diff --git a/README.md b/README.md
index 42313f7..6b5b644 100644
--- a/README.md
+++ b/README.md
@@ -65,6 +65,7 @@ quat(1.0, 2.0, 3.0, 4.0) ~= quat(1.0, 2.0, 3.0, 4.0)
 * `sign` - Returns the sign of a number, -1 or 1.
 * `quantize` - Makes v be a multiple of n. Rounding to integer quantizes by 1.0.
 * `lerp` - Interpolates value between a and b.
+* `len` - Returns the vector component count or matrix column count.
 * `step` - Returns 0.0 if x is less than edge, otherwise 1.0.
 * `smoothstep` - Performs smooth Hermite interpolation between 0.0 and 1.0.
 
diff --git a/src/vmath.nim b/src/vmath.nim
index 833e2e3..a320736 100644
--- a/src/vmath.nim
+++ b/src/vmath.nim
@@ -519,6 +519,31 @@ type
   DVec3* = GVec3[float64]
   DVec4* = GVec4[float64]
 
+when not defined(vmathArrayBased):
+  proc len*[T](a: GVec2[T]): int =
+    ## Returns the number of vector components, mirroring GLSL's .length() method.
+    2
+
+  proc len*[T](a: GVec3[T]): int =
+    ## Returns the number of vector components, mirroring GLSL's .length() method.
+    3
+
+  proc len*[T](a: GVec4[T]): int =
+    ## Returns the number of vector components, mirroring GLSL's .length() method.
+    4
+
+  proc len*[T](a: GMat2[T]): int =
+    ## Returns the number of matrix columns, mirroring GLSL's .length() method.
+    2
+
+  proc len*[T](a: GMat3[T]): int =
+    ## Returns the number of matrix columns, mirroring GLSL's .length() method.
+    3
+
+  proc len*[T](a: GMat4[T]): int =
+    ## Returns the number of matrix columns, mirroring GLSL's .length() method.
+    4
+
 proc `~=`*[T: SomeFloat](a, b: T): bool =
   ## Almost equal.
   const Epsilon = 0.000001
diff --git a/tests/tests.nim b/tests/tests.nim
index f0e7a52..b035cf2 100644
--- a/tests/tests.nim
+++ b/tests/tests.nim
@@ -28,6 +28,24 @@ suite "approximate equality":
   test "int ~= should not compile":
     check not compiles(1 ~= 1)
 
+suite "len":
+  test "vector component count":
+    check vec2(10.0, 2.0).len == 2
+    check len(vec3(1, 2, 3)) == 3
+    check vec4(0).len == 4
+    check dvec4(0).len == 4
+    check ivec3(0).len == 3
+    check uvec2(0).len == 2
+    check bvec4(false).len == 4
+
+  test "matrix column count":
+    check mat2().len == 2
+    check mat3().len == 3
+    check mat4().len == 4
+    check dmat2().len == 2
+    check dmat3().len == 3
+    check dmat4().len == 4
+
 suite "scalar utilities":
   test "between":
     check between(0.5, 0, 1)