WDD 131: Dynamic Web Fundamentals

Image Aspect Ratio

Overview

The aspect ratio of an image is the proportional relationship between its width and its height. It is commonly expressed as two numbers separated by a colon, as in 16:9. For example, a 16:9 aspect ratio means that for every 16 pixels of width, there are 9 pixels of height.

When you are working with images on the web, it is important to consider the aspect ratio of the image. If you are using an image in a responsive design, you will want to make sure that the image scales properly as the viewport changes size. If the aspect ratio of the image is not preserved, the image may become distorted or cropped in an undesirable way.

Issues

Aspect Ratio is a test within a Best Practices audit in Lighthouse.

Reference: 📑 Display images with incorrect aspect ratio - Chrome for Developers

Here is an example Lighthouse report from DevTools where an image 🔺displays an incorrect aspect ratio.

Screenshot of an Aspect Ratio Issue from a Lighthouse Audit

How to Fix

There are a few ways to fix an incorrect aspect ratio: