Video
Aspect ratio calculator.
Enter a width and height to detect the ratio, or enter one dimension plus a target ratio (16:9, 9:16, 4:3, 21:9 and more) to solve for the other. Everything runs instantly in your browser.
Inputs
Fill in a width, a height, or both. Pick a target ratio if you want the missing dimension solved.
Result
Enter a width and/or height to see the ratio.
How it works
- Auto-detect: with both width and height filled in, the tool reduces them to a simplified ratio (their greatest common divisor) and checks it against common standard ratios (16:9, 4:3, 9:16, 21:9, 1:1, 3:2, 5:4, 16:10, 1.85:1, 2.39:1, and their vertical/portrait equivalents) to name it, or reports it as a custom ratio.
- Solve for the missing dimension: pick a target ratio, enter a width or a height, and the other is computed as
height = width × (ratio height ÷ ratio width)or the equivalent for width. Standard decimal values (16:9 = 1.778, 4:3 = 1.333, 3:2 = 1.5, 5:4 = 1.25, 16:10 = 1.6, 1.85:1 = 1.85, 2.39:1 = 2.39) are taken from the standard reference ratios documented on Wikipedia's aspect ratio reference. - Even-pixel rounding: on by default because H.264/H.265 4:2:0 chroma subsampling needs even dimensions — the same rule this site's own Video Trimmer applies when it re-encodes a clip.
Limits
Pure arithmetic, no upload, no file processing — works for any width/height up to normal integer limits.