<frequency> data type consists of a
<number> followed by one of the units listed below. As with all CSS dimensions, there is no space between the unit literal and the number.
- Represents a frequency in hertz. Examples:
- Represents a frequency in kilohertz. Examples:
Note: Although the number
0 is always the same regardless of unit, the unit may not be omitted. In other words,
0 is invalid and does not represent
0kHz. Though the units are case-insensitive, it is good practice to use a capital "H" for
kHz, as specified in the SI.
Valid frequency values
12Hz Positive integer 4.3Hz Non-integer 14KhZ The unit is case-insensitive, though non-SI capitalization is not recommended. +0Hz Zero, with a leading + and a unit -0kHz Zero, with a leading - and a unit
Invalid frequency values
12.0 This is a <number>, not an <frequency>, because it is missing a unit. 7 Hz No space is allowed between the number and the unit. 0 Although unitless zero is allowed for <length>s, it's invalid for <frequency>s.
|CSS Values and Units Module Level 3
The definition of '<frequency>' in that specification.
|Candidate Recommendation||Initial definition.|
Note: This data type was initially introduced in CSS Level 2 for the now-obsolete aural media type, where it was used to define the pitch of the voice. However, the
<frequency> data type has been reintroduced in CSS3, though no CSS property is using it at the moment.