diff --git a/doc/man/task.1.in b/doc/man/task.1.in
index b3608b744..bc1dc1a37 100644
--- a/doc/man/task.1.in
+++ b/doc/man/task.1.in
@@ -379,6 +379,22 @@ time from the specified task.
 Miscellaneous subcommands either accept no command line arguments, or accept
 non-standard arguments.
 
+.TP
+.B task calc <expression>
+Evaluates an algebraic expression. Can be used to test how TaskWarrior
+parses and evaluates the expression given on the command line.
+
+Examples:
+
+    task calc 1 + 1
+    2
+
+    task calc now + 8d
+    2015-03-26T18:06:57
+
+    task calc eom
+    2015-03-31T23:59:59
+
 .TP
 .B task config [name [value | '']]
 Add, modify and remove settings directly in the taskwarrior configuration.