Ratio Calculator

Calculate and simplify ratios. Enter two values to get the simplified ratio, plus each value's share as a percentage.

Enter two values. The calculator divides both by their greatest common divisor to simplify the ratio, and shows each value's share of the total as a percentage.

Simplified ratio
First as %
Second as %

A ratio calculator simplifies a pair of numbers to their smallest whole-number ratio by dividing both by their greatest common divisor, and shows each part's share of the whole.

The maths

  • Find the greatest common divisor (GCD) of the two values
  • Divide both by the GCD to get the simplified ratio
  • Each value ÷ total × 100 = its percentage share

For example, 6 and 9 share a GCD of 3, so the ratio is 6:9 → 2:3.

Examples

  • 6 : 9 → 2 : 3
  • 10 : 15 → 2 : 3 (40% : 60%)
  • 100 : 25 → 4 : 1

Frequently asked questions

Does it work with decimals?

The values are rounded to whole numbers before finding the GCD, so very small decimals are best scaled up first. For exact decimal ratios, multiply both by a power of ten before entering.

What if I enter zero?

If either value is zero the GCD is treated as 1 to avoid a divide-by-zero, and the percentage shares are shown as zero where the total is zero.

Just for the giggles, much love.
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