diff --git a/src/si/mod.rs b/src/si/mod.rs
index 175cddf6..fb1b7e8d 100644
--- a/src/si/mod.rs
+++ b/src/si/mod.rs
@@ -93,6 +93,7 @@ system! {
         pressure::Pressure,
         radiant_exposure::RadiantExposure,
         ratio::Ratio,
+        reciprocal_length::ReciprocalLength,
         solid_angle::SolidAngle,
         specific_heat_capacity::SpecificHeatCapacity,
         temperature_interval::TemperatureInterval,
diff --git a/src/si/reciprocal_length.rs b/src/si/reciprocal_length.rs
new file mode 100644
index 00000000..0f3fe633
--- /dev/null
+++ b/src/si/reciprocal_length.rs
@@ -0,0 +1,68 @@
+//! Reciprocal length (base unit reciprocal meter, m⁻¹).
+
+quantity! {
+    /// Reciprocal length (base unit reciprocal meter, m⁻¹).
+    quantity: ReciprocalLength; "reciprocal length";
+    /// Dimension of reciprocal length, L⁻¹ (base unit reciprocal meter, m⁻¹).
+    dimension: ISQ<
+        N1,     // length
+        Z0,     // mass
+        Z0,     // time
+        Z0,     // electric current
+        Z0,     // thermodynamic temperature
+        Z0,     // amount of substance
+        Z0>;    // luminous intensity
+    units {
+        @reciprocal_kilometer: prefix!(none) / prefix!(kilo); "km⁻¹",
+            "reciprocal kilometer", "reciprocal kilometers";
+        @reciprocal_meter: prefix!(none); "m⁻¹",
+            "reciprocal meter", "reciprocal meters";
+        @reciprocal_decimeter: prefix!(none) / prefix!(deci); "dm⁻¹",
+            "reciprocal decimeter", "reciprocal decimeters";
+        @reciprocal_centimeter: prefix!(none) / prefix!(centi); "cm⁻¹",
+            "reciprocal centimeter", "reciprocal centimeters";
+        @reciprocal_millimeter: prefix!(none) / prefix!(milli); "mm⁻¹",
+            "reciprocal millimeter", "reciprocal millimeters";     
+        @reciprocal_micrometer: prefix!(none) / prefix!(micro); "µm⁻¹",
+            "reciprocal micrometer", "reciprocal micrometers";   
+        @reciprocal_nanometer: prefix!(none) / prefix!(nano); "nm⁻¹",
+            "reciprocal nanometer", "reciprocal nanometers";
+
+        @reciprocal_angstrom: prefix!(none) / 1.0_E-10; "Å⁻¹",
+            "reciprocal ångström", "reciprocal ångströms";                                         
+    }
+}
+
+#[cfg(test)]
+mod test {
+    storage_types! {
+        use crate::num::One;
+        use crate::si::length as l;
+        use crate::si::reciprocal_length as rl;
+        use crate::si::quantities::*;
+        use crate::tests::Test;
+
+        #[test]
+        fn check_dimension() {
+            let _: ReciprocalLength<V> = V::one()
+                / Length::new::<l::meter>(V::one());
+        }
+
+        #[test]
+        fn check_units() {
+            test::<l::kilometer, rl::reciprocal_kilometer>();
+            test::<l::meter, rl::reciprocal_meter>();
+            test::<l::decimeter, rl::reciprocal_decimeter>();
+            test::<l::centimeter, rl::reciprocal_centimeter>();
+            test::<l::millimeter, rl::reciprocal_millimeter>();
+            test::<l::micrometer, rl::reciprocal_micrometer>();
+            test::<l::nanometer, rl::reciprocal_nanometer>();
+            test::<l::angstrom, rl::reciprocal_angstrom>();
+
+            fn test<L: l::Conversion<V>, RL: rl::Conversion<V>>() {
+                Test::assert_approx_eq(&ReciprocalLength::new::<RL>(V::one()),
+                    &(V::one() / Length::new::<L>(V::one())));
+            }
+        }
+    }
+}