How to use Image Aspect Ratio Calculator

The short answer

To calculate an aspect ratio, enter the width and height: the ratio is reduced by the greatest common divisor (1920×1080 is 16:9), and you can enter a new width or height to get the matching dimension without distortion.

It runs in your browser. What you enter is not uploaded.

How to use it

Enter your values in the fields; defaults show a worked example.

Pick the units or options that apply to you.

Read the result, which updates instantly as you type.

Check the formula note under the result to see exactly how it was worked out.

Limits worth knowing

What is the aspect ratio of 1080×1350? 4:5, the tall portrait size Instagram uses for feed posts.

What aspect ratio is 1280×720? 16:9, the standard widescreen ratio used for HD video and YouTube thumbnails.