Aspect ratio calculator

Find the missing side of a ratio like 16:9, or reduce a resolution to its simplest ratio.

What do you need?
The known side is

Everything is calculated in this browser.

How to use

  1. Pick a preset ratio or enter a custom one.
  2. Enter the known side.
  3. Read the matching dimension.

What it supports

Accepts ratios written as 16:9, 16x9, or 16/9, including decimals. Values are rounded to the nearest pixel — exact results need a side divisible by the ratio.

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