<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

Hz: Represents a frequency in hertz. Examples:0Hz,1500Hz,10000Hz.
kHz: Represents a frequency in kilohertz. Examples:0kHz,1.5kHz,10kHz.

Note:Although the number0 is always the same regardless of unit, the unit may not be omitted. In other words,0 is invalid and does not represent0Hz or0kHz. Though the units are case-insensitive, it is good practice to use a capital "H" forHz andkHz, as specified in theSI.

Examples

Valid frequency values:

12Hz     Positive integer4.3Hz    Non-integer14KhZ    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>.