Bootstrap includes a responsive, mobile first fluid grid system that appropriately scales up to 12 columns as the device or viewport size increases. It includes predefined classes for easy layout options, as well as powerful utility classes for showing and hiding content by device via media query
Introduction
Grid systems are used for creating page layouts through a series of rows and columns that house your content. Here's how the Bootstrap grid system works:
Rows must be placed within a .container (fixed-width) or .container-fluid (full-width) for proper alignment and padding.
Use rows to create horizontal groups of columns.
Content should be placed within columns, and only columns may be immediate children of rows.
Predefined grid classes like .row and .col-xs-4 are available for quickly making grid layouts. Less mixins can also be used for more semantic layouts.
Columns create gutters (gaps between column content) via padding. That padding is offset in rows for the first and last column via negative margin on .rows.
The negative margin is why the examples below are outdented. It's so that content within grid columns is lined up with non-grid content.
Grid columns are created by specifying the number of twelve available columns you wish to span. For example, three equal columns would use three .col-xs-4.
If more than 12 columns are placed within a single row, each group of extra columns will, as one unit, wrap onto a new line.
Grid classes apply to devices with screen widths greater than or equal to the breakpoint sizes, and override grid classes targeted at smaller devices. Therefore, e.g. applying any .col-md-* class to an element will not only affect its styling on medium devices but also on large devices if a .col-lg-* class is not present.
Look to the examples for applying these principles to your code.
Grid options
See how aspects of the Bootstrap grid system work across multiple devices with a handy table.
Extra small devices Phones (<768px)
Small devices Tablets (≥768px)
Medium devices Desktops (≥992px)
Large devices Desktops (≥1200px)
Grid behavior
Horizontal at all times
Collapsed to start, horizontal above breakpoints
Container width
None (auto)
750px
970px
1170px
Class prefix
.col-xs-
.col-sm-
.col-md-
.col-lg-
# of columns
12
Column width
Auto
~62px
~81px
~97px
Gutter width
30px (15px on each side of a column)
Nestable
Yes
Offsets
Yes
Column ordering
Yes
Example: Stacked-to-horizontal
Using a single set of .col-md-* grid classes, you can create a basic grid system that starts out stacked on mobile devices and tablet devices (the extra small to small range) before becoming horizontal on desktop (medium) devices. Place grid columns in any .row.
Don't want your columns to simply stack in smaller devices? Use the extra small and medium device grid classes by adding .col-xs-*.col-md-* to your columns. See the example below for a better idea of how it all works.
If more than 12 columns are placed within a single row, each group of extra columns will, as one unit, wrap onto a new line.
.col-xs-9
.col-xs-4 Since 9 + 4 = 13 > 12, this 4-column-wide div gets wrapped onto a new line as one contiguous unit.
.col-xs-6 Subsequent columns continue along the new line.
class="row">class="col-xs-9">.col-xs-9
class="col-xs-4">.col-xs-4 Since 9 + 4 = 13 > 12, this 4-column-wide div gets wrapped onto a new line as one contiguous unit.
class="col-xs-6">.col-xs-6 Subsequent columns continue along the new line.
Responsive column resets
With the four tiers of grids available you're bound to run into issues where, at certain breakpoints, your columns don't clear quite right as one is taller than the other. To fix that, use a combination of a .clearfix and our responsive utility classes.
.col-xs-6 .col-sm-3 Resize your viewport or check it out on your phone for an example.
Move columns to the right using .col-md-offset-* classes. These classes increase the left margin of a column by * columns. For example, .col-md-offset-4 moves .col-md-4 over four columns.
To nest your content with the default grid, add a new .row and set of .col-sm-* columns within an existing .col-sm-* column. Nested rows should include a set of columns that add up to 12 or fewer (it is not required that you use all 12 available columns).
Basic grid layouts to get you familiar with building within the Bootstrap grid system.
Three equal columns
Get three equal-width columns starting at desktops and scaling to large desktops. On mobile devices, tablets and below, the columns will automatically stack.
.col-md-4
.col-md-4
.col-md-4
Three unequal columns
Get three columns starting at desktops and scaling to large desktops of various widths. Remember, grid columns should add up to twelve for a single horizontal block. More than that, and columns start stacking no matter the viewport.
.col-md-3
.col-md-6
.col-md-3
Two columns
Get two columns starting at desktops and scaling to large desktops.
.col-md-8
.col-md-4
Full width, single column
No grid classes are necessary for full-width elements.
Two columns with two nested columns
Per the documentation, nesting is easy—just put a row of columns within an existing column. This gives you two columns starting at desktops and scaling to large desktops, with another two (equal widths) within the larger column.
At mobile device sizes, tablets and down, these columns and their nested columns will stack.
.col-md-8
.col-md-6
.col-md-6
.col-md-4
Mixed: mobile and desktop
The Bootstrap 3 grid system has four tiers of classes: xs (phones), sm (tablets), md (desktops), and lg (larger desktops). You can use nearly any combination of these classes to create more dynamic and flexible layouts.
Each tier of classes scales up, meaning if you plan on setting the same widths for xs and sm, you only need to specify xs.
.col-xs-12 .col-md-8
.col-xs-6 .col-md-4
.col-xs-6 .col-md-4
.col-xs-6 .col-md-4
.col-xs-6 .col-md-4
.col-xs-6
.col-xs-6
Mixed: mobile, tablet, and desktop
.col-xs-12 .col-sm-6 .col-lg-8
.col-xs-6 .col-lg-4
.col-xs-6 .col-sm-4
.col-xs-6 .col-sm-4
.col-xs-6 .col-sm-4
Column clearing
Clear floats at specific breakpoints to prevent awkward wrapping with uneven content.
.col-xs-6 .col-sm-3
Resize your viewport or check it out on your phone for an example.
.col-xs-6 .col-sm-3
.col-xs-6 .col-sm-3
.col-xs-6 .col-sm-3
Offset, push, and pull resets
Reset offsets, pushes, and pulls at specific breakpoints.
See Sony’s Latest Mini-LED Surgical Displays at WHX Miami
Ampronix is proud to partner with Sony Medical as Master Distributor for Sony Medical Monitors.
Join us at WHX Miami to experience Sony’s latest 4K HDR Mini-LED surgical visualization technology.
WHX Miami 2026
June 17 to 19, 2026
Miami Beach Convention Center
Meet with Ampronix and Sony Medical at WHX Miami to discuss Sony M1 surgical displays,
availability, distribution opportunities, and your surgical monitor requirements.
“Ampronix was very helpful and very prompt responding to my inquiries.”
Jimmy
Canon USA
“Asked for a fast repair and they delivered.”
Randy
Mercy Hospital Joplin
“I just wanted to say how helpful Berta was in fixing my problem. I know people are quick to complain but I think it's important to make sure if they do a great job they should be recognized."
Sammy
GE Healthcare
“I would like to again express my gratitude to Ampronix for their help in getting what we needed. It was their guidance that led to a happy end-user. Thank you!”
Jimmy
Radiology Solutions
“Ampronix you are the best and we appreciate all you do for us! Great monitors, easy ordering process with you, tracking numbers always come... Couldn't ask for more in a vendor. THANK YOU!”
Rita
Radiographic Equipment Services
Tell Us About Your Project
Our team is here to help you source, replace, or repair the equipment you need.
Reach out today, or complete the form, and our team will contact you shortly.
