Aspect Ratio Calculator

Find the ratio of any width and height, and resize while keeping it.

Processed locally — nothing is uploaded

About Aspect Ratio Calculator

Ratios are reduced to their simplest whole-number form, so 1920 by 1080 reports as 16:9 rather than 1920:1080. Dimensions that reduce to something awkward like 137:96 are usually a sign the source was cropped rather than scaled.

An aspect ratio describes the proportional relationship between an image or screen's width and height, written as two numbers like 16:9. This calculator reduces any width×height to its simplest ratio, and — with the ratio locked — lets you change one dimension to instantly get the other, so you can resize without distortion.

It is the quick way to work out dimensions for a video export, a social banner, a print at a fixed proportion or a responsive layout. Common presets — 16:9, 4:3, 1:1 and more — are one click away, and locking one side gives you the other without arithmetic.

Learn how this works

Frequently asked questions

How is the ratio simplified?

The calculator divides both dimensions by their greatest common divisor, so 1920×1080 reduces to 16:9 and 1024×768 to 4:3. This mathematical simplification finds the smallest equivalent ratio, making it easy to understand the proportions at a glance. For example, 800×600 also simplifies to 4:3, confirming that these different pixel dimensions share the same aspect ratio. The simplified ratio is the one you'd use in design tools, video export settings, or when specifying responsive image dimensions.

Can I resize while keeping the same ratio?

Yes. Keep 'Lock aspect ratio' enabled and change either the width or the height; the other dimension updates automatically to preserve the proportions.

Is anything uploaded?

No. Everything runs locally in your browser using standard web APIs — your text, files and inputs are never uploaded to a server, so the tool works even offline once the page has loaded.

More Aspect Ratio Calculator tools

Related tools