--- layout: docs title: Grid system description: Use our powerful mobile-first flexbox grid to build layouts of all shapes and sizes thanks to a twelve column system, five default responsive tiers, Sass variables and mixins, and dozens of predefined classes. group: layout toc: true --- ## How it works Bootstrap's grid system uses a series of containers, rows, and columns to layout and align content. It's built with [flexbox](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Flexible_Box_Layout/Using_CSS_flexible_boxes) and is fully responsive. Below is an example and an in-depth look at how the grid comes together. **New to or unfamiliar with flexbox?** [Read this CSS Tricks flexbox guide](https://css-tricks.com/snippets/css/a-guide-to-flexbox/#flexbox-background) for background, terminology, guidelines, and code snippets.

{% example html %}

One of three columns

{% endexample %}

The above example creates three equal-width columns on small, medium, large, and extra large devices using our predefined grid classes. Those columns are centered in the page with the parent `.container`. Breaking it down, here's how it works: - Containers provide a means to center and horizontally pad your site's contents. Use `.container` for a responsive pixel width or `.container-fluid` for `width: 100%` across all viewport and device sizes. - Rows are wrappers for columns. Each column has horizontal `padding` (called a gutter) for controlling the space between them. This `padding` is then counteracted on the rows with negative margins. This way, all the content in your columns is visually aligned down the left side. - In a grid layout, content must be placed within columns and only columns may be immediate children of rows. - Thanks to flexbox, grid columns without a specified `width` will automatically layout as equal width columns. For example, four instances of `.col-sm` will each automatically be 25% wide from the small breakpoint and up. See the [auto-layout columns](#auto-layout-columns) section for more examples. - Column classes indicate the number of columns you'd like to use out of the possible 12 per row. So, if you want three equal-width columns across, you can use `.col-4`. - Column `width`s are set in percentages, so they're always fluid and sized relative to their parent element. - Columns have horizontal `padding` to create the gutters between individual columns, however, you can remove the `margin` from rows and `padding` from columns with `.no-gutters` on the `.row`. - To make the grid responsive, there are five grid breakpoints, one for each [responsive breakpoint]({{ site.baseurl }}/docs/{{ site.docs_version }}/layout/overview/#responsive-breakpoints): all breakpoints (extra small), small, medium, large, and extra large. - Grid breakpoints are based on minimum width media queries, meaning **they apply to that one breakpoint and all those above it** (e.g., `.col-sm-4` applies to small, medium, large, and extra large devices, but not the first `xs` breakpoint). - You can use predefined grid classes (like `.col-4`) or [Sass mixins](#sass-mixins) for more semantic markup. Be aware of the limitations and [bugs around flexbox](https://github.com/philipwalton/flexbugs), like the [inability to use some HTML elements as flex containers](https://github.com/philipwalton/flexbugs#9-some-html-elements-cant-be-flex-containers). ## Grid options While Bootstrap uses `em`s or `rem`s for defining most sizes, `px`s are used for grid breakpoints and container widths. This is because the viewport width is in pixels and does not change with the [font size](https://drafts.csswg.org/mediaqueries-3/#units). See how aspects of the Bootstrap grid system work across multiple devices with a handy table.

	Extra small <576px	Small ≥576px	Medium ≥768px	Large ≥992px	Extra large ≥1200px
Max container width	None (auto)	540px	720px	960px	1140px
Class prefix	`.col-`	`.col-sm-`	`.col-md-`	`.col-lg-`	`.col-xl-`
# of columns	12
Gutter width	30px (15px on each side of a column)
Nestable	Yes
Column ordering	Yes

## Auto-layout columns Utilize breakpoint-specific column classes for easy column sizing without an explicit numbered class like `.col-sm-6`. ### Equal-width For example, here are two grid layouts that apply to every device and viewport, from `xs` to `xl`. Add any number of unit-less classes for each breakpoint you need and every column will be the same width.

{% example html %}

1 of 2

2 of 2

1 of 3

2 of 3

3 of 3

{% endexample %}

Equal-width columns can be broken into multiple lines, but there was a [Safari flexbox bug](https://github.com/philipwalton/flexbugs#11-min-and-max-size-declarations-are-ignored-when-wrapping-flex-items) that prevented this from working without an explicit `flex-basis` or `border`. There are workarounds for older browser versions, but they shouldn't be necessary if you're up-to-date.

{% example html %}

Column

{% endexample %}

### Setting one column width Auto-layout for flexbox grid columns also means you can set the width of one column and have the sibling columns automatically resize around it. You may use predefined grid classes (as shown below), grid mixins, or inline widths. Note that the other columns will resize no matter the width of the center column.

{% example html %}

1 of 3

2 of 3 (wider)

3 of 3

1 of 3

2 of 3 (wider)

3 of 3

{% endexample %}

### Variable width content Use `col-{breakpoint}-auto` classes to size columns based on the natural width of their content.

{% example html %}

1 of 3

Variable width content

3 of 3

1 of 3

Variable width content

3 of 3

{% endexample %}

### Equal-width multi-row Create equal-width columns that span multiple rows by inserting a `.w-100` where you want the columns to break to a new line. Make the breaks responsive by mixing the `.w-100` with some [responsive display utilities]({{ site.baseurl }}/docs/{{ site.docs_version }}/utilities/display/).

{% example html %}

col

{% endexample %}

## Responsive classes Bootstrap's grid includes five tiers of predefined classes for building complex responsive layouts. Customize the size of your columns on extra small, small, medium, large, or extra large devices however you see fit. ### All breakpoints For grids that are the same from the smallest of devices to the largest, use the `.col` and `.col-*` classes. Specify a numbered class when you need a particularly sized column; otherwise, feel free to stick to `.col`.

{% example html %}

col

col-8

col-4

{% endexample %}

### Stacked to horizontal Using a single set of `.col-sm-*` classes, you can create a basic grid system that starts out stacked before becoming horizontal with at the small breakpoint (`sm`).

{% example html %}

col-sm-8

col-sm-4

col-sm

{% endexample %}

### Mix and match Don't want your columns to simply stack in some grid tiers? Use a combination of different classes for each tier as needed. See the example below for a better idea of how it all works.

{% example html %}

.col-12 .col-md-8

.col-6 .col-md-4

.col-6

{% endexample %}

## Alignment Use flexbox alignment utilities to vertically and horizontally align columns. ### Vertical alignment

{% example html %}

One of three columns

{% endexample %}

{% example html %}

One of three columns

{% endexample %}

### Horizontal alignment

{% example html %}

One of two columns

{% endexample %}

### No gutters The gutters between columns in our predefined grid classes can be removed with `.no-gutters`. This removes the negative `margin`s from `.row` and the horizontal `padding` from all immediate children columns. Here's the source code for creating these styles. Note that column overrides are scoped to only the first children columns and are targeted via [attribute selector](https://developer.mozilla.org/en-US/docs/Web/CSS/Attribute_selectors). While this generates a more specific selector, column padding can still be further customized with [spacing utilities]({{ site.baseurl }}/docs/{{ site.docs_version }}/utilities/spacing/). **Need an edge-to-edge design?** Drop the parent `.container` or `.container-fluid`. {% highlight sass %} .no-gutters { margin-right: 0; margin-left: 0; > .col, > [class*="col-"] { padding-right: 0; padding-left: 0; } } {% endhighlight %} In practice, here's how it looks. Note you can continue to use this with all other predefined grid classes (including column widths, responsive tiers, reorders, and more).

{% example html %}

.col-12 .col-sm-6 .col-md-8

.col-6 .col-md-4

{% endexample %}

### Column wrapping If more than 12 columns are placed within a single row, each group of extra columns will, as one unit, wrap onto a new line.

{% example html %}

.col-9

.col-4
Since 9 + 4 = 13 > 12, this 4-column-wide div gets wrapped onto a new line as one contiguous unit.

.col-6
Subsequent columns continue along the new line.

{% endexample %}

### Column breaks Breaking columns to a new line in flexbox requires a small hack: add an element with `width: 100%` wherever you want to wrap your columns to a new line. Normally this is accomplished with multiple `.row`s, but not every implementation method can account for this.

{% example html %}

.col-6 .col-sm-3

{% endexample %}

You may also apply this break at specific breakpoints with our [responsive display utilities]({{ site.baseurl }}/docs/{{ site.docs_version }}/utilities/display/).

{% example html %}

.col-6 .col-sm-4

{% endexample %}

## Reordering ### Order classes Use `.order-` classes for controlling the **visual order** of your content. These classes are responsive, so you can set the `order` by breakpoint (e.g., `.order-1.order-md-2`). Includes support for `1` through `12` across all five grid tiers.

{% example html %}

First, but unordered

Second, but last

Third, but first

{% endexample %}

There are also responsive `.order-first` and `.order-last` classes that change the `order` of an element by applying `order: -1` and `order: 13` (`order: $columns + 1`), respectively. These classes can also be intermixed with the numbered `.order-*` classes as needed.

{% example html %}

First, but last

Second, but unordered

Third, but first

{% endexample %}

### Offsetting columns You can offset grid columns in two ways: our responsive `.offset-` grid classes and our [margin utilities]({{ site.baseurl }}/docs/{{ site.docs_version }}/utilities/spacing/). Grid classes are sized to match columns while margins are more useful for quick layouts where the width of the offset is variable. #### Offset classes Move columns to the right using `.offset-md-*` classes. These classes increase the left margin of a column by `*` columns. For example, `.offset-md-4` moves `.col-md-4` over four columns.

{% example html %}

.col-md-4

.col-md-4 .offset-md-4

.col-md-3 .offset-md-3

.col-md-6 .offset-md-3

{% endexample %}

In addition to column clearing at responsive breakpoints, you may need to reset offsets. See this in action in [the grid example]({{ site.baseurl }}/docs/{{ site.docs_version }}/examples/grid/).

{% example html %}

.col-sm-5 .col-md-6

.col-sm-5 .offset-sm-2 .col-md-6 .offset-md-0

.col-sm-6 .col-md-5 .col-lg-6

.col-sm-6 .col-md-5 .offset-md-2 .col-lg-6 .offset-lg-0

{% endexample %}

#### Margin utilities With the move to flexbox in v4, you can use margin utilities like `.mr-auto` to force sibling columns away from one another.

{% example html %}

.col-md-4

.col-md-4 .ml-auto

.col-md-3 .ml-md-auto

.col-auto .mr-auto

.col-auto

{% endexample %}

## Nesting To nest your content with the default grid, add a new `.row` and set of `.col-sm-*` columns within an existing `.col-sm-*` column. Nested rows should include a set of columns that add up to 12 or fewer (it is not required that you use all 12 available columns).

{% example html %}

Level 1: .col-sm-9

Level 2: .col-8 .col-sm-6

Level 2: .col-4 .col-sm-6

{% endexample %}

## Sass mixins When using Bootstrap's source Sass files, you have the option of using Sass variables and mixins to create custom, semantic, and responsive page layouts. Our predefined grid classes use these same variables and mixins to provide a whole suite of ready-to-use classes for fast responsive layouts. ### Variables Variables and maps determine the number of columns, the gutter width, and the media query point at which to begin floating columns. We use these to generate the predefined grid classes documented above, as well as for the custom mixins listed below. {% highlight scss %} $grid-columns: 12; $grid-gutter-width: 30px; $grid-breakpoints: ( // Extra small screen / phone xs: 0, // Small screen / phone sm: 576px, // Medium screen / tablet md: 768px, // Large screen / desktop lg: 992px, // Extra large screen / wide desktop xl: 1200px ); $container-max-widths: ( sm: 540px, md: 720px, lg: 960px, xl: 1140px ); {% endhighlight %} ### Mixins Mixins are used in conjunction with the grid variables to generate semantic CSS for individual grid columns. {% highlight scss %} // Creates a wrapper for a series of columns @include make-row(); // Make the element grid-ready (applying everything but the width) @include make-col-ready(); @include make-col($size, $columns: $grid-columns); // Get fancy by offsetting, or changing the sort order @include make-col-offset($size, $columns: $grid-columns); {% endhighlight %} ### Example usage You can modify the variables to your own custom values, or just use the mixins with their default values. Here's an example of using the default settings to create a two-column layout with a gap between. {% highlight scss %} .example-container { width: 800px; @include make-container(); } .example-row { @include make-row(); } .example-content-main { @include make-col-ready(); @include media-breakpoint-up(sm) { @include make-col(6); } @include media-breakpoint-up(lg) { @include make-col(8); } } .example-content-secondary { @include make-col-ready(); @include media-breakpoint-up(sm) { @include make-col(6); } @include media-breakpoint-up(lg) { @include make-col(4); } } {% endhighlight %} {% example html %}

Main content

Secondary content

{% endexample %} ## Customizing the grid Using our built-in grid Sass variables and maps, it's possible to completely customize the predefined grid classes. Change the number of tiers, the media query dimensions, and the container widths—then recompile. ### Columns and gutters The number of grid columns can be modified via Sass variables. `$grid-columns` is used to generate the widths (in percent) of each individual column while `$grid-gutter-width` allows breakpoint-specific widths that are divided evenly across `padding-left` and `padding-right` for the column gutters. {% highlight scss %} $grid-columns: 12 !default; $grid-gutter-width: 30px !default; {% endhighlight %} ### Grid tiers Moving beyond the columns themselves, you may also customize the number of grid tiers. If you wanted just four grid tiers, you'd update the `$grid-breakpoints` and `$container-max-widths` to something like this: {% highlight scss %} $grid-breakpoints: ( xs: 0, sm: 480px, md: 768px, lg: 1024px ); $container-max-widths: ( sm: 420px, md: 720px, lg: 960px ); {% endhighlight %} When making any changes to the Sass variables or maps, you'll need to save your changes and recompile. Doing so will output a brand new set of predefined grid classes for column widths, offsets, and ordering. Responsive visibility utilities will also be updated to use the custom breakpoints. Make sure to set grid values in `px` (not `rem`, `em`, or `%`).