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LunaCalc

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Aspect Ratio Calculator

Simplify an aspect ratio and compute proportional dimensions.

Calculator

About this calculator

This aspect ratio calculator simplifies a width:height pair to its lowest ratio and scales dimensions proportionally.

Formula notes

Divide both dimensions by their GCD; to resize, height = width × (h/w) preserving the ratio.

Worked examples

  1. Example: 1920 × 1080 simplifies to 16:9, and resizing to width 1280 gives height 720.
  2. A 1920 x 1080 frame reduces to 16:9; keeping that ratio at 1280 px wide gives a height of 720 px.

How to use it

  1. Enter the width and height.
  2. Read the simplified ratio like 16:9.
  3. Enter a new width or height to scale proportionally.

Frequently asked questions

Is 16:9 the same as 1.78:1?

Yes. 16/9 ≈ 1.778, both describe the same proportion.

Why do resized images distort?

Changing one side without the other breaks the ratio; scale both together to avoid stretching.

Limits and interpretation

  • Pixel aspect ratio and display aspect ratio can differ in some video formats, while this tool assumes square pixels.
  • Cropping, letterboxing, safe areas, and responsive container constraints are not represented by proportional scaling alone.