diff --git a/headers/enum.hpp/enum.hpp b/headers/enum.hpp/enum.hpp
index d4a6013..5955176 100644
--- a/headers/enum.hpp/enum.hpp
+++ b/headers/enum.hpp/enum.hpp
@@ -16,6 +16,8 @@ namespace enum_hpp
         explicit exception(const char* what)
         : std::runtime_error(what) {}
     };
+
+    constexpr std::size_t invalid_index = std::size_t(-1);
 }
 
 namespace enum_hpp::detail
@@ -146,6 +148,30 @@ namespace enum_hpp::detail
             }\
             return false;\
         }\
+        \
+        static constexpr std::size_t to_index(Enum e) noexcept {\
+            for ( std::size_t i = 0; i < size; ++i ) {\
+                if ( e == values[i] ) {\
+                    return i;\
+                }\
+            }\
+            return ::enum_hpp::invalid_index;\
+        }\
+        \
+        static Enum from_index(std::size_t index) {\
+            if ( index < size ) {\
+                return values[index];\
+            }\
+            throw ::enum_hpp::exception(#Enum "_traits::from_index(): invalid argument");\
+        }\
+        \
+        static constexpr bool from_index_nothrow(std::size_t index, Enum& result) noexcept {\
+            if ( index < size ) {\
+                result = values[index];\
+                return true;\
+            }\
+            return false;\
+        }\
     };
 
 // -----------------------------------------------------------------------------
diff --git a/untests/enum_tests.cpp b/untests/enum_tests.cpp
index 64aea69..109f2f3 100644
--- a/untests/enum_tests.cpp
+++ b/untests/enum_tests.cpp
@@ -182,4 +182,80 @@ TEST_CASE("enum") {
             REQUIRE(result == sn::_240);
         }
     }
+
+    SECTION("to_index") {
+        {
+            STATIC_REQUIRE(sn::color_traits::to_index(sn::color::red) == 0);
+            STATIC_REQUIRE(sn::color_traits::to_index(sn::color::green) == 1);
+            STATIC_REQUIRE(sn::color_traits::to_index(sn::color::blue) == 2);
+            STATIC_REQUIRE(sn::color_traits::to_index(sn::color(42)) == enum_hpp::invalid_index);
+        }
+        {
+            STATIC_REQUIRE(sn::render::mask_traits::to_index(sn::render::mask::none) == 0);
+            STATIC_REQUIRE(sn::render::mask_traits::to_index(sn::render::mask::color) == 1);
+            STATIC_REQUIRE(sn::render::mask_traits::to_index(sn::render::mask::alpha) == 2);
+            STATIC_REQUIRE(sn::render::mask_traits::to_index(sn::render::mask::all) == 3);
+        }
+        {
+            STATIC_REQUIRE(sn::numbers_traits::to_index(sn::_0) == 0);
+            STATIC_REQUIRE(sn::numbers_traits::to_index(sn::_180) == 180);
+            STATIC_REQUIRE(sn::numbers_traits::to_index(sn::_240) == 240);
+            STATIC_REQUIRE(sn::numbers_traits::to_index(sn::numbers(100500)) == enum_hpp::invalid_index);
+        }
+    }
+
+    SECTION("from_index") {
+        {
+            REQUIRE(sn::color_traits::from_index(0) == sn::color::red);
+            REQUIRE(sn::color_traits::from_index(1) == sn::color::green);
+            REQUIRE(sn::color_traits::from_index(2) == sn::color::blue);
+            REQUIRE_THROWS_AS(sn::color_traits::from_index(42), enum_hpp::exception);
+        }
+        {
+            REQUIRE(sn::render::mask_traits::from_index(0) == sn::render::mask::none);
+            REQUIRE(sn::render::mask_traits::from_index(1) == sn::render::mask::color);
+            REQUIRE(sn::render::mask_traits::from_index(2) == sn::render::mask::alpha);
+            REQUIRE(sn::render::mask_traits::from_index(3) == sn::render::mask::all);
+            REQUIRE_THROWS_AS(sn::render::mask_traits::from_index(42), enum_hpp::exception);
+        }
+        {
+            REQUIRE(sn::numbers_traits::from_index(10) == sn::_10);
+            REQUIRE(sn::numbers_traits::from_index(240) == sn::_240);
+            REQUIRE_THROWS_AS(sn::numbers_traits::from_index(100500), enum_hpp::exception);
+        }
+    }
+
+    SECTION("from_index_nothrow") {
+        {
+            sn::color result{42};
+            REQUIRE(sn::color_traits::from_index_nothrow(0, result));
+            REQUIRE(result == sn::color::red);
+            REQUIRE(sn::color_traits::from_index_nothrow(1, result));
+            REQUIRE(result == sn::color::green);
+            REQUIRE(sn::color_traits::from_index_nothrow(2, result));
+            REQUIRE(result == sn::color::blue);
+            REQUIRE_FALSE(sn::color_traits::from_index_nothrow(42, result));
+            REQUIRE(result == sn::color::blue);
+        }
+        {
+            sn::render::mask result{42};
+            REQUIRE(sn::render::mask_traits::from_index_nothrow(0, result));
+            REQUIRE(result == sn::render::mask::none);
+            REQUIRE(sn::render::mask_traits::from_index_nothrow(1, result));
+            REQUIRE(result == sn::render::mask::color);
+            REQUIRE(sn::render::mask_traits::from_index_nothrow(2, result));
+            REQUIRE(result == sn::render::mask::alpha);
+            REQUIRE(sn::render::mask_traits::from_index_nothrow(3, result));
+            REQUIRE(result == sn::render::mask::all);
+            REQUIRE_FALSE(sn::render::mask_traits::from_index_nothrow(42, result));
+            REQUIRE(result == sn::render::mask::all);
+        }
+        {
+            sn::numbers result{100500};
+            REQUIRE(sn::numbers_traits::from_index_nothrow(240, result));
+            REQUIRE(result == sn::_240);
+            REQUIRE_FALSE(sn::numbers_traits::from_index_nothrow(100500, result));
+            REQUIRE(result == sn::_240);
+        }
+    }
 }