Everyday Life

Aspect Ratio Calculator

Keep proportions when scaling a photo, video or design.

By TheCalcTools Updated Formula checked and tested

Your numbers

Your results

Simplified ratio
Simplified ratio
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New height (px)
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Decimal ratio
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Aspect Ratio Calculator by TheCalcTools

How the Aspect Ratio Calculator works

Enter the original width and height in pixels.

The ratio is simplified by dividing both by their greatest common divisor.

Enter a new width to find the height that keeps proportions.

The formula

Ratio = w ÷ gcd(w, h) : h ÷ gcd(w, h)New height = new width × h ÷ w

Worked example

Using the default values shown in the calculator:

Original width (px)1920
Original height (px)1080
New width (px)1280
  1. gcd(1920, 1080) = 120, so the ratio is 16:9.
  2. A width of 1280 px keeps a height of 720 px.

Result:

Simplified ratio16:9
New height (px)720
Decimal ratio1.7778

Frequently asked questions

What are common aspect ratios?

16:9 for widescreen video, 4:3 for older screens, 3:2 for many cameras and 1:1 for square posts.

What if my image is cropped?

Cropping changes the ratio. Resize first, then crop to the target ratio, or use a ratio-locked tool.

Sources and further reading

Screen Size and PPI CalculatorTurn a diagonal measurement into actual width and height GCD and LCM CalculatorEnter two whole numbers to find their greatest common divisor and least common multiple Percentage CalculatorChoose the question you want answered, enter two numbers, and get the percentage result… Party Food CalculatorPlan quantities for a buffet or sit-down meal without over-buying Reading Time CalculatorHow many hours is that book, and when will you finish?

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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.