Aspect Ratio Calculator
Given a ratio like 16:9 and one dimension, get the missing width or height instantly — plus presets from 1:1 to 21:9 for video and design.
1,080
1,920 × 1,080 · 1.7778
Ratio fields accept any positive numbers, so 2.35:1 cinema scopes and odd sensor ratios work too.
This tool runs entirely in your browser. Your data never leaves your device — it is not uploaded to any server.
How to use
- 1Pick a ratio preset or type your own width:height values.
- 2Choose which dimension you already know — width or height.
- 3Enter the known value and read the missing dimension.
Aspect Ratio Calculator
Enter a ratio — tap a preset (1:1, 4:3, 3:2, 16:9, 16:10, 21:9) or type custom numbers — then give it a known width or height. The missing dimension appears immediately, together with the pair formatted as W×H and the decimal ratio.
The classic resize without distortion: video crops, responsive image containers, sensor and film formats, print scaling and CSS object-fit decisions all live here, computed locally as you type.
Frequently asked questions
How is the missing dimension calculated?
By direct proportion: known dimension × (target side ÷ matching ratio side). For 16:9 with a width of 1920, height = 1920 × 9 ÷ 16 = 1080. The result is shown rounded, with the exact decimal beneath it.
Why does 16:9 and 16:10 matter so much for screens?
16:9 matches video (1920×1080, 3840×2160) and most monitors; 16:10 adds vertical space for documents and code (1920×1200). Picking the wrong one means letterboxing or stretched pixels — this tool shows exactly what each ratio produces.
Can I use decimal or unusual ratios?
Yes. Both ratio fields accept any positive numbers, so 2.39:1 cinema scope, 1.85:1, 4:5 portrait social crops or sensor sizes like 1.5:1 all work — the proportion math is identical.
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Embed this tool
Put this tool on your own site with one line — it runs entirely in the visitor's browser.
<iframe src="https://zoyku.com/en/tools/aspect-ratio-calculator?embed=1" width="100%" height="640" style="border:0;border-radius:16px" title="Zoyku — aspect-ratio-calculator" loading="lazy"></iframe>