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What are Bootstrap breakpoints? (A Guide to Responsive Design)
What are Bootstrap breakpoints? (A Guide to Responsive Design)
Bootstrap breakpoints are predefined minimum viewport widths (xs

Bootstrap breakpoints are predefined screen widths that trigger changes in your layout—like switching from a stacked mobile view to a multi-column desktop design. They’re the foundation of Bootstrap’s responsive grid system.
How Bootstrap breakpoints work
Bootstrap uses six breakpoints, each tied to a CSS class prefix (like sm, md, lg). These correspond to minimum viewport widths. When the browser width hits or exceeds a breakpoint, styles for that tier—and all larger ones—apply.
For example, col-md-6 means “use 6 out of 12 columns starting at the medium breakpoint (768px) and up.” Smaller screens ignore it unless you also specify col-sm-12.
The six default breakpoints
As of Bootstrap 5, the breakpoints are:
- xs (extra small): col-6)
-
sm (small): ≥576px —
col-sm-6 -
md (medium): ≥768px —
col-md-6 -
lg (large): ≥992px —
col-lg-6 -
xl (extra large): ≥1200px —
col-xl-6 -
xxl (extra extra large): ≥1400px —
col-xxl-6
Using breakpoints in practice
You don’t need to use all of them. Start with the smallest layout you want to support, then add classes only where the design needs to change.
A common pattern:
-
col-12 col-md-6 col-lg-4→ full-width on phones, two columns on tablets, three on desktops -
d-none d-md-block→ hide an element on phones, show it from tablet up -
text-center text-md-start→ center text on mobile, left-align on medium screens
Customizing breakpoints
You can override defaults in Sass by editing $grid-breakpoints. For example, change md from 768px to 800px—or add a new one like xl2 at 1600px. Then recompile Bootstrap or use a custom build.
If you’re using Bootstrap via CDN or precompiled CSS, stick to the defaults—or supplement with your own media queries.
Basically, breakpoints let you build one set of HTML that adapts smoothly across devices—not by guessing screen sizes, but by responding to real viewport conditions. They’re not magic, but they’re well-tested and flexible enough for most projects.
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