Aspect ratio calculator

Find an aspect ratio, or resize while keeping it.

Formula Screens & design

Aspect ratio

Width ÷ height: ≈ 1.7778

How it works

An aspect ratio is width compared with height. To simplify it, both numbers are divided by their greatest common divisor: 1920 and 1080 share 120, giving 16:9.

To resize, the known side is scaled by the ratio. For a width, height = width × ratio height ÷ ratio width.

Some marketing names are rounded: “21:9” screens are often 64:27 (2560 × 1080) or 43:18 (3440 × 1440).

Formula

Ratio = (W ÷ gcd) : (H ÷ gcd)
H = W × ratio height ÷ ratio width
W = H × ratio width ÷ ratio height

Worked example

1920 × 1080 simplifies to 16:9 (both divided by 120), a decimal ratio of 1.7778. A 16:9 frame 1280 pixels wide is 1280 × 9 ÷ 16 = 720 pixels high.

Questions people ask

What are the common aspect ratios?

16:9 for HD video and most screens, 4:3 for older TVs and many tablets, 3:2 for 35 mm photos, 1:1 for square posts and 9:16 for vertical video.

Is 16:10 the same as 8:5?

Yes. They are the same ratio; 16:10 is the name used for monitors such as 1920 × 1200.