Variables determine the number of columns the gutter width and the media query point at which to begin floating columns.
Bootstrap gutter width 1170.
With the responsive css file added the grid adapts to be 724px and 1170px wide depending on your viewport.
Each column has some horizontal padding called a gutter for controlling the space between them.
While bootstrap uses ems or rems for defining most sizes pxs are used for grid breakpoints and container widths.
Less mixins and variables.
The bootstrap 4 grid system has five classes col extra small devices screen width less than 576px col sm small devices screen width equal to or greater than 576px col md medium devices screen width equal to or greater than 768px col lg large devices screen width equal to or greater than 992px col xl xlarge devices screen width equal to or greater than 1200px.
Attached it says all gutters get width of 30px 15 on each side.
In addition to prebuilt grid classes for fast layouts bootstrap includes less variables and mixins for quickly generating your own simple semantic layouts.
100 across all viewport and device sizes.
The default bootstrap grid system utilizes 12 columns making for a 940px wide container without responsive features enabled.
That makes design area 1140 940 and 720 according this.
See how aspects of the bootstrap grid system work across multiple devices with a handy table.
I see most sites designed in a container of 1200 with design canvas at 1170.
Sachin verma jul 25 16 at 12 32.
Use the class container for fixed width or container fluid for variable width.