Aspect Ratio Calculator

Find the ratio of any size, or the missing width or height. Free, no sign-up, works in your browser.

Resize keeping the ratio

🔒 100% private — processing happens in your browser. Nothing is uploaded.

How to use the aspect ratio calculator

  1. Enter a width and height to see the simplified ratio, e.g. 1920 × 1080 = 16:9.
  2. Under “Resize”, choose a ratio (or use yours) and type a new width or height.
  3. The missing side is calculated so the picture is not stretched.

Use it for video exports, social media posts (Stories 9:16, Instagram portrait 4:5, link previews 1.91:1), printing photos, or CSS boxes. Keeping the aspect ratio avoids black bars, cropping surprises and squashed faces.

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