Aspect Ratio Calculator
Work out the missing width or height for a target ratio.
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Keep images and videos perfectly proportioned. Set an aspect ratio (like 16:9 or 4:3) and enter either the width or the height, and the tool works out the matching dimension. It is ideal for resizing, cropping and designing for screens. The calculation runs live in your browser.
Finding the missing dimension
The everyday problem is knowing one side and needing the other. You have a 16 by 9 video and a container 1280 pixels wide, so what height keeps it from distorting. Or a design needs to be 400 pixels tall at 4 by 3. Getting it wrong stretches faces and skews logos, and it is the kind of error that is obvious to everyone except the person who made it.
The ratios worth remembering
- 16:9 is standard video, YouTube and most screens.
- 9:16 is vertical video: Shorts, Reels and TikTok.
- 1:1 is square, still common for social posts and profile images.
- 4:5 is the tallest ratio Instagram shows in the feed without cropping.
- 1.91:1 is the link preview ratio, which is why Open Graph images are 1200 by 630.
Cropping versus stretching
When an image does not match the ratio you need, you have two options and only one of them is acceptable. Cropping removes part of the picture and keeps everything that remains correctly proportioned. Stretching keeps everything and distorts all of it. Always crop. If the subject will not survive the crop, the honest answer is that you need a different image, not a squashed one.
How to use Aspect Ratio Calculator
- 1
Enter your aspect ratio (e.g. 16:9).
- 2
Type either the width or the height.
- 3
Read the matching dimension.
Frequently asked questions
Yes. Enter any ratio, or pick a common preset like 16:9, 4:3 or 1:1.