What is an aspect ratio?

An aspect ratio is the proportional relationship between a width and a height, expressed as W:H (e.g. 16:9). It describes shape without specifying size.

How do I find the aspect ratio of an image?

Enter the image's width and height in the 'Source dimensions' panel. The tool divides both by their greatest common divisor to produce the simplest whole-number ratio.

How is the missing dimension calculated?

Given a ratio W:H and a known width, height = width × (H / W). Given a known height, width = height × (W / H).

What is the 16:9 aspect ratio used for?

16:9 (widescreen) is the standard for HDTV, most YouTube videos, and modern monitors. It is also used for presentations and desktop wallpapers.

What does 'simplify ratio' mean?

Simplifying divides both W and H by their GCD. For example, 1920×1080 simplifies to 16:9 because GCD(1920, 1080) = 120, and 1920÷120 = 16, 1080÷120 = 9.

Aspect Ratio Calculator

Calculators· 17 tools

Free aspect ratio calculator for designers and developers. Lock an aspect ratio (e.g. 16:9) and enter one dimension to get the other — or paste a source width and height to compute and simplify the ratio. Supports common presets (16:9, 4:3, 21:9, 1:1, 3:2, 9:16) and works entirely in your browser with no backend required.

Ratio

16:9

Scale — lock ratio, find missing dimension

Width (px)

Height (px)

1920 × 1080

Simplify — reduce W×H to simplest ratio

Source width

Source height

16:9

1920 × 1080 → 16:9

Frequently Asked Questions

References

Aspect ratio — Wikipedia — Wikipedia

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Frequently Asked Questions

References and sources

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