Breakpoints are customizable widths that determine how your responsive layout behaves across device or viewport sizes.

Core concepts

Breakpoints are the building blocks of responsive design. Use them to control when your layout can be adapted at a particular viewport or device size.

Available breakpoints

Bootstrap includes six default breakpoints, sometimes referred to as grid tiers, for building responsively. These breakpoints can be customized if you're using our source Sass files.

Breakpoint Class infix Dimensions
X-Small None <576px
Small sm ≥576px
Medium md ≥768px
Large lg ≥992px
Extra large xl ≥1200px
Extra extra large xxl ≥1400px

Each breakpoint was chosen to comfortably hold containers whose widths are multiples of 12. Breakpoints are also representative of a subset of common device sizes and viewport dimensions—they don't specifically target every use case or device. Instead, the ranges provide a strong and consistent foundation to build on for nearly any device.

Media queries

Since Bootstrap is developed to be mobile first, we use a handful of media queries to create sensible breakpoints for our layouts and interfaces. These breakpoints are mostly based on minimum viewport widths and allow us to scale up elements as the viewport changes.


Bootstrap primarily uses the following media query ranges—or breakpoints—in our source Sass files for our layout, grid system, and components.

// Source mixins

// No media query necessary for xs breakpoint as it's effectively `@media (min-width: 0) { ... }`
@include media-breakpoint-up(sm) { ... }
@include media-breakpoint-up(md) { ... }
@include media-breakpoint-up(lg) { ... }
@include media-breakpoint-up(xl) { ... }
@include media-breakpoint-up(xxl) { ... }

// Usage

// Example: Hide starting at `min-width: 0`, and then show at the `sm` breakpoint
.custom-class {
  display: none;
@include media-breakpoint-up(sm) {
  .custom-class {
    display: block;

These Sass mixins translate in our compiled CSS using the values declared in our Sass variables. For example:

// X-Small devices (portrait phones, less than 576px)
// No media query for `xs` since this is the default in Bootstrap

// Small devices (landscape phones, 576px and up)
@media (min-width: 576px) { ... }

// Medium devices (tablets, 768px and up)
@media (min-width: 768px) { ... }

// Large devices (desktops, 992px and up)
@media (min-width: 992px) { ... }

// X-Large devices (large desktops, 1200px and up)
@media (min-width: 1200px) { ... }

// XX-Large devices (larger desktops, 1400px and up)
@media (min-width: 1400px) { ... }


We occasionally use media queries that go in the other direction (the given screen size or smaller):

// No media query necessary for xs breakpoint as it's effectively `@media (max-width: 0) { ... }`
@include media-breakpoint-down(sm) { ... }
@include media-breakpoint-down(md) { ... }
@include media-breakpoint-down(lg) { ... }
@include media-breakpoint-down(xl) { ... }
@include media-breakpoint-down(xxl) { ... }

// Example: Style from medium breakpoint and down
@include media-breakpoint-down(md) {
  .custom-class {
    display: block;

These mixins take those declared breakpoints, subtract .02px from them, and use them as our max-width values. For example:

// X-Small devices (portrait phones, less than 576px)
@media (max-width: 575.98px) { ... }

// Small devices (landscape phones, less than 768px)
@media (max-width: 767.98px) { ... }

// Medium devices (tablets, less than 992px)
@media (max-width: 991.98px) { ... }

// Large devices (desktops, less than 1200px)
@media (max-width: 1199.98px) { ... }

// X-Large devices (large desktops, less than 1400px)
@media (max-width: 1399.98px) { ... }

// XX-Large devices (larger desktops)
// No media query since the xxl breakpoint has no upper bound on its width

Single breakpoint

There are also media queries and mixins for targeting a single segment of screen sizes using the minimum and maximum breakpoint widths.

@include media-breakpoint-only(xs) { ... }
@include media-breakpoint-only(sm) { ... }
@include media-breakpoint-only(md) { ... }
@include media-breakpoint-only(lg) { ... }
@include media-breakpoint-only(xl) { ... }
@include media-breakpoint-only(xxl) { ... }

For example the @include media-breakpoint-only(md) { ... } will result in :

@media (min-width: 768px) and (max-width: 991.98px) { ... }

Between breakpoints

Similarly, media queries may span multiple breakpoint widths:

@include media-breakpoint-between(md, xl) { ... }

Which results in:

// Example
// Apply styles starting from medium devices and up to extra large devices
@media (min-width: 768px) and (max-width: 1199.98px) { ... }

Customizing breakpoints

These breakpoints are customizable via Sass.

Extending the default breakpoints

Use the map-merge function provided by Sass for adding a new breakpoint value to the existing map. Add the following in your $theme config:

$theme: (
    breakpoints: map-merge(
            3xl: 1900px

Override all breakpoints

Create your own breakpoints and override the default values provided by us:

$theme: (
    breakpoints: (
        xs: 0,
        sm: 576px,
        md: 768px,
        lg: 992px,
        xl: 1200px