Ratio Calculator
Simplify ratios, solve for missing values, and compare ratios. Works with 2-part and 3-part ratios.
Simplify a ratio
Simplified ratio
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Solve for missing value — A : B = C : ?
What is Ratio Calculator?
A ratio calculator simplifies ratios to their lowest terms and solves for missing values in proportions. Ratios compare two or more quantities and are widely used in cooking, map reading, finance, engineering, and everyday problem-solving.
How to use
- 1 To simplify a ratio, enter two or three values in the top section — the simplified form appears instantly.
- 2 To solve a proportion (A : B = C : ?), enter A, B, and C in the bottom section to find the missing value D.
- 3 The percentage breakdown of each part of the ratio is shown below the simplified result.
- 4 Leave the third field blank if you only need a 2-part ratio.
Formula
Example calculation
The ratio 6:9 simplifies to 2:3 (GCF is 3). For the proportion 2:3 = 8:?, cross-multiply to get D = (3 × 8) / 2 = 12, so the full ratio is 2:3 = 8:12.
Frequently asked questions
How do you simplify a ratio?
Divide all parts of the ratio by their Greatest Common Factor (GCF). For example, 12:18 simplifies to 2:3 because the GCF of 12 and 18 is 6.
What is the difference between a ratio and a fraction?
A fraction represents a part of a whole, while a ratio compares two or more separate quantities. The ratio 3:5 can be written as the fraction 3/5, but ratios can also compare more than two parts.
How do I solve a missing value in a proportion?
Use cross-multiplication. If A:B = C:D, then A × D = B × C, so D = (B × C) / A.
Can ratios include decimals?
Yes. The simplify section accepts decimal inputs, though ratios are most naturally expressed as whole numbers.
What is a 3-part ratio?
A 3-part ratio compares three quantities simultaneously — for example, mixing paint in a ratio of 1:2:3 means for every 1 part of color A, use 2 of B and 3 of C.