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Image sizing

Aspect Ratio Calculator

Calculate aspect ratio from width and height, including reduced ratio and decimal value for images, videos, banners, and canvases.

Last checked: 2026-05-01

Last checked: 2026-05-01 Source: W3C CSS Values and Units Module Found a spec change? Send correction.

Interactive tool

Aspect Ratio Calculator

Reduce width and height into a clean aspect ratio before cropping, resizing, or choosing a design canvas.

Formula aspect ratio = width:height reduced by the greatest common divisor
ExampleInputResult
Full HD 1920 x 1080 px 16:9
Square post 1080 x 1080 px 1:1

Workflow

Use Aspect Ratio Calculator in your sizing workflow

Reduce width and height into a clean aspect ratio before cropping, resizing, or choosing a design canvas.

InputWidth and height
OutputReduced ratio
Best beforeCanvas setup or export
StateBrowser-based calculation
Use the aspect ratio calculator before resizing or cropping. It helps you see whether two formats share the same shape and whether an image will need cropping, padding, or a separate export.

Related

Related pages and tools

Nearby tools

More tools in the PixelMeasures toolkit

FAQ

Common questions

How do I calculate aspect ratio?

Find the greatest common divisor of the width and height, then divide both values by that number.

Why does aspect ratio matter?

If two sizes do not share the same ratio, resizing between them requires cropping, padding, or layout changes.

Can I share selected tool settings?

Some PixelMeasures tools keep selected presets in the URL fragment, so a shared link can reopen useful choices while the main tool page stays focused.

References

Sources and references

Aspect-ratio results are pure geometry based on the entered width and height; W3C CSS unit references support how dimensions are represented in web layouts.

Last checked: 2026-05-01