'898, 1'000> * mag_power<10, 27> * si::kilogram> {} Jupiter_mass;
+inline constexpr struct Earth_mass : named_unit<"M_EARTH", mag_ratio<59'742, 10'000> * mag_power<10, 24> * si::kilogram> {} Earth_mass;
 
 // length
 inline constexpr struct astronomical_unit : decltype(si::astronomical_unit) {} astronomical_unit;
@@ -57,7 +57,7 @@ inline constexpr struct lunar_distance : named_unit<"LD", mag<384'399> * si::kil
 inline constexpr struct light_year : named_unit<"ly", mag<9'460'730'472'580'800> * si::metre> {} light_year;
 
 // https://en.wikipedia.org/wiki/Parsec
-inline constexpr struct parsec : named_unit<"pc", astronomical_unit / (mag<ratio{1, 60 * 60}> * si::degree)> {} parsec;
+inline constexpr struct parsec : named_unit<"pc", astronomical_unit / (mag_ratio<1, 60 * 60> * si::degree)> {} parsec;
 
 // https://en.wikipedia.org/wiki/Angstrom
 inline constexpr struct angstrom : named_unit<symbol_text{u8"Å", "A"}, mag_power<10, -10> * si::metre> {} angstrom;
@@ -65,16 +65,16 @@ inline constexpr struct angstrom : named_unit<symbol_text{u8"Å", "A"}, mag_powe
 // selected constants
 // https://en.wikipedia.org/wiki/Astronomical_constant
 inline constexpr struct gaussian_gravitational_constant :
-    named_unit<"k", mag<ratio{1'720'209'895, 100'000'000'000}> * pow<3, 2>(astronomical_unit) / pow<1,2>(solar_mass) / day> {} gaussian_gravitational_constant;
+    named_unit<"k", mag_ratio<1'720'209'895, 100'000'000'000> * pow<3, 2>(astronomical_unit) / pow<1,2>(solar_mass) / day> {} gaussian_gravitational_constant;
 
 inline constexpr struct speed_of_light :
     named_unit<symbol_text{u8"c₀", "c_0"}, si::si2019::speed_of_light_in_vacuum> {} speed_of_light;
 
 inline constexpr struct constant_of_gravitation :
-    named_unit<"G", mag<ratio{667'430, 100'000}> * mag_power<10, -11> * cubic(si::metre) / si::kilogram / square(si::second)> {} constant_of_gravitation;
+    named_unit<"G", mag_ratio<667'430, 100'000> * mag_power<10, -11> * cubic(si::metre) / si::kilogram / square(si::second)> {} constant_of_gravitation;
 
 inline constexpr struct hubble_constant :
-    named_unit<symbol_text{u8"H₀", "H_0"}, mag<ratio{701, 10}> * si::kilo<si::metre> / si::second / si::mega<parsec>> {} hubble_constant;
+    named_unit<symbol_text{u8"H₀", "H_0"}, mag_ratio<701, 10> * si::kilo<si::metre> / si::second / si::mega<parsec>> {} hubble_constant;
 // clang-format on
 
 namespace unit_symbols {
diff --git a/src/systems/include/mp-units/systems/imperial/imperial.h b/src/systems/include/mp-units/systems/imperial/imperial.h
index 52bcae3bf..0b21434e7 100644
--- a/src/systems/include/mp-units/systems/imperial/imperial.h
+++ b/src/systems/include/mp-units/systems/imperial/imperial.h
@@ -36,18 +36,18 @@ using namespace international;
 
 // clang-format off
 // https://en.wikipedia.org/wiki/Imperial_units#Length
-inline constexpr struct hand : named_unit<"hh", mag<ratio{1, 3}> * foot> {} hand;
-inline constexpr struct barleycorn : named_unit<"Bc", mag<ratio(1, 3)> * inch> {} barleycorn;
-inline constexpr struct thou : named_unit<"th", mag<ratio{1, 12'000}> * foot> {} thou;
+inline constexpr struct hand : named_unit<"hh", mag_ratio<1, 3> * foot> {} hand;
+inline constexpr struct barleycorn : named_unit<"Bc", mag_ratio<1, 3> * inch> {} barleycorn;
+inline constexpr struct thou : named_unit<"th", mag_ratio<1, 12'000> * foot> {} thou;
 inline constexpr struct chain : named_unit<"ch", mag<22> * yard> {} chain;
 inline constexpr struct furlong : named_unit<"fur", mag<10> * chain> {} furlong;
 
 // maritime units
-inline constexpr struct cable : named_unit<"cb", mag<ratio{1, 10}> * nautical_mile> {} cable;
-inline constexpr struct fathom : named_unit<"ftm", mag<ratio{1, 1000}> * nautical_mile> {} fathom;
+inline constexpr struct cable : named_unit<"cb", mag_ratio<1, 10> * nautical_mile> {} cable;
+inline constexpr struct fathom : named_unit<"ftm", mag_ratio<1, 1000> * nautical_mile> {} fathom;
 
 // survey
-inline constexpr struct link : named_unit<"li", mag<ratio{1, 100}> * chain> {} link;
+inline constexpr struct link : named_unit<"li", mag_ratio<1, 100> * chain> {} link;
 inline constexpr struct rod : named_unit<"rd", mag<25> * link> {} rod;
 
 // https://en.wikipedia.org/wiki/Imperial_units#Area
@@ -56,11 +56,11 @@ inline constexpr struct rood : decltype(mag<40> * perch) {} rood;
 inline constexpr struct acre : decltype(mag<4> * rood) {} acre;
 
 // https://en.wikipedia.org/wiki/Imperial_units#Volume
-inline constexpr struct gallon : named_unit<"gal", mag<ratio{454'609, 100'000}> * si::litre> {} gallon;
-inline constexpr struct quart : named_unit<"qt", mag<ratio{1, 4}> * gallon> {} quart;
-inline constexpr struct pint : named_unit<"pt", mag<ratio{1, 2}> * quart> {} pint;
-inline constexpr struct gill : named_unit<"gi", mag<ratio{1, 4}> * pint> {} gill;
-inline constexpr struct fluid_ounce : named_unit<"fl oz", mag<ratio{1, 5}> * gill> {} fluid_ounce;
+inline constexpr struct gallon : named_unit<"gal", mag_ratio<454'609, 100'000> * si::litre> {} gallon;
+inline constexpr struct quart : named_unit<"qt", mag_ratio<1, 4> * gallon> {} quart;
+inline constexpr struct pint : named_unit<"pt", mag_ratio<1, 2> * quart> {} pint;
+inline constexpr struct gill : named_unit<"gi", mag_ratio<1, 4> * pint> {} gill;
+inline constexpr struct fluid_ounce : named_unit<"fl oz", mag_ratio<1, 5> * gill> {} fluid_ounce;
 
 // https://en.wikipedia.org/wiki/Avoirdupois_system#Post-Elizabethan_units
 inline constexpr auto drachm = dram;
diff --git a/src/systems/include/mp-units/systems/international/international.h b/src/systems/include/mp-units/systems/international/international.h
index e49b3293f..ba37696fa 100644
--- a/src/systems/include/mp-units/systems/international/international.h
+++ b/src/systems/include/mp-units/systems/international/international.h
@@ -35,20 +35,20 @@ namespace mp_units::international {
 
 // clang-format off
 // mass
-inline constexpr struct pound : named_unit<"lb", mag<ratio{45'359'237, 100'000'000}> * si::kilogram> {} pound;
-inline constexpr struct ounce : named_unit<"oz", mag<ratio(1, 16)> * pound> {} ounce;
-inline constexpr struct dram : named_unit<"dr", mag<ratio(1, 16)> * ounce> {} dram;
-inline constexpr struct grain : named_unit<"gr", mag<ratio(1, 7'000)> * pound> {} grain;
+inline constexpr struct pound : named_unit<"lb", mag_ratio<45'359'237, 100'000'000> * si::kilogram> {} pound;
+inline constexpr struct ounce : named_unit<"oz", mag_ratio<1, 16> * pound> {} ounce;
+inline constexpr struct dram : named_unit<"dr", mag_ratio<1, 16> * ounce> {} dram;
+inline constexpr struct grain : named_unit<"gr", mag_ratio<1, 7'000> * pound> {} grain;
 
 // length
 // https://en.wikipedia.org/wiki/United_States_customary_units#Length
-inline constexpr struct yard : named_unit<"yd", mag<ratio{9'144, 10'000}> * si::metre> {} yard;
-inline constexpr struct foot : named_unit<"ft", mag<ratio{1, 3}> * yard> {} foot;
-inline constexpr struct inch : named_unit<"in", mag<ratio{1, 12}> * foot> {} inch;
-inline constexpr struct pica : named_unit<"P", mag<ratio{1, 6}> * inch> {} pica;
-inline constexpr struct point : named_unit<"p", mag<ratio{1, 12}> * pica> {} point;
-inline constexpr struct mil : named_unit<"mil", mag<ratio{1, 1'000}> * inch> {} mil;
-inline constexpr struct twip : named_unit<"twip", mag<ratio{1, 20}> * point> {} twip;
+inline constexpr struct yard : named_unit<"yd", mag_ratio<9'144, 10'000> * si::metre> {} yard;
+inline constexpr struct foot : named_unit<"ft", mag_ratio<1, 3> * yard> {} foot;
+inline constexpr struct inch : named_unit<"in", mag_ratio<1, 12> * foot> {} inch;
+inline constexpr struct pica : named_unit<"P", mag_ratio<1, 6> * inch> {} pica;
+inline constexpr struct point : named_unit<"p", mag_ratio<1, 12> * pica> {} point;
+inline constexpr struct mil : named_unit<"mil", mag_ratio<1, 1'000> * inch> {} mil;
+inline constexpr struct twip : named_unit<"twip", mag_ratio<1, 20> * point> {} twip;
 inline constexpr struct mile : named_unit<"mi", mag<1760> * yard> {} mile;
 inline constexpr struct league : named_unit<"le", mag<3> * mile> {} league;
 
diff --git a/src/systems/include/mp-units/systems/si/chrono.h b/src/systems/include/mp-units/systems/si/chrono.h
index 80bdc003d..ed51d736a 100644
--- a/src/systems/include/mp-units/systems/si/chrono.h
+++ b/src/systems/include/mp-units/systems/si/chrono.h
@@ -59,7 +59,7 @@ template<typename Period>
   else if constexpr (is_same_v<Period, std::chrono::weeks::period>)
     return mag<7> * day;
   else
-    return mag<ratio{Period::num, Period::den}> * second;
+    return mag_ratio<Period::num, Period::den> * second;
 }
 
 }  // namespace detail
@@ -115,7 +115,7 @@ template<QuantityOf<isq::time> Q>
 [[nodiscard]] constexpr auto to_chrono_duration(const Q& q)
 {
   constexpr auto canonical = get_canonical_unit(Q::unit);
-  constexpr ratio r = as_ratio(canonical.mag);
+  constexpr detail::ratio r = detail::as_ratio(canonical.mag);
   return std::chrono::duration<typename Q::rep, std::ratio<r.num, r.den>>{q};
 }
 
@@ -126,7 +126,7 @@ template<QuantityPointOf<isq::time> QP>
   using clock = MP_UNITS_TYPENAME decltype(QP::absolute_point_origin)::clock;
   using rep = MP_UNITS_TYPENAME QP::rep;
   constexpr auto canonical = get_canonical_unit(QP::unit);
-  constexpr ratio r = as_ratio(canonical.mag);
+  constexpr detail::ratio r = detail::as_ratio(canonical.mag);
   using ret_type = std::chrono::time_point<clock, std::chrono::duration<rep, std::ratio<r.num, r.den>>>;
   return ret_type(to_chrono_duration(qp - qp.absolute_point_origin));
 }
diff --git a/src/systems/include/mp-units/systems/si/constants.h b/src/systems/include/mp-units/systems/si/constants.h
index 012e2cf4b..87ad40127 100644
--- a/src/systems/include/mp-units/systems/si/constants.h
+++ b/src/systems/include/mp-units/systems/si/constants.h
@@ -40,13 +40,13 @@ inline constexpr struct hyperfine_structure_transition_frequency_of_cs :
 inline constexpr struct speed_of_light_in_vacuum :
   named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
 inline constexpr struct planck_constant :
-  named_unit<"h", mag<ratio{662'607'015, 100'000'000}> * mag_power<10, -34> * joule * second> {} planck_constant;
+  named_unit<"h", mag_ratio<662'607'015, 100'000'000> * mag_power<10, -34> * joule * second> {} planck_constant;
 inline constexpr struct elementary_charge :
-  named_unit<"e", mag<ratio{1'602'176'634, 1'000'000'000}> * mag_power<10, -19> * coulomb> {} elementary_charge;
+  named_unit<"e", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * coulomb> {} elementary_charge;
 inline constexpr struct boltzmann_constant :
-  named_unit<"k", mag<ratio{1'380'649, 1'000'000}> * mag_power<10, -23> * joule / kelvin> {} boltzmann_constant;
+  named_unit<"k", mag_ratio<1'380'649, 1'000'000> * mag_power<10, -23> * joule / kelvin> {} boltzmann_constant;
 inline constexpr struct avogadro_constant :
-  named_unit<"N_A", mag<ratio{602'214'076, 100'000'000}> * mag_power<10, 23> / mole> {} avogadro_constant;
+  named_unit<"N_A", mag_ratio<602'214'076, 100'000'000> * mag_power<10, 23> / mole> {} avogadro_constant;
 inline constexpr struct luminous_efficacy :
   named_unit<"K_cd", mag<683> * lumen / watt> {} luminous_efficacy;
 // clang-format on
@@ -55,7 +55,7 @@ inline constexpr struct luminous_efficacy :
 
 // clang-format off
 inline constexpr struct standard_gravity :
-  named_unit<symbol_text{u8"g₀", "g_0"}, mag<ratio{980'665, 100'000}> * metre / square(second)> {} standard_gravity;
+  named_unit<symbol_text{u8"g₀", "g_0"}, mag_ratio<980'665, 100'000> * metre / square(second)> {} standard_gravity;
 inline constexpr struct magnetic_constant :
   named_unit<symbol_text{u8"μ₀", "u_0"}, mag<4> * mag_pi * mag_power<10, -7> * henry / metre> {} magnetic_constant;
 // clang-format on
diff --git a/src/systems/include/mp-units/systems/si/units.h b/src/systems/include/mp-units/systems/si/units.h
index 7634aae36..360028e0f 100644
--- a/src/systems/include/mp-units/systems/si/units.h
+++ b/src/systems/include/mp-units/systems/si/units.h
@@ -104,8 +104,8 @@ inline constexpr struct hour : named_unit<"h", mag<60> * minute> {} hour;
 inline constexpr struct day : named_unit<"d", mag<24> * hour> {} day;
 inline constexpr struct astronomical_unit : named_unit<"au", mag<149'597'870'700> * si::metre> {} astronomical_unit;
 inline constexpr struct degree : named_unit<symbol_text{u8"°", "deg"}, mag_pi / mag<180> * si::radian> {} degree;
-inline constexpr struct arcminute : named_unit<symbol_text{u8"′", "'"}, mag<ratio{1, 60}> * degree> {} arcminute;
-inline constexpr struct arcsecond : named_unit<symbol_text{u8"″", "''"}, mag<ratio{1, 60}> * arcminute> {} arcsecond;
+inline constexpr struct arcminute : named_unit<symbol_text{u8"′", "'"}, mag_ratio<1, 60> * degree> {} arcminute;
+inline constexpr struct arcsecond : named_unit<symbol_text{u8"″", "''"}, mag_ratio<1, 60> * arcminute> {} arcsecond;
 inline constexpr struct are : named_unit<"a", square(si::deca<si::metre>)> {} are;
 #if MP_UNITS_COMP_MSVC
 inline constexpr struct hectare : si::hecto_<are> {} hectare;
@@ -114,9 +114,9 @@ inline constexpr struct hectare : decltype(si::hecto<are>) {} hectare;
 #endif
 inline constexpr struct litre : named_unit<"l", cubic(si::deci<si::metre>)> {} litre;
 inline constexpr struct tonne : named_unit<"t", mag<1000> * si::kilogram> {} tonne;
-inline constexpr struct dalton : named_unit<"Da", mag<ratio{16'605'390'666'050, 10'000'000'000'000}> * mag_power<10, -27> * si::kilogram> {} dalton;
+inline constexpr struct dalton : named_unit<"Da", mag_ratio<16'605'390'666'050, 10'000'000'000'000> * mag_power<10, -27> * si::kilogram> {} dalton;
 // TODO A different value is provided in the SI Brochure and different in the ISO 80000
-inline constexpr struct electronvolt : named_unit<"eV", mag<ratio{1'602'176'634, 1'000'000'000}> * mag_power<10, -19> * si::joule> {} electronvolt;
+inline constexpr struct electronvolt : named_unit<"eV", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * si::joule> {} electronvolt;
 // TODO the below are logarithmic units - how to support those?
 // neper
 // bel
diff --git a/src/systems/include/mp-units/systems/typographic/typographic.h b/src/systems/include/mp-units/systems/typographic/typographic.h
index 4f076b8c3..82186177a 100644
--- a/src/systems/include/mp-units/systems/typographic/typographic.h
+++ b/src/systems/include/mp-units/systems/typographic/typographic.h
@@ -34,10 +34,10 @@ namespace mp_units::typographic {
 
 // clang-format off
 // https://en.wikipedia.org/wiki/Point_(typography)
-inline constexpr struct pica_us : named_unit<"pica(us)", mag<ratio{166'044, 1'000'000}> * international::inch> {} pica_us;
-inline constexpr struct point_us : named_unit<"point(us)", mag<ratio{1, 12}> * pica_us> {} point_us;
+inline constexpr struct pica_us : named_unit<"pica(us)", mag_ratio<166'044, 1'000'000> * international::inch> {} pica_us;
+inline constexpr struct point_us : named_unit<"point(us)", mag_ratio<1, 12> * pica_us> {} point_us;
 
-inline constexpr struct point_dtp : named_unit<"point(dtp)", mag<ratio{1, 72}> * international::inch> {} point_dtp;
+inline constexpr struct point_dtp : named_unit<"point(dtp)", mag_ratio<1, 72> * international::inch> {} point_dtp;
 inline constexpr struct pica_dtp : named_unit<"pica(dtp)", mag<12> * point_dtp> {} pica_dtp;
 // clang-format on
 
diff --git a/src/systems/include/mp-units/systems/usc/usc.h b/src/systems/include/mp-units/systems/usc/usc.h
index cac1e08af..7a1971fd7 100644
--- a/src/systems/include/mp-units/systems/usc/usc.h
+++ b/src/systems/include/mp-units/systems/usc/usc.h
@@ -42,7 +42,7 @@ inline constexpr struct fathom : named_unit<"ftm(us)", mag<2> * yard> {} fathom;
 inline constexpr struct cable : named_unit<"cb(us)", mag<120> * fathom> {} cable;
 
 // survey
-struct us_survey_foot : named_unit<"ft(us)", mag<ratio{1'200, 3'937}> * si::metre> {};
+struct us_survey_foot : named_unit<"ft(us)", mag_ratio<1'200, 3'937> * si::metre> {};
 struct us_survey_mile : named_unit<"mi(us)", mag<5280> * us_survey_foot{}> {};
 
 [[deprecated("In accordance with NIST SP 811, as of January 1, 2023, the use of the U.S. survey foot and U.S. survey mile is deprecated.")]]
@@ -51,7 +51,7 @@ inline constexpr us_survey_foot us_survey_foot;
 [[deprecated("In accordance with NIST SP 811, as of January 1, 2023, the use of the U.S. survey foot and U.S. survey mile is deprecated.")]]
 inline constexpr us_survey_mile us_survey_mile;
 
-inline constexpr struct link : named_unit<"li", mag<ratio{33, 50}> * foot> {} link;
+inline constexpr struct link : named_unit<"li", mag_ratio<33, 50> * foot> {} link;
 inline constexpr struct rod : named_unit<"rd", mag<25> * link> {} rod;
 inline constexpr struct chain : named_unit<"ch", mag<4> * rod> {} chain;
 inline constexpr struct furlong : named_unit<"fur", mag<10> * chain> {} furlong;
@@ -60,8 +60,8 @@ inline constexpr struct furlong : named_unit<"fur", mag<10> * chain> {} furlong;
 namespace survey1893 {
 
 // clang-format off
-inline constexpr struct us_survey_foot : named_unit<"ft(us)", mag<ratio{1'200, 3'937}> * si::metre> {} us_survey_foot;
-inline constexpr struct link : named_unit<"li", mag<ratio{33, 50}> * us_survey_foot> {} link;
+inline constexpr struct us_survey_foot : named_unit<"ft(us)", mag_ratio<1'200, 3'937> * si::metre> {} us_survey_foot;
+inline constexpr struct link : named_unit<"li", mag_ratio<33, 50> * us_survey_foot> {} link;
 inline constexpr struct rod : named_unit<"rd", mag<25> * link> {} rod;
 inline constexpr struct chain : named_unit<"ch", mag<4> * rod> {} chain;
 inline constexpr struct furlong : named_unit<"fur", mag<10> * chain> {} furlong;
@@ -78,28 +78,28 @@ inline constexpr struct section : named_unit<"section", mag<640> * acre> {} sect
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Fluid_volume
 inline constexpr struct gallon : named_unit<"gal", mag<231> * cubic(inch)> {} gallon;
-inline constexpr struct pottle : named_unit<"pot", mag<ratio{1, 2}> * gallon> {} pottle;
-inline constexpr struct quart : named_unit<"qt", mag<ratio{1, 2}> * pottle> {} quart;
-inline constexpr struct pint : named_unit<"pt", mag<ratio{1, 2}> * quart> {} pint;
-inline constexpr struct cup : named_unit<"c", mag<ratio{1, 2}> * pint> {} cup;
-inline constexpr struct gill : named_unit<"gi", mag<ratio{1, 2}> * cup> {} gill;
-inline constexpr struct fluid_ounce : named_unit<"fl oz", mag<ratio{1, 4}> * gill> {} fluid_ounce;
-inline constexpr struct tablespoon : named_unit<"tbsp", mag<ratio{1, 2}> * fluid_ounce> {} tablespoon;
+inline constexpr struct pottle : named_unit<"pot", mag_ratio<1, 2> * gallon> {} pottle;
+inline constexpr struct quart : named_unit<"qt", mag_ratio<1, 2> * pottle> {} quart;
+inline constexpr struct pint : named_unit<"pt", mag_ratio<1, 2> * quart> {} pint;
+inline constexpr struct cup : named_unit<"c", mag_ratio<1, 2> * pint> {} cup;
+inline constexpr struct gill : named_unit<"gi", mag_ratio<1, 2> * cup> {} gill;
+inline constexpr struct fluid_ounce : named_unit<"fl oz", mag_ratio<1, 4> * gill> {} fluid_ounce;
+inline constexpr struct tablespoon : named_unit<"tbsp", mag_ratio<1, 2> * fluid_ounce> {} tablespoon;
 inline constexpr struct shot : named_unit<"jig", mag<3> * tablespoon> {} shot;
-inline constexpr struct teaspoon : named_unit<"tsp", mag<ratio{1, 3}> * tablespoon> {} teaspoon;
-inline constexpr struct minim : named_unit<"min", mag<ratio{1, 80}> * teaspoon> {} minim;
+inline constexpr struct teaspoon : named_unit<"tsp", mag_ratio<1, 3> * tablespoon> {} teaspoon;
+inline constexpr struct minim : named_unit<"min", mag_ratio<1, 80> * teaspoon> {} minim;
 inline constexpr struct fluid_dram : named_unit<"fl dr", mag<60> * minim> {} fluid_dram;
-inline constexpr struct barrel : named_unit<"bbl", mag<ratio{315, 10}> * gallon> {} barrel;
-inline constexpr struct oil_barrel : named_unit<"bbl", mag<ratio{4, 3}> * barrel> {} oil_barrel;
+inline constexpr struct barrel : named_unit<"bbl", mag_ratio<315, 10> * gallon> {} barrel;
+inline constexpr struct oil_barrel : named_unit<"bbl", mag_ratio<4, 3> * barrel> {} oil_barrel;
 inline constexpr struct hogshead : decltype(mag<63> * gallon) {} hogshead;
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Dry_volume
 inline constexpr struct dry_barrel : named_unit<"bbl", mag<7056> * cubic(inch)> {} dry_barrel;
-inline constexpr struct bushel : named_unit<"bu", mag<ratio{3'523'907'016'688, 100'000'000'000}> * si::litre> {} bushel;
-inline constexpr struct peck : named_unit<"pk", mag<ratio{1, 4}> * bushel> {} peck;
-inline constexpr struct dry_gallon : named_unit<"gal", mag<ratio{1, 2}> * peck> {} dry_gallon;
-inline constexpr struct dry_quart : named_unit<"qt", mag<ratio{1, 4}> * dry_gallon> {} dry_quart;
-inline constexpr struct dry_pint : named_unit<"pt", mag<ratio{1, 2}> * dry_quart> {} dry_pint;
+inline constexpr struct bushel : named_unit<"bu", mag_ratio<3'523'907'016'688, 100'000'000'000> * si::litre> {} bushel;
+inline constexpr struct peck : named_unit<"pk", mag_ratio<1, 4> * bushel> {} peck;
+inline constexpr struct dry_gallon : named_unit<"gal", mag_ratio<1, 2> * peck> {} dry_gallon;
+inline constexpr struct dry_quart : named_unit<"qt", mag_ratio<1, 4> * dry_gallon> {} dry_quart;
+inline constexpr struct dry_pint : named_unit<"pt", mag_ratio<1, 2> * dry_quart> {} dry_pint;
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Mass_and_Weight
 // https://en.wikipedia.org/wiki/Avoirdupois_system#American_customary_system
@@ -112,11 +112,11 @@ inline constexpr struct troy_once : named_unit<"oz t", mag<20> * pennyweight> {}
 inline constexpr struct troy_pound : named_unit<"lb t", mag<12> * troy_once> {} troy_pound;
 
 // https://en.wikipedia.org/wiki/Inch_of_mercury
-inline constexpr struct inch_of_mercury : named_unit<"inHg", mag<ratio(3'386'389, 1'000)> * si::pascal> {} inch_of_mercury;
+inline constexpr struct inch_of_mercury : named_unit<"inHg", mag_ratio<3'386'389, 1'000> * si::pascal> {} inch_of_mercury;
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Temperature
-inline constexpr struct zeroth_degree_Fahrenheit : relative_point_origin<si::zeroth_degree_Celsius - 32 * (mag<ratio{5, 9}> * si::degree_Celsius)> {} zeroth_degree_Fahrenheit;
-inline constexpr struct degree_Fahrenheit : named_unit<symbol_text{u8"°F", "`F"}, mag<ratio{5, 9}> * si::degree_Celsius, zeroth_degree_Fahrenheit> {} degree_Fahrenheit;
+inline constexpr struct zeroth_degree_Fahrenheit : relative_point_origin<si::zeroth_degree_Celsius - 32 * (mag_ratio<5, 9> * si::degree_Celsius)> {} zeroth_degree_Fahrenheit;
+inline constexpr struct degree_Fahrenheit : named_unit<symbol_text{u8"°F", "`F"}, mag_ratio<5, 9> * si::degree_Celsius, zeroth_degree_Fahrenheit> {} degree_Fahrenheit;
 
 // clang-format on
 
diff --git a/test/static/ratio_test.cpp b/test/static/ratio_test.cpp
index 5bf9bec08..0b9b7e6a3 100644
--- a/test/static/ratio_test.cpp
+++ b/test/static/ratio_test.cpp
@@ -24,7 +24,7 @@
 
 namespace {
 
-using namespace mp_units;
+using namespace mp_units::detail;
 
 static_assert(ratio(2, 4) == ratio(1, 2));
 
diff --git a/test/static/si_test.cpp b/test/static/si_test.cpp
index 853d51c4f..566a72d0b 100644
--- a/test/static/si_test.cpp
+++ b/test/static/si_test.cpp
@@ -69,7 +69,7 @@ static_assert(can_not_be_prefixed<si::milli_, si::kilogram>);
 static_assert(can_not_be_prefixed<si::milli_, si::hectare>);
 static_assert(can_not_be_prefixed<si::milli_, si::kilo<si::metre>>);
 static_assert(can_not_be_prefixed<si::milli_, si::metre / si::second>);
-static_assert(can_not_be_prefixed<si::milli_, mag<ratio{1, 60}> * si::degree>);
+static_assert(can_not_be_prefixed<si::milli_, mag_ratio<1, 60> * si::degree>);
 
 // coherent SI units are checked in isq_test.cpp
 
diff --git a/test/static/unit_symbol_test.cpp b/test/static/unit_symbol_test.cpp
index df995d48e..fcbebbdb4 100644
--- a/test/static/unit_symbol_test.cpp
+++ b/test/static/unit_symbol_test.cpp
@@ -107,7 +107,7 @@ static_assert(unit_symbol(mag<100> * metre) == "× 10² m");
 static_assert(unit_symbol<unit_symbol_formatting{.encoding = ascii}>(mag<100> * metre) == "x 10^2 m");
 static_assert(unit_symbol(mag<60> * second) == "[6 × 10¹] s");
 static_assert(unit_symbol<unit_symbol_formatting{.encoding = ascii}>(mag<60> * second) == "[6 x 10^1] s");
-static_assert(unit_symbol(mag<ratio{1, 18}> * metre / second) == "[1/18] m/s");
+static_assert(unit_symbol(mag_ratio<1, 18> * metre / second) == "[1/18] m/s");
 
 // derived units
 static_assert(unit_symbol(one) == "");
diff --git a/test/static/unit_test.cpp b/test/static/unit_test.cpp
index 5fdbda572..590a147fa 100644
--- a/test/static/unit_test.cpp
+++ b/test/static/unit_test.cpp
@@ -73,14 +73,14 @@ inline constexpr struct minute_ : named_unit<"min", mag<60> * second> {} minute;
 inline constexpr struct hour_ : named_unit<"h", mag<60> * minute> {} hour;
 inline constexpr struct degree_ : named_unit<symbol_text{u8"°", "deg"}, mag_pi / mag<180> * radian> {} degree;
 
-inline constexpr struct yard_ : named_unit<"yd", mag<ratio{9'144, 10'000}> * metre> {} yard;
+inline constexpr struct yard_ : named_unit<"yd", mag_ratio<9'144, 10'000> * metre> {} yard;
 inline constexpr struct mile_ : named_unit<"mi", mag<1760> * yard> {} mile;
 
 inline constexpr struct kilometre_ : decltype(si::kilo<metre>) {} kilometre;
 inline constexpr struct kilojoule_ : decltype(si::kilo<joule>) {} kilojoule;
 
 // physical constant units
-inline constexpr struct standard_gravity_ : named_unit<symbol_text{u8"g₀", "g_0"}, mag<ratio{980'665, 100'000}> * metre / square(second)> {} standard_gravity;
+inline constexpr struct standard_gravity_ : named_unit<symbol_text{u8"g₀", "g_0"}, mag_ratio<980'665, 100'000> * metre / square(second)> {} standard_gravity;
 inline constexpr struct speed_of_light_in_vacuum_ : named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
 
 // clang-format on
@@ -185,7 +185,7 @@ static_assert(is_of_type<nu_second / nu_second, one_>);
 static_assert(is_of_type<standard_gravity, standard_gravity_>);
 static_assert(
   is_of_type<get_canonical_unit(standard_gravity).reference_unit, derived_unit<metre_, per<power<second_, 2>>>>);
-static_assert(get_canonical_unit(standard_gravity).mag == mag<ratio{980'665, 100'000}>);
+static_assert(get_canonical_unit(standard_gravity).mag == mag_ratio<980'665, 100'000>);
 static_assert(convertible(standard_gravity, standard_gravity));
 static_assert(convertible(standard_gravity, metre / square(second)));
 static_assert(standard_gravity == standard_gravity);
@@ -356,7 +356,7 @@ static_assert(get_canonical_unit(km_per_s).mag == mag<1000>);
 constexpr auto km_per_h = kilometre / hour;
 static_assert(is_of_type<km_per_h, derived_unit<kilometre_, per<hour_>>>);
 static_assert(is_of_type<get_canonical_unit(km_per_h).reference_unit, derived_unit<metre_, per<second_>>>);
-static_assert(get_canonical_unit(km_per_h).mag == mag<ratio{1000, 3600}>);
+static_assert(get_canonical_unit(km_per_h).mag == mag_ratio<1000, 3600>);
 
 static_assert(is_of_type<get_canonical_unit(inverse(metre)).reference_unit, derived_unit<one_, per<metre_>>>);
 static_assert(is_of_type<get_canonical_unit(inverse(hertz)).reference_unit, second_>);
@@ -368,7 +368,7 @@ static_assert(
 
 static_assert(
   is_of_type<get_canonical_unit(standard_gravity).reference_unit, derived_unit<metre_, per<power<second_, 2>>>>);
-static_assert(get_canonical_unit(standard_gravity).mag == mag<ratio{980'665, 100'000}>);
+static_assert(get_canonical_unit(standard_gravity).mag == mag_ratio<980'665, 100'000>);
 static_assert(is_of_type<get_canonical_unit(standard_gravity* gram).reference_unit,
                          derived_unit<gram_, metre_, per<power<second_, 2>>>>);
 static_assert(is_of_type<get_canonical_unit(standard_gravity / speed_of_light_in_vacuum).reference_unit,
@@ -378,17 +378,17 @@ static_assert(is_of_type<get_canonical_unit(standard_gravity / speed_of_light_in
 constexpr auto u1 = mag<1000> * kilometre / hour;
 static_assert(is_of_type<u1, scaled_unit<mag<1000>, derived_unit<kilometre_, per<hour_>>>>);
 static_assert(is_of_type<get_canonical_unit(u1).reference_unit, derived_unit<metre_, per<second_>>>);
-static_assert(get_canonical_unit(u1).mag == mag<ratio{1'000'000, 3'600}>);
+static_assert(get_canonical_unit(u1).mag == mag_ratio<1'000'000, 3'600>);
 
 constexpr auto u2 = mag<1000> * (kilometre / hour);
 static_assert(is_of_type<u2, scaled_unit<mag<1000>, derived_unit<kilometre_, per<hour_>>>>);
 static_assert(is_of_type<get_canonical_unit(u2).reference_unit, derived_unit<metre_, per<second_>>>);
-static_assert(get_canonical_unit(u2).mag == mag<ratio{1'000'000, 3'600}>);
+static_assert(get_canonical_unit(u2).mag == mag_ratio<1'000'000, 3'600>);
 
 constexpr auto u3 = one / hour * (mag<1000> * kilometre);
 static_assert(is_of_type<u3, scaled_unit<mag<1000>, derived_unit<kilometre_, per<hour_>>>>);
 static_assert(is_of_type<get_canonical_unit(u3).reference_unit, derived_unit<metre_, per<second_>>>);
-static_assert(get_canonical_unit(u3).mag == mag<ratio{1'000'000, 3'600}>);
+static_assert(get_canonical_unit(u3).mag == mag_ratio<1'000'000, 3'600>);
 
 template<auto& s>
 concept invalid_operations = requires {
@@ -448,7 +448,7 @@ static_assert(convertible(si::kilo<metre>, kilometre));
 static_assert(convertible(mag<1000> * metre, si::kilo<metre>));
 static_assert(convertible(mag<1000> * metre, kilometre));
 
-static_assert(mag<60> * metre / second == metre / (mag<ratio{1, 60}> * second));
+static_assert(mag<60> * metre / second == metre / (mag_ratio<1, 60> * second));
 
 static_assert(metre != kilometre);
 static_assert(convertible(metre, kilometre));
@@ -533,11 +533,11 @@ static_assert(is_of_type<common_unit(yard, mile), yard_>);
 static_assert(is_of_type<common_unit(mile, yard), yard_>);
 // TODO The below have long/unreadable magnitude types
 static_assert(is_of_type<common_unit(kilometre / hour, metre / second),
-                         scaled_unit<mag<ratio{1, 18}>, derived_unit<metre_, per<second_>>>>);
+                         scaled_unit<mag_ratio<1, 18>, derived_unit<metre_, per<second_>>>>);
 static_assert(is_of_type<common_unit(metre / second, kilometre / hour),
-                         scaled_unit<mag<ratio{1, 18}>, derived_unit<metre_, per<second_>>>>);
-static_assert(is_of_type<common_unit(kilometre, mile), scaled_unit<mag<ratio{8, 125}>, metre_>>);
-static_assert(is_of_type<common_unit(mile, kilometre), scaled_unit<mag<ratio{8, 125}>, metre_>>);
+                         scaled_unit<mag_ratio<1, 18>, derived_unit<metre_, per<second_>>>>);
+static_assert(is_of_type<common_unit(kilometre, mile), scaled_unit<mag_ratio<8, 125>, metre_>>);
+static_assert(is_of_type<common_unit(mile, kilometre), scaled_unit<mag_ratio<8, 125>, metre_>>);
 static_assert(is_of_type<common_unit(speed_of_light_in_vacuum, metre / second), derived_unit<metre_, per<second_>>>);
 
 }  // namespace