Bootstrap includes a powerful mobile-first flexbox grid system for building layouts of all shapes and sizes. It’s based on a 12 column layout and has multiple tiers, one for each media query range. You can use it with Sass mixins or our predefined classes.

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

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 your site’s contents. Use .container for fixed width or .container-fluid for full width.
  • Rows are horizontal groups of columns that ensure your columns are lined up properly. We use the negative margin method on .row to ensure all your content is aligned properly down the left side.
  • Content should be placed within columns, and only columns may be immediate children of rows.
  • Thanks to flexbox, grid columns without a set width will automatically layout with equal widths. For example, four instances of .col-sm will each automatically be 25% wide for small breakpoints.
  • 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, you can use .col-sm-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.
  • There are five grid tiers, one for each responsive breakpoint: all breakpoints (extra small), small, medium, large, and extra large.
  • Grid tiers are based on minimum widths, meaning they apply to that one tier and all those above it (e.g., .col-sm-4 applies to small, medium, large, and extra large devices).
  • You can use predefined grid classes or Sass mixins for more semantic markup.
Extra small
Extra large
Grid behavior Horizontal at all times Collapsed to start, horizontal above breakpoints
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
Offsets Yes
Column ordering Yes