The grid-auto-columns CSS property specifies the size of an implicitly-created grid column track.

/* Keyword values */
grid-auto-columns: min-content;
grid-auto-columns: max-content;
grid-auto-columns: auto;

/* <length> values */
grid-auto-columns: 100px;
grid-auto-columns: 20cm;
grid-auto-columns: 50vmax;

/* <percentage> values */
grid-auto-columns: 10%;
grid-auto-columns: 33.3%;

/* <flex> values */
grid-auto-columns: 0.5fr;
grid-auto-columns: 3fr;

/* minmax() values */
grid-auto-columns: minmax(100px, auto);
grid-auto-columns: minmax(max-content, 2fr);
grid-auto-columns: minmax(20%, 80vmax);

/* fit-content() values */
grid-auto-columns: fit-content(400px);
grid-auto-columns: fit-content(5cm);
grid-auto-columns: fit-content(20%);

/* multiple track-size values */
grid-auto-columns: min-content max-content auto;
grid-auto-columns: 100px 150px 390px;
grid-auto-columns: 10% 33.3%;
grid-auto-columns: 0.5fr 3fr 1fr;
grid-auto-columns: minmax(100px, auto) minmax(max-content, 2fr) minmax(20%, 80vmax);
grid-auto-columns: 100px minmax(100px, auto) 10% 0.5fr fit-content(400px);

/* Global values */
grid-auto-columns: inherit;
grid-auto-columns: initial;
grid-auto-columns: unset;

If a grid item is positioned into a column that is not explicitly sized by grid-template-columns, implicit grid tracks are created to hold it. This can happen either by explicitly positioning into a column that is out of range, or by the auto-placement algorithm creating additional columns.

Initial value auto
Applies to grid containers
Inherited no
Percentages refer to corresponding dimension of the content area
Media visual
Computed value the percentage as specified or the absolute length
Animation type discrete
Canonical order the unique non-ambiguous order defined by the formal grammar



Is a non-negative length.
Is a non-negative <percentage> value relative to the block size of the grid container. If the block size of the grid container is indefinite, the percentage value is treated like auto.
Is a non-negative dimension with the unit fr specifying the track’s flex factor. Each <flex>-sized track takes a share of the remaining space in proportion to its flex factor.

When appearing outside a minmax() notation, it implies an automatic minimum (i.e. minmax(auto, <flex>)).

Is a keyword representing the largest maximal content contribution of the grid items occupying the grid track.
Is a keyword representing the largest minimal content contribution of the grid items occupying the grid track.
minmax(min, max)
Is a functional notation that defines a size range greater than or equal to min and less than or equal to max. If max is smaller than min, then max is ignored and the function is treated as min. As a maximum, a <flex> value sets the track’s flex factor. As a minimum, it is treated as zero (or minimal content, if the grid container is sized under a minimal content constraint).
fit-content(min, max)
Represents the formula min(max-content, max(auto, argument)), which is calculated similar to auto (i.e. minmax(auto, max-content)), except that the track size is clamped at argument if it is greater than the auto minimum.
Is a keyword that is identical to maximal content if it's a maximum. As a minimum it represents the largest minimum size (as specified by min-width/min-height) of the grid items occupying the grid track.

Note: auto track sizes (and only auto track sizes) can be streched by the align-content and justify-content properties.

Formal syntax


<track-size> = <track-breadth> | minmax( <inflexible-breadth> , <track-breadth> ) | fit-content( [ <length> | <percentage> ] )

<track-breadth> = <length-percentage> | <flex> | min-content | max-content | auto
<inflexible-breadth> = <length> | <percentage> | min-content | max-content | auto

<length-percentage> = <length> | <percentage>


HTML content

<div id="grid">
  <div id="item1"></div>
  <div id="item2"></div>
  <div id="item3"></div>

CSS content

#grid {
  height: 100px;
  display: grid;
  grid-template-areas: "a a";
  grid-gap: 10px;
  grid-auto-columns: 200px;

#grid > div {
  background-color: lime;


Specification Status Comment
CSS Grid Layout
The definition of 'grid-auto-columns' in that specification.
Candidate Recommendation Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Edge Opera Safari
Basic support 57.0[1] 52.0 (52.0)[2] 10.0-ms[3] 20-ms[3] 44[4] 10.1
Feature Android Webview Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support 57.0[1] 57.0[1] 52.0 (52.0)[2] 10.0-ms[3] 44 No support

[1] Implemented behind the experimental Web Platform features flag in chrome://flags since Chrome 29.0.

[2] Implemented behind the preference layout.css.grid.enabled since Gecko 40.0 (Firefox 40.0 / Thunderbird 40.0 / SeaMonkey 2.37), defaulting to false. Since Gecko 52.0 (Firefox 52.0 / Thunderbird 52.0 / SeaMonkey 2.49) it is enabled by default.

[3] Internet Explorer implements an older version of the specification using the -ms prefix. Therefore the property is implemented there as -ms-grid-columns.

[4] Implemented behind the Enable experimental Web Platform features flag in chrome://flags since Opera 28.0.

See also

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