mod()

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

The mod() CSS function returns a modulus left over when the first parameter is divided by the second parameter, similar to the JavaScript remainder operator (%). The modulus is the value left over when one operand, the dividend, is divided by a second operand, the divisor. It always takes the sign of the divisor.

For example, the CSS mod(21, -4) function returns the remainder of -1. When dividing 21 by -4, the result is 5 with a remainder of -1. The full calculation is 21 / -4 = -4 * 5 - 1.

Syntax

css
/* Unitless <number> */
line-height: mod(7, 2); /* 1 */
line-height: mod(14, 5); /* 4 */
line-height: mod(3.5, 2); /* 1.5 */

/* Unit based <percentage> and <dimension> */
margin: mod(15%, 2%); /* 1% */
margin: mod(18px, 4px); /* 2px */
margin: mod(19rem, 5rem); /* 4rem */
margin: mod(29vmin, 6vmin); /* 5vmin */
margin: mod(1000px, 29rem); /* 72px - if root font-size is 16px */

/* Negative/positive values */
rotate: mod(100deg, 30deg); /* 10deg */
rotate: mod(135deg, -90deg); /* -45deg */
rotate: mod(-70deg, 20deg); /* 10deg */
rotate: mod(-70deg, -15deg); /* -10deg */

/* Calculations */
scale: mod(10 * 2, 1.7); /* 1.3 */
rotate: mod(10turn, 18turn / 3); /* 4turn */
transition-duration: mod(20s / 2, 3000ms * 2); /* 4s */

Parameter

The mod(dividend, divisor) function accepts two comma-separated values as its parameters. Both parameters must have the same type, number, dimension, or <percentage>, for the function to be valid. While the units in the two parameters don't need to be the same, they do need of the same dimension type, such as <length>, <angle>, <time>, or <frequency> to be valid.

dividend

A calculation that resolves to a <number>, <dimension>, or <percentage> representing the dividend.

divisor

A calculation that resolves to a <number>, <dimension>, or <percentage> representing the divisor.

Return value

Returns a <number>, <dimension>, or <percentage> (corresponds to the parameters' type) representing the modulus, that is, the operation left over.

  • If divisor is 0, the result is NaN.
  • If dividend is infinite, the result is NaN.
  • If divisor is positive the result is positive (0⁺), and if divisor is negative the result is negative (0⁻).

Formal syntax

<mod()> = 
  mod( <calc-sum> , <calc-sum> )  

<calc-sum> = 
  <calc-product> [ [ '+' | '-' ] <calc-product> ]*  

<calc-product> = 
  <calc-value> [ [ '*' | '/' ] <calc-value> ]*  

<calc-value> = 
  <number>        |
  <dimension>     |
  <percentage>    |
  <calc-keyword>  |
  ( <calc-sum> )  

<calc-keyword> = 
  e          |
  pi         |
  infinity   |
  -infinity  |
  NaN

Specifications

Specification
CSS Values and Units Module Level 4
# funcdef-mod

Browser compatibility

Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
mod()

See also