🖌️ Aspect Ratio Calculator — Resize Width and Height
Enter a width and height to simplify the ratio, or lock a ratio and solve for the missing side. Useful for crops, embeds and responsive layouts.
Input
Result
Result
Details
Private by design. This tool runs entirely in your browser — nothing you enter or add is uploaded to any server.
How it works
- Enter pixel width and height, then press Simplify ratio to reduce them by their greatest common divisor.
- To resize, set the target ratio and one side, then press Height from width or Width from height.
- The decimal form is width divided by height, which CSS uses as the aspect-ratio value.
Examples
- 1920 by 1080 simplifies to 16:9.
- A 16:9 frame that is 1280 wide is 720 high.
- 1080 by 1080 simplifies to 1:1.
Frequently asked questions
How is the ratio simplified?
Both sides are divided by their greatest common divisor, so 1920:1080 becomes 16:9. The visual proportion does not change.
Can I use this for video crops?
Yes. 16:9 is common for widescreen video, 9:16 for vertical stories, 4:5 for portrait posts and 1:1 for square crops.
Are the dimensions sent anywhere?
No. The arithmetic runs locally in the browser.
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