<commit_before>---
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, six default responsive tiers, Sass variables and mixins, and dozens of predefined classes.
group: layout
toc: true
---

## Example

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/Basic_Concepts_of_Flexbox) and is fully responsive. Below is an example and an in-depth explanation for how the grid system comes together.

{{< callout info >}}
**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.
{{< /callout >}}

{{< example class="bd-example-row" >}}
<div class="container">
  <div class="row">
    <div class="col-sm">
      One of three columns
    </div>
    <div class="col-sm">
      One of three columns
    </div>
    <div class="col-sm">
      One of three columns
    </div>
  </div>
</div>
{{< /example >}}

The above example creates three equal-width columns across all devices and viewports using our predefined grid classes. Those columns are centered in the page with the parent `.container`.

## How it works

Breaking it down, here's how the grid system comes together:

- **Our grid supports [six responsive breakpoints]({{< docsref "/layout/breakpoints" >}}).**  Breakpoints are based on `min-width` media queries, meaning they affect that breakpoint and all those above it (e.g., `.col-sm-4` applies to `sm`, `md`, `lg`, `xl`, and `xxl`). This means you can control container and column sizing and behavior by each breakpoint.

- **Containers center and horizontally pad your content.** Use `.container` for a responsive pixel width, `.container-fluid` for `width: 100%` across all viewports and devices, or a responsive container (e.g., `.container-md`) fir combination of fluid and pixel widths.

- **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 to ensure the content in your columns is visually aligned down the left side. Rows also support modifier classes to [uniformly apply column sizing](#row-columns) and [gutter classes]({{< docsref "/layout/gutters" >}}) to change the spacing of your content.

- **Columns are incredibly flexible.** There are 12 template columns available per row, allowing you to create different combinations of elements that span any number of columns. Column classes indicate the number of template columns to span (e.g., `col-4` spans four). `width`s are set in percentages so you always have the same relative sizing.

- **Gutters are also responsive and customizable.** [Gutter classes are available]({{< docsref "/layout/gutters" >}}) across all breakpoints, with all the same sizes as our [margin and padding spacing]({{< docsref "/utilities/spacing" >}}). Change horizontal gutters with `.gx-*` classes, vertical gutters with `.gy-*`, or all gutters with `.g-*` classes. `.g-0` is also available to remove gutters.

- **Sass variables, maps, and mixins power the grid.** If you don't want to use the predefined grid classes in Bootstrap, you can use our [grid's source Sass](#sass) to create your own with more semantic markup. We also include some CSS custom properties to consume these Sass variables for even greater flexibility for you.

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#flexbug-9).

## Grid options

Bootstrap's grid system can adapt across all six default breakpoints, and any breakpoints you customize. The six default grid tiers are as follow:

- Extra small (xs)
- Small (sm)
- Medium (md)
- Large (lg)
- Extra large (xl)
- Extra extra large (xxl)

As noted above, each of these breakpoints have their own container, unique class prefix, and modifiers. Here's how the grid changes across these breakpoints:

<table class="table mb-4">
  <thead>
    <tr>
      <th scope="col"></th>
      <th scope="col">
        xs<br><commit_msg>Fix typo (#31102)<commit_after>---
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, six default responsive tiers, Sass variables and mixins, and dozens of predefined classes.
group: layout
toc: true
---

## Example

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/Basic_Concepts_of_Flexbox) and is fully responsive. Below is an example and an in-depth explanation for how the grid system comes together.

{{< callout info >}}
**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.
{{< /callout >}}

{{< example class="bd-example-row" >}}
<div class="container">
  <div class="row">
    <div class="col-sm">
      One of three columns
    </div>
    <div class="col-sm">
      One of three columns
    </div>
    <div class="col-sm">
      One of three columns
    </div>
  </div>
</div>
{{< /example >}}

The above example creates three equal-width columns across all devices and viewports using our predefined grid classes. Those columns are centered in the page with the parent `.container`.

## How it works

Breaking it down, here's how the grid system comes together:

- **Our grid supports [six responsive breakpoints]({{< docsref "/layout/breakpoints" >}}).**  Breakpoints are based on `min-width` media queries, meaning they affect that breakpoint and all those above it (e.g., `.col-sm-4` applies to `sm`, `md`, `lg`, `xl`, and `xxl`). This means you can control container and column sizing and behavior by each breakpoint.

- **Containers center and horizontally pad your content.** Use `.container` for a responsive pixel width, `.container-fluid` for `width: 100%` across all viewports and devices, or a responsive container (e.g., `.container-md`) for a combination of fluid and pixel widths.

- **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 to ensure the content in your columns is visually aligned down the left side. Rows also support modifier classes to [uniformly apply column sizing](#row-columns) and [gutter classes]({{< docsref "/layout/gutters" >}}) to change the spacing of your content.

- **Columns are incredibly flexible.** There are 12 template columns available per row, allowing you to create different combinations of elements that span any number of columns. Column classes indicate the number of template columns to span (e.g., `col-4` spans four). `width`s are set in percentages so you always have the same relative sizing.

- **Gutters are also responsive and customizable.** [Gutter classes are available]({{< docsref "/layout/gutters" >}}) across all breakpoints, with all the same sizes as our [margin and padding spacing]({{< docsref "/utilities/spacing" >}}). Change horizontal gutters with `.gx-*` classes, vertical gutters with `.gy-*`, or all gutters with `.g-*` classes. `.g-0` is also available to remove gutters.

- **Sass variables, maps, and mixins power the grid.** If you don't want to use the predefined grid classes in Bootstrap, you can use our [grid's source Sass](#sass) to create your own with more semantic markup. We also include some CSS custom properties to consume these Sass variables for even greater flexibility for you.

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#flexbug-9).

## Grid options

Bootstrap's grid system can adapt across all six default breakpoints, and any breakpoints you customize. The six default grid tiers are as follow:

- Extra small (xs)
- Small (sm)
- Medium (md)
- Large (lg)
- Extra large (xl)
- Extra extra large (xxl)

As noted above, each of these breakpoints have their own container, unique class prefix, and modifiers. Here's how the grid changes across these breakpoints:

<table class="table mb-4">
  <thead>
    <tr>
      <th scope="col"></th>
      <th scope="col">
        xs<br>
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