Reduce a ratio
Aspect ratio calculator
Enter any positive width and height. AspectFit reduces them to exact whole-number terms and shows the decimal ratio.
How to calculate an aspect ratio
Width comes first
Aspect ratio = width : height. The decimal ratio is width ÷ height. Use the same unit for both dimensions.
Reduce both terms together
For 1920 × 1080, the greatest common divisor is 120. Divide both terms by 120: 1920:1080 = 16:9, or about 1.7778 as a decimal.
Find a missing dimension
New height = new width × source height ÷ source width. For width 1280 at 16:9, height = 1280 × 9 ÷ 16 = 720.
Canonical server calculation