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Aspect Ratio Calculator

Solve the missing width, height or ratio from any two values and scale to a target size.

Solve an aspect ratio

Ratio: —
Decimal: —
Solved value: —
Scaled pair: —
Fractions are reduced with the greatest common divisor; all maths runs in your browser.

How to use the Aspect Ratio Calculator

  1. Pick the value you want to solve: height, width or the ratio itself.
  2. Enter the two values you already know, or choose one of the common ratios.
  3. Set a target width or height to see the scaled pair and the full ratio table.

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Frequently Asked Questions

Common questions about the free online aspect ratio calculator.

An aspect ratio describes the relationship between width and height, written as two numbers such as 16:9 or 4:3.
Choose the height mode, enter the width and the ratio, and the tool divides the width by the ratio decimal for you.
The width and height are scaled to whole numbers, then divided by their greatest common divisor to give the smallest pair.
The decimal is the width divided by the height. A 16:9 video has a decimal of about 1.7778, so it is wider than it is tall.
Use 16:9 for standard HD video, 9:16 for vertical clips, 21:9 for cinema and 1:1 for square social posts.
Yes. Enter the target width and the tool returns the matching height so the image keeps exactly the same proportions.
No. Every calculation happens locally in your browser and nothing is transmitted or stored.
Yes. The calculator is fully responsive and works on phones, tablets and desktop browsers alike.

Last updated: October 10, 2026