How is the ratio simplified?

Using the greatest common divisor of the rounded width and height.

Can I compute width from a known height?

Currently it computes height from a known width; swap the values to reverse it.

Is the aspect-ratio property widely supported?

Yes, all modern browsers support the CSS aspect-ratio property.

CSS Aspect Ratio Calculator

Simplify ratios and compute matching dimensions.

Works Offline

Privacy First

No Login

No API

Inputs

Width

Height

Known width (px)

Computes the matching height for this width.

Results

Simplified ratio

16 : 9

Decimal ratio

1.7778

Height for 1920px width

1080.00px

Preview 16:9

Generated CSS

aspect-ratio: 16 / 9;

About the CSS Aspect Ratio Calculator

Enter a width and height to get the simplified aspect ratio, decimal ratio, and the matching height for any known width. Includes a live preview box and copy-ready aspect-ratio CSS.

Examples

16:9 at 1920 wide

16 / 9, 1920px

Output

aspect-ratio: 16 / 9; height: 1080px

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Frequently asked questions

Version 1.0.0 · Updated 2026-08-07 · Runs entirely in your browser