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Bootstrap grid system

Bootstrap grid system is robust flexbox grid to build responsive layouts of all shapes and sizes. Check some examples of Bootstrap grid examples.

How it works

Bootstrap’s grid system uses a set of containers, rows, and columns to layout and align content. It’s developed with flexbox and is fully responsive. Below is a Bootstrap grid system example and an in-depth look at how the grid comes together.

1/3
1/3
1/3
<div class="container">
  <div class="row">
    <div class="col-sm">
      1/3
    </div>
    <div class="col-sm">
      1/3
    </div>
    <div class="col-sm">
      1/3
    </div>
  </div>
</div>

The higher example generates three equal-width columns on small, medium, large, and extra large devices utilizing predefined bootstrap grid css classes. These columns are centered in the content with the parent .container.

Breaking it down, here’s how it works:

  • Containers give 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 for controlling the space between them. This padding is then checked 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.
  • Thankfulness to flexbox, grid columns without a specified width will automatically layout as equal width columns. For example, four examples of .col-sm will each automatically be 25% wide from the small breakpoint and up. See the auto-layout columns section for more examples.
  • Column classes show the number of columns you would like to use out of the potential 12 per row. So, if you need three equal-width columns, you can use .col-4.
  • Column widths 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: 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 for more semantic markup.

Grid options

While Bootstrap uses ems or rems for defining most sizes, pxs are used for bootstrap grid CSS breakpoints and container wideness. It’s because the viewport width is in pixels.

Please notice how aspects of the Bootstrap grid system work across various 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

Use breakpoint-specific column classes for smooth column sizing without an specific 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 an unspecified number of unit-less classes for each breakpoint you need and each column will be the same width.

1/2
1/2
1/3
1/3
1/3
<div class="container">
  <div class="row">
    <div class="col">
      1/2
    </div>
    <div class="col">
      1/2
    </div>
  </div>
  <div class="row">
    <div class="col">
      1/3
    </div>
    <div class="col">
      1/3
    </div>
    <div class="col">
      1/3
    </div>
  </div>
</div>

Setting one column width

Auto-layout for flexbox grid columns also means you can lock the width of one column and have the sibling columns automatically resize around it. You can use predefined grid classes, grid mixins, or inline widths. Remark that the other columns will resize no matter the width of the center column.

1/3
1/3 (col-6)
1/3
1/3
1/3 (col-6)
1/3
<div class="container">
  <div class="row">
    <div class="col">
      1/3
    </div>
    <div class="col-6">
      1/3 (col-6)
    </div>
    <div class="col">
      1/3
    </div>
  </div>
  <div class="row">
    <div class="col">
      1/3
    </div>
    <div class="col-5">
      1/3 (col-6)
    </div>
    <div class="col">
      1/3
    </div>
  </div>
</div>

Variable width content

Apply col-{breakpoint}-auto classes to size columns based on the real width of their content.

1/3
1/3 Some content
1/3
1/3
1/3 Some content
1/3
<div class="container">
  <div class="row justify-content-md-center">
    <div class="col col-lg-2">
      1/3
    </div>
    <div class="col-md-auto">
      1/3 Some content
    </div>
    <div class="col col-lg-2">
      1/3
    </div>
  </div>
  <div class="row">
    <div class="col">
      1/3
    </div>
    <div class="col-md-auto">
      1/3 Some content
    </div>
    <div class="col col-lg-2">
      1/3
    </div>
  </div>
</div>

Equal-width multi-row

Create equal columns that span multiple rows by including 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.

col
col
col
col
<div class="row">
  <div class="col">col</div>
  <div class="col">col</div>
  <div class="w-100"></div>
  <div class="col">col</div>
  <div class="col">col</div>
</div>

Responsive classes

Bootstrap’s grid css includes five layers of predefined classes for developing mixed responsive layouts. Customize the size of your columns on small or large devices nevertheless you see fit.

All breakpoints

For grids that are the equal from the smallest of devices to the largest, use the .col and .col-* classes. Specify a numbered class when you require an individually sized column; otherwise, feel free to stick to .col.

col
col
col
col
col-8
col-4
<div class="row">
  <div class="col">col</div>
  <div class="col">col</div>
  <div class="col">col</div>
  <div class="col">col</div>
</div>
<div class="row">
  <div class="col-8">col-8</div>
  <div class="col-4">col-4</div>
</div>

Stacked to horizontal

Using a single set of .col-sm-* classes, you can create a basic grid system that starts out stacked and becomes horizontal at the small breakpoint (sm).

col-sm-8
col-sm-4
col-sm
col-sm
col-sm
<div class="row">
  <div class="col-sm-8">col-sm-8</div>
  <div class="col-sm-4">col-sm-4</div>
</div>
<div class="row">
  <div class="col-sm">col-sm</div>
  <div class="col-sm">col-sm</div>
  <div class="col-sm">col-sm</div>
</div>

Mix and match

Don’t want your columns to accumulate in some grid tiers simply? Use a mixture of different classes for each tier as needed. See the sample below for a better idea of how does it work.

.col-12 .col-md-8
.col-6 .col-md-4
.col-6 .col-md-4
.col-6 .col-md-4
.col-6 .col-md-4
.col-6
.col-6
<!-- Stack the columns on mobile by making one full-width and the other half-width -->
<div class="row">
  <div class="col-12 col-md-8">.col-12 .col-md-8</div>
  <div class="col-6 col-md-4">.col-6 .col-md-4</div>
</div>

<!-- Columns start at 50% wide on mobile and bump up to 33.3% wide on desktop -->
<div class="row">
  <div class="col-6 col-md-4">.col-6 .col-md-4</div>
  <div class="col-6 col-md-4">.col-6 .col-md-4</div>
  <div class="col-6 col-md-4">.col-6 .col-md-4</div>
</div>

<!-- Columns are always 50% wide, on mobile and desktop -->
<div class="row">
  <div class="col-6">.col-6</div>
  <div class="col-6">.col-6</div>
</div>

Alignment

Use flexbox alignment utilities to vertically and horizontally align columns.

Vertical alignment

One of three columns
One of three columns
One of three columns
One of three columns
One of three columns
One of three columns
One of three columns
One of three columns
One of three columns
<div class="container">
  <div class="row align-items-start">
    <div class="col">
      One of three columns
    </div>
    <div class="col">
      One of three columns
    </div>
    <div class="col">
      One of three columns
    </div>
  </div>
  <div class="row align-items-center">
    <div class="col">
      One of three columns
    </div>
    <div class="col">
      One of three columns
    </div>
    <div class="col">
      One of three columns
    </div>
  </div>
  <div class="row align-items-end">
    <div class="col">
      One of three columns
    </div>
    <div class="col">
      One of three columns
    </div>
    <div class="col">
      One of three columns
    </div>
  </div>
</div>
One of three columns
One of three columns
One of three columns
<div class="container">
  <div class="row">
    <div class="col align-self-start">
      One of three columns
    </div>
    <div class="col align-self-center">
      One of three columns
    </div>
    <div class="col align-self-end">
      One of three columns
    </div>
  </div>
</div>

Horizontal alignment

One of two columns
One of two columns
One of two columns
One of two columns
One of two columns
One of two columns
One of two columns
One of two columns
One of two columns
One of two columns
<div class="container">
  <div class="row justify-content-start">
    <div class="col-4">
      One of two columns
    </div>
    <div class="col-4">
      One of two columns
    </div>
  </div>
  <div class="row justify-content-center">
    <div class="col-4">
      One of two columns
    </div>
    <div class="col-4">
      One of two columns
    </div>
  </div>
  <div class="row justify-content-end">
    <div class="col-4">
      One of two columns
    </div>
    <div class="col-4">
      One of two columns
    </div>
  </div>
  <div class="row justify-content-around">
    <div class="col-4">
      One of two columns
    </div>
    <div class="col-4">
      One of two columns
    </div>
  </div>
  <div class="row justify-content-between">
    <div class="col-4">
      One of two columns
    </div>
    <div class="col-4">
      One of two columns
    </div>
  </div>
</div>

No gutters

The gutters between columns in our predefined grid classes can be eliminated with .no-gutters. This eliminates the negative margins from .row and the horizontal padding from all immediate children columns.

Need an edge-to-edge design? Drop the parent .container or .container-fluid.

.no-gutters {
  margin-right: 0;
  margin-left: 0;

  > .col,
  > [class*="col-"] {
    padding-right: 0;
    padding-left: 0;
  }
}

In usage, here’s how it works. Note you can continue to use this with all different predefined grid classes.

.col-12 .col-sm-6 .col-md-8
.col-6 .col-md-4
<div class="row no-gutters">
  <div class="col-12 col-sm-6 col-md-8">.col-12 .col-sm-6 .col-md-8</div>
  <div class="col-6 col-md-4">.col-6 .col-md-4</div>
</div>

Column wrapping

If more than 12 columns are arranged within a single row, each group of extra columns will, as one unit, wrap on a new line.

.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.
<div class="row">
  <div class="col-9">.col-9</div>
  <div class="col-4">.col-4<br>Since 9 + 4 = 13 &gt; 12, this 4-column-wide div gets wrapped onto a new line as one contiguous unit.</div>
  <div class="col-6">.col-6<br>Subsequent columns continue along the new line.</div>
</div>

Column breaks

Breaking columns to a new line in flexbox needs a small hack: add an element with width: 100% anywhere you want to wrap your columns to a new line. Usually, this is accomplished with many .rows, but not every implementation technique can account for this.

.col-6 .col-sm-3
.col-6 .col-sm-3
.col-6 .col-sm-3
.col-6 .col-sm-3
<div class="row">
  <div class="col-6 col-sm-3">.col-6 .col-sm-3</div>
  <div class="col-6 col-sm-3">.col-6 .col-sm-3</div>

  <!-- Force next columns to break to new line -->
  <div class="w-100"></div>

  <div class="col-6 col-sm-3">.col-6 .col-sm-3</div>
  <div class="col-6 col-sm-3">.col-6 .col-sm-3</div>
</div>

You could also apply this break at specific breakpoints with responsive display utilities.

.col-6 .col-sm-4
.col-6 .col-sm-4
.col-6 .col-sm-4
.col-6 .col-sm-4
<div class="row">
  <div class="col-6 col-sm-4">.col-6 .col-sm-4</div>
  <div class="col-6 col-sm-4">.col-6 .col-sm-4</div>

  <!-- Force next columns to break to new line at md breakpoint and up -->
  <div class="w-100 d-none d-md-block"></div>

  <div class="col-6 col-sm-4">.col-6 .col-sm-4</div>
  <div class="col-6 col-sm-4">.col-6 .col-sm-4</div>
</div>

Reordering

Bootstrap grid 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.

First, but unordered
Second, but last
Third, but first
<div class="container">
  <div class="row">
    <div class="col">
      First, but unordered
    </div>
    <div class="col order-12">
      Second, but last
    </div>
    <div class="col order-1">
      Third, but first
    </div>
  </div>
</div>

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 additionally be intermixed with the numbered .order-* classes as demanded.

First, but last
Second, but unordered
Third, but first
<div class="container">
  <div class="row">
    <div class="col order-last">
      First, but last
    </div>
    <div class="col">
      Second, but unordered
    </div>
    <div class="col order-first">
      Third, but first
    </div>
  </div>
</div>

Bootstrap grid offset

You can offset grid columns in two ways: our responsive .offset- grid classes and our margin utilities. 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.

.col-md-4
.col-md-4 .offset-md-4
.col-md-3 .offset-md-3
.col-md-3 .offset-md-3
.col-md-6 .offset-md-3
<div class="row">
  <div class="col-md-4">.col-md-4</div>
  <div class="col-md-4 offset-md-4">.col-md-4 .offset-md-4</div>
</div>
<div class="row">
  <div class="col-md-3 offset-md-3">.col-md-3 .offset-md-3</div>
  <div class="col-md-3 offset-md-3">.col-md-3 .offset-md-3</div>
</div>
<div class="row">
  <div class="col-md-6 offset-md-3">.col-md-6 .offset-md-3</div>
</div>

In addition to column clearing at responsive breakpoints, you may need to reset offsets. See this in action in the grid example.

.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
<div class="row">
  <div class="col-sm-5 col-md-6">.col-sm-5 .col-md-6</div>
  <div class="col-sm-5 offset-sm-2 col-md-6 offset-md-0">.col-sm-5 .offset-sm-2 .col-md-6 .offset-md-0</div>
</div>

<div class="row">
  <div class="col-sm-6 col-md-5 col-lg-6">.col-sm-6 .col-md-5 .col-lg-6</div>
  <div class="col-sm-6 col-md-5 offset-md-2 col-lg-6 offset-lg-0">.col-sm-6 .col-md-5 .offset-md-2 .col-lg-6 .offset-lg-0</div>
</div>

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.

.col-md-4
.col-md-4 .ml-auto
.col-md-3 .ml-md-auto
.col-md-3 .ml-md-auto
.col-auto .mr-auto
.col-auto
<div class="row">
  <div class="col-md-4">.col-md-4</div>
  <div class="col-md-4 ml-auto">.col-md-4 .ml-auto</div>
</div>
<div class="row">
  <div class="col-md-3 ml-md-auto">.col-md-3 .ml-md-auto</div>
  <div class="col-md-3 ml-md-auto">.col-md-3 .ml-md-auto</div>
</div>
<div class="row">
  <div class="col-auto mr-auto">.col-auto .mr-auto</div>
  <div class="col-auto">.col-auto</div>
</div>

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).

Level 1: .col-sm-9
Level 2: .col-8 .col-sm-6
Level 2: .col-4 .col-sm-6
<div class="row">
  <div class="col-sm-9">
    Level 1: .col-sm-9
    <div class="row">
      <div class="col-8 col-sm-6">
        Level 2: .col-8 .col-sm-6
      </div>
      <div class="col-4 col-sm-6">
        Level 2: .col-4 .col-sm-6
      </div>
    </div>
  </div>
</div>

Sass mixins

If using source Sass files, you have the possibility of using Sass variables and mixins to generate custom, semantic, and responsive layouts. Predefined bootstrap grid classes use the same variables and mixins to implement a whole suite of ready-to-use classes for responsive layouts.

Variables

Variables and maps limit the amount of columns, the gutter width, and the media query point at which to begin floating columns. Use these variables to create the predefined grid classes documented above, as well as for the custom mixins listed below.

$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
);

Mixins

Mixins are used in conjunction with the grid variables to generate semantic CSS for individual grid columns.

// 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);

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.

.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);
  }
}
Main content
Secondary content
<div class="example-container">
  <div class="example-row">
    <div class="example-content-main">Main content</div>
    <div class="example-content-secondary">Secondary content</div>
  </div>
</div>

Customizing the grid

Utilizing Bootstrap’s built-in grid Sass variables and maps, it’s potential to fully customize the predefined grid classes. Adjust the number of tiers, the media query dimensions, and the container widths.

Columns and gutters

The number of grid columns can be changed via Sass variables. $grid-columns is used to produce the widths (in percent) of each individual column while $grid-gutter-width allows breakpoint-specific widths that are divided fairly across padding-left and padding-right for the column gutters.

$grid-columns: 12 !default;
$grid-gutter-width: 30px !default;

Grid tiers

Moving beyond the columns themselves, you may also customize the number of grid tiers. If you required just four grid tiers, you would update the $grid-breakpoints and $container-max-widths to something like this:

$grid-breakpoints: (
  xs: 0,
  sm: 480px,
  md: 768px,
  lg: 1024px
);

$container-max-widths: (
  sm: 420px,
  md: 720px,
  lg: 960px
);

If making any changes to the Sass variables or maps, you’ll have to save your modifications and recompile your project.