diff --git a/src/include/units/si/length.h b/src/include/units/si/length.h
index 9487657b..e4ce39e6 100644
--- a/src/include/units/si/length.h
+++ b/src/include/units/si/length.h
@@ -30,6 +30,7 @@ namespace units {
   using dimension_length = make_dimension_t<exp<base_dim_length, 1>>;
 
   using millimeter = unit<dimension_length, std::milli>;
+  using centimeter = unit<dimension_length, std::ratio<1, 100>>;
   using meter = unit<dimension_length, std::ratio<1>>;
   using kilometer = unit<dimension_length, std::kilo>;
 
@@ -55,6 +56,10 @@ namespace units {
     constexpr auto operator""_mm(unsigned long long l) { return length<millimeter, std::int64_t>(l); }
     constexpr auto operator""_mm(long double l) { return length<millimeter, long double>(l); }
 
+    // cm
+    constexpr auto operator""_cm(unsigned long long l) { return length<centimeter, std::int64_t>(l); }
+    constexpr auto operator""_cm(long double l) { return length<centimeter, long double>(l); }
+
     // m
     constexpr auto operator""_m(unsigned long long l) { return length<meter, std::int64_t>(l); }
     constexpr auto operator""_m(long double l) { return length<meter, long double>(l); }
diff --git a/test/test_units.cpp b/test/test_units.cpp
index 29c352cf..101561cb 100644
--- a/test/test_units.cpp
+++ b/test/test_units.cpp
@@ -48,6 +48,8 @@ namespace {
   static_assert(10_km / 5_km == 2);
   static_assert(10_km / 2 == 5_km);
 
+  static_assert(1_m == 100_cm)//static_assert(5_in + 8_cm == 207_mm);
+
   // velocity
 
   static_assert(std::is_same_v<decltype(1_km / 1_s), velocity<unit<dimension_velocity, std::ratio<1000, 1>>, long long int>>);