Bootstrap default media queries

_mixins.scss

@mixin breakpoint($point) {
  @if $point == large {
    @media (min-width: 1200px) { @content; }
  }
  @else if $point == medium {
    @media (min-width: 992px) and (max-width: 1119px) { @content; }
  }
  @else if $point == small {
    @media (min-width: 768px) and (max-width: 991px)  { @content; }
  }
  @else if $point == xsmall {
   @media (max-width: 767px)  { @content; }
  }
}

mixins.less

.breakpoint(@point, @content) when (@point = large) {
  @media (min-width: 1200px) { @content; }
}

.breakpoint(@point, @content) when (@point = medium) {
  @media (min-width: 992px) and (max-width: 1119px) { @content; }
}

.breakpoint(@point, @content) when (@point = small) {
  @media (min-width: 768px) and (max-width: 991px)  { @content; }
}

.breakpoint(@point, @content) when (@point = xsmall) {
  @media (max-width: 767px)  { @content; }
}