A ratio compares two or more quantities, showing how many times one value contains another. It's usually written as A:B, such as 1:2 or 16:9.

How do you solve a ratio for a missing value?

For A:B = C:D, cross-multiply: A times D equals B times C. Enter any three values and solve algebraically for the fourth.

How do you simplify a ratio?

Divide every term in the ratio by their greatest common divisor (GCD). For example, 8:12 simplifies to 2:3 because the GCD of 8 and 12 is 4.

Multiply or divide every term in the ratio by the same number. Scaling 2:3 by 4 gives 8:12; the relationship between the parts stays the same.

Ratio Calculator - Solve, Simplify & Scale Ratios Instantly

R RATIO CALCULATOR

Find a missing value, simplify to lowest terms, or scale a ratio up or down — type your numbers and the answer updates instantly.

LIVE PROPORTION — A : B 1 : 1

Enter any three numbers in A : B = C : D. Leave the unknown one blank.

Reduce any ratio to its lowest whole-number terms.

Multiply a ratio by any factor to enlarge or shrink it proportionally.

Factor