Ratio

React Bootstrap 5 Ratio component

Create responsive video or slideshow embeds based on the width of the parent by creating an intrinsic ratio that scales on any device.


Basic example

Use the ratio helper to manage the aspect ratios of external content like <iframe>s, <embed>s, <video>s, and <object>s. These helpers also can be used on any standard HTML child element (e.g., a <div> or <img>). Styles are applied from the parent .ratio class directly to the child.

Wrap any embed, like an <iframe>, in a parent element with .ratio and an aspect ratio class. The immediate child element is automatically sized thanks to our universal selector .ratio > *.


          import React from 'react';
          
          export default function App() {
            return (
              <div className="ratio ratio-16x9">
                <iframe
                  src="https://www.youtube.com/embed/vlDzYIIOYmM"
                  title="YouTube video"
                  allowfullscreen
                ></iframe>
              </div>
            );
          }

        

Aspect ratios

Aspect ratios can be customized with modifier classes. By default the following ratio classes are provided:

1x1
4x3
16x9
21x9

          import React from 'react';
          
          export default function App() {
            return (
              <div>
                <div className="ratio ratio-21x9">
                  <div>21x9</div>
                </div>

                <div className="ratio ratio-16x9">
                  <div>16x9</div>
                </div>

                <div className="ratio ratio-4x3">
                  <div>4x3</div>
                </div>

                <div className="ratio ratio-1x1">
                  <div>1x1</div>
                </div>
              </div>
            );
          }
        

Custom ratios

Each .ratio-* class includes a CSS custom property (or CSS variable) in the selector. You can override this CSS variable to create custom aspect ratios on the fly with some quick math on your part.

For example, to create a 2x1 aspect ratio, set --aspect-ratio: 50% on the .ratio.

2x1

          import React from 'react';
          
          export default function App() {
            return (
              <div className="ratio" style={{aspectRatio: "50%"}}>
                <div>2x1</div>
              </div>
            );
          }
        

This CSS variable makes it easy to modify the aspect ratio across breakpoints. The following is 4x3 to start, but changes to a custom 2x1 at the medium breakpoint.


          .ratio-4x3 {
            @include media-breakpoint-up(md) {
              --aspect-ratio: 50%; // 2x1
            }
          }
        
4x3, then 2x1

          import React from 'react';
          
          export default function App() {
            return (
              <div className="ratio-example ratio ratio-4x3">
                <div>4x3, then 2x1</div>
              </div>
            );
          }
        

Sass map

Within _variables.scss, you can change the aspect ratios you want to use. Here’s an example of the $aspect-ratios map:


          $aspect-ratios: (
            "1x1": 100%,
            "4x3": calc(3 / 4 * 100%),
            "16x9": calc(9 / 16 * 100%),
            "21x9": calc(9 / 21 * 100%)
          );