The <number> CSS data type represents a number, either integer or fractional. Its syntax extends the one of the <integer> data value. To represent a fractional value, add the fractional part — a '.' followed by one or several decimal digits — to any <integer> data value. Like for <integer> data type, there isn't any unit associated to a <number>, which is not a CSS dimension.


Values of the <number> CSS data type can be interpolated in order to allow animations. In that case they are interpolated as real, floating-point, numbers. The speed of the interpolation is determined by the timing function associated with the animation.


These are valid number values:

12          A raw <integer> is also a <number>
4.01        A positive non-integer <number>
-456.8      Negative non-integer <number>
0.0         Zero
+0.0        Zero, with a leading +
-0.0        Zero, with a leading - (Though strange, this is an allowed value)
.60         Digits are optional before the dot
10e3        The scientific notation is allowed
-3.4e-2     Most complex case of scientific notation

These are invalid number values:

12.         The dot should be followed by a number
+-12.2      Only one leading +/- is allowed
12.1.1      Only one dot is allowed


Specification Status Comment
CSS Values and Units Module Level 3
The definition of '<number>' in that specification.
Candidate Recommendation No significant change from CSS Level 2 (Revision 1)
CSS Level 2 (Revision 1)
The definition of '<number>' in that specification.
Recommendation Explicitly defined
CSS Level 1
The definition of '<number>' in that specification.
Recommendation Implicitly defined

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 1.0 1.0 (1.0) 5.0 (Yes) 1.0 (85)
Scientific notation 43.0 29 11 ? ?
Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Scientific notation (Yes) (Yes) (Yes) (Yes) (Yes)

Document Tags and Contributors

 Last updated by: fscholz,