diff --git a/extent.cpp b/extent.cpp
index a6bb2a47..df08e0eb 100644
--- a/extent.cpp
+++ b/extent.cpp
@@ -42,34 +42,6 @@ extent<S,T>::extent (vector<S,T> _v)
 }
 
 
-///////////////////////////////////////////////////////////////////////////////
-template <size_t S, typename T>
-T
-extent<S,T>::diameter (void) const
-{
-    return static_cast<T> (
-        std::sqrt (
-            std::accumulate (std::begin (this->data),
-                             std::end   (this->data),
-                             T {0},
-                             [] (auto a, auto b) { return a + b * b; })
-        )
-    );
-}
-
-
-//-----------------------------------------------------------------------------
-template <size_t S, typename T>
-T
-extent<S,T>::area (void) const
-{
-    return std::accumulate (std::begin (this->data),
-                            std::end   (this->data),
-                            T {1},
-                            std::multiplies<T> ());
-}
-
-
 ///////////////////////////////////////////////////////////////////////////////
 template <size_t S, typename T>
 extent<S,T>
diff --git a/extent.hpp b/extent.hpp
index ae220166..f700b04f 100644
--- a/extent.hpp
+++ b/extent.hpp
@@ -34,10 +34,11 @@ namespace util {
         extent () = default;
         explicit extent (vector<S,T>);
 
-        T    area  (void) const;
-        T diameter (void) const;
+        constexpr T    area  (void) const;
+        constexpr T diameter (void) const;
 
         template <typename U = float>
+        constexpr
         U aspect (void) const;
 
         template <typename U>
diff --git a/extent.ipp b/extent.ipp
index 3e8cd83b..8c4ddecf 100644
--- a/extent.ipp
+++ b/extent.ipp
@@ -24,9 +24,40 @@
 #include <algorithm>
 
 
+///////////////////////////////////////////////////////////////////////////////
+template <size_t S, typename T>
+constexpr
+T
+util::extent<S,T>::diameter (void) const
+{
+    return static_cast<T> (
+        std::sqrt (
+            std::accumulate (std::begin (this->data),
+                             std::end   (this->data),
+                             T {0},
+                             [] (auto a, auto b) { return a + b * b; })
+        )
+    );
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+template <size_t S, typename T>
+constexpr
+T
+util::extent<S,T>::area (void) const
+{
+    return std::accumulate (std::begin (this->data),
+                            std::end   (this->data),
+                            T {1},
+                            std::multiplies<T> ());
+}
+
+
 ///////////////////////////////////////////////////////////////////////////////
 template <size_t S, typename T>
 template <typename U>
+constexpr
 U
 util::extent<S,T>::aspect (void) const
 {