diff --git a/doc/source/user_guide/data_types.txt b/doc/source/user_guide/data_types.txt
index 76d04862..9801c244 100644
--- a/doc/source/user_guide/data_types.txt
+++ b/doc/source/user_guide/data_types.txt
@@ -14,13 +14,13 @@ Data type  Range
 uint8      0 to 255
 uint16     0 to 65535
 uint32     0 to 2\ :sup:`32`
-float      0 to 1
+float      -1 to 1
 int8       -128 to 127
 int16      -32768 to 32767
 int32      -2\ :sup:`31` to 2\ :sup:`31` - 1
 =========  =================================
 
-Note that float images are restricted to the range 0 to 1 even though the data
+Note that float images are restricted to the range -1 to 1 even though the data
 type itself can exceed this range; all integer dtypes, on the other hand, have
 pixel intensities that can span the entire data type range. Currently, *64-bit
 (u)int images are not supported*.