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.

Detailed documentation and more examples of Bootstrap Responsive breakpoints you can find in our Bootstrap Media queries Docs and Bootstrap Grid Examples Docs

Responsive breakpoints for Bootstrap 4

// [ xs ] Extra small devices (portrait phones, less than 576px)
// No media query since this is the default in Bootstrap

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

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

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

// [ xl ] Extra large devices (large desktops, 1200px and up)
@media (min-width: 1200px) { ... }