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 

<frequency>

The <frequency> CSS data type represents a frequency dimension, such as the pitch of a speaking voice. It is not currently used in any CSS properties.

Syntax

The <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.

Units

Represents a frequency in hertz. Examples: 0Hz, 1500Hz, 10000Hz.

Represents a frequency in kilohertz. Examples: 0kHz, 1.5kHz, 10kHz.

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 0Hz or 0kHz. Though the units are case-insensitive, it is good practice to use a capital "H" for Hz and kHz, as specified in the SI.

Examples

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 an allowable <length>, it's an invalid <frequency>. 

Specifications

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.

See also

Last modified: Nov 21, 2021, by MDN contributors