diff --git a/test/date_test/sizeof.pass.cpp b/test/date_test/sizeof.pass.cpp
new file mode 100644
index 0000000..104507c
--- /dev/null
+++ b/test/date_test/sizeof.pass.cpp
@@ -0,0 +1,62 @@
+// The MIT License (MIT)
+// 
+// Copyright (c) 2015 Howard Hinnant
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+// This test is meant to maintain a record of the sizeof each type.
+
+#include "date.h"
+
+int
+main()
+{
+    using namespace date;
+
+    static_assert(sizeof(days)                    == 4, "");
+    static_assert(sizeof(weeks)                   == 4, "");
+    static_assert(sizeof(months)                  == 4, "");
+    static_assert(sizeof(years)                   == 4, "");
+
+    static_assert(sizeof(day_point)               == 4, "");
+
+    static_assert(sizeof(last_spec)               == 1, "");
+
+    static_assert(sizeof(day)                     == 1, "");
+    static_assert(sizeof(month)                   == 1, "");
+    static_assert(sizeof(year)                    == 2, "");
+
+    static_assert(sizeof(weekday)                 == 1, "");
+    static_assert(sizeof(weekday_indexed)         == 1, "");
+    static_assert(sizeof(weekday_last)            == 1, "");
+
+    static_assert(sizeof(month_day)               == 2, "");
+    static_assert(sizeof(month_day_last)          == 1, "");
+    static_assert(sizeof(month_weekday)           == 2, "");
+    static_assert(sizeof(month_weekday_last)      == 2, "");
+
+    static_assert(sizeof(year_month)              == 4, "");
+
+    static_assert(sizeof(year_month_day)          == 4, "");
+    static_assert(sizeof(year_month_day_last)     == 4, "");
+    static_assert(sizeof(year_month_weekday)      == 4, "");
+    static_assert(sizeof(year_month_weekday_last) == 4, "");
+
+    // sizeof time_of_day varies
+}