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Aspect Ratio Calculator

Simplify a width-to-height ratio or calculate matching dimensions without stretching the result. Choose a preset or enter any positive measurements.

Calculate an aspect ratio
Common ratios

Simplified ratio

16:9

Decimal ratio: 1.777778

Calculate proportional dimensions

Enter either a target width or target height. Target width takes priority when both fields contain values.

Proportional dimensions

1,280 × 720

How to calculate proportional dimensions

  1. Enter the original width and height.
  2. Check the simplified ratio or choose a common preset.
  3. Enter a new width or height to calculate its matching dimension.

Rounding to whole pixels may make the final dimensions differ from the exact mathematical ratio by a very small amount. Keep decimals when working with physical measurements or use the nearest whole number for pixel dimensions.

Frequently asked questions

What is an aspect ratio?

An aspect ratio describes the proportional relationship between width and height. A 16:9 image has 16 units of width for every 9 units of height, regardless of its pixel dimensions.

How do I calculate a missing width or height?

Enter the original width and height, then enter either a target width or target height. The calculator uses the original ratio to find the other proportional dimension.

Does an aspect ratio have to use whole numbers?

No. Dimensions can contain decimals, and this calculator scales them before simplifying the ratio. Most published ratios use whole numbers because they are easier to compare.

Does this calculator resize an image file?

No. It calculates proportional dimensions only. Use McStumble’s Image Resizer when you need to change the pixels in an actual image.

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