description: Containers are a fundamental building block of Bootstrap that contain, pad, and align your content withing a given device or viewport.
group: layout
toc: true
---
## How they work
Containers are the most basic layout element in Bootstrap and are **required when using our default grid system**. Containers are used to contain, pad, and (sometimes) center the content within them. While containers *can* be nested, most layouts do not require a nested container.
Bootstrap comes with three different containers:
-`.container`, which sets a `max-width` at each responsive breakpoint
-`.container-fluid`, which is `width: 100%` at all breakpoints
-`.container-{breakpoint}`, which is `width: 100%` until the specified breakpoint
The table below illustrates how each container's `max-width` compares to the original `.container` and `.container-fluid` across each breakpoint.
See them in action and compare them in our [Grid example]({{< docsref "/examples/grid#containers" >}}).
<tableclass="table text-left">
<thead>
<tr>
<th></th>
<th>
Extra small<br>
<spanclass="font-weight-normal"><576px</span>
</th>
<th>
Small<br>
<spanclass="font-weight-normal">≥576px</span>
</th>
<th>
Medium<br>
<spanclass="font-weight-normal">≥768px</span>
</th>
<th>
Large<br>
<spanclass="font-weight-normal">≥992px</span>
</th>
<th>
X-Large<br>
<spanclass="font-weight-normal">≥1200px</span>
</th>
<th>
XX-Large<br>
<spanclass="font-weight-normal">≥1400px</span>
</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>.container</code></td>
<tdclass="text-muted">100%</td>
<td>540px</td>
<td>720px</td>
<td>960px</td>
<td>1140px</td>
<td>1320px</td>
</tr>
<tr>
<td><code>.container-sm</code></td>
<tdclass="text-muted">100%</td>
<td>540px</td>
<td>720px</td>
<td>960px</td>
<td>1140px</td>
<td>1320px</td>
</tr>
<tr>
<td><code>.container-md</code></td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<td>720px</td>
<td>960px</td>
<td>1140px</td>
<td>1320px</td>
</tr>
<tr>
<td><code>.container-lg</code></td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<td>960px</td>
<td>1140px</td>
<td>1320px</td>
</tr>
<tr>
<td><code>.container-xl</code></td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<td>1140px</td>
<td>1320px</td>
</tr>
<tr>
<td><code>.container-xxl</code></td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<td>1320px</td>
</tr>
<tr>
<td><code>.container-fluid</code></td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
<tdclass="text-muted">100%</td>
</tr>
</tbody>
</table>
## Default container
Our default `.container` class is a responsive, fixed-width container, meaning its `max-width` changes at each breakpoint.
{{<highlighthtml>}}
<divclass="container">
<!-- Content here -->
</div>
{{</highlight>}}
## Responsive containers
Responsive containers allow you to specify a class that is 100% wide until the specified breakpoint is reached, after which we apply `max-width`s for each of the higher breakpoints. For example, `.container-sm` is 100% wide to start until the `sm` breakpoint is reached, where it will scale up with `md`, `lg`, `xl`, and `xxl`.
{{<highlighthtml>}}
<divclass="container-sm">100% wide until small breakpoint</div>
<divclass="container-md">100% wide until medium breakpoint</div>
<divclass="container-lg">100% wide until large breakpoint</div>
<divclass="container-xl">100% wide until extra large breakpoint</div>
<divclass="container-xxl">100% wide until extra extra large breakpoint</div>
{{</highlight>}}
## Fluid containers
Use `.container-fluid` for a full width container, spanning the entire width of the viewport.
{{<highlighthtml>}}
<divclass="container-fluid">
...
</div>
{{</highlight>}}
## Sass
As shown above, Bootstrap generates a series of predefined container classes to help you build the layouts you desire. You may customize these predefined container classes by modifying the Sass map (found in `_variables.scss`) that powers them:
For more information and examples on how to modify our Sass maps and variables, please refer to [the Sass section of the Grid documentation]({{< docsref "/layout/grid#sass" >}}).