⚖️ Ratio Calculator
Use this for recipes, scale drawings, mixing and screen sizes. Enter A and B to simplify, and C to find the matching value.
Ratio
How the Ratio Calculator works
A ratio is simplified by dividing both sides by their greatest common factor. For a proportion, cross-multiply: A × x = B × C.
Simplify: A : B = (A ÷ GCF) : (B ÷ GCF)
Proportion: A : B = C : x → x = B × C ÷ A
Step-by-step calculation
- 1Enter A and B.
- 2Divide both by their GCF to simplify.
- 3Cross-multiply to solve A:B = C:x.
Worked example
4 : 6 simplifies to 2 : 3. If 4 : 6 = 10 : x, then x = 6 × 10 ÷ 4 = 15.
Ratio Calculator examples
| A | Ratio |
|---|---|
| 2 | 1 : 3 |
| 3 | 1 : 2 |
| 4 | 2 : 3 |
| 5 | 5 : 6 |
| 6 | 1 : 1 |
Other inputs kept at the calculator's default values. Results calculated by this calculator.
Why use a Ratio Calculator?
Scale recipes, maps, models and mixtures.
Important factors that can affect your results
- Order of the ratio matters.
- Units must match.
- Decimals in ratios.
Frequently asked questions
Can ratios have decimals?
Yes. For simplifying, the calculator scales decimals to whole numbers first.
What does 16:9 mean for screens?
For every 16 units of width there are 9 units of height.
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Last reviewed November 2026 · How we build and check our tools · Report a problem