Center the content inside a column in Bootstrap

Bootstrap 5 (update 2021)

Since flexbox is still used the centering methods in Bootstrap 5 work the same way. Columns can be centered using offset, auto-margins or justify-content-center (flexbox).

Demo of the Bootstrap 5 Centering Methods

Bootstrap 4 (original answer)

There are multiple horizontal centering methods in Bootstrap 4…

• text-center for center display:inline elements
• offset-* or mx-auto can be used to center column (col-*)
• or, justify-content-center on the row to center columns (col-*)
• mx-auto for centering display:block elements inside d-flex

mx-auto (auto x-axis margins) will center display:block or display:flex elements that have a defined width, (%, vw, px, etc..). Flexbox is used by default on grid columns, so there are also various flexbox centering methods.

Demo of the Bootstrap 4 Centering Methods

In your case, use mx-auto to center the col-3 and text-center to center it’s content..

<div class="row">
    <div class="col-3 mx-auto">
        <div class="text-center">
            center
        </div>
    </div>
</div>

https://codeply.com/go/GRUfnxl3Ol

or, using justify-content-center on flexbox elements (.row):

<div class="container">
    <div class="row justify-content-center">
        <div class="col-3 text-center">
            center
        </div>
    </div>
</div>

Also see:
Vertical Align Center in Bootstrap