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Online Aspect Ratio Calculator

Enter width and height to get aspect ratio (e.g. 16:9) and the GCD-reduced ratio.

Frequently Asked Questions

What is aspect ratio?
The ratio of width to height (e.g. 16:9 for widescreen). Same ratio means same shape when scaled.
What is GCD-reduced ratio?
Width and height divided by their greatest common divisor so the ratio is in simplest terms (e.g. 1920×1080 → 16:9).
Why use aspect ratio?
For video, images, and screens: to maintain proportions when resizing or to match a target format.

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