About the ratio calculator
Ratios describe mixes, scales, and proportions — concrete mixes, fertilizer dilutions, recipe scaling, and map distances. Enter a ratio to simplify it, or add a new first value to scale it and find the matching second value.
How to use this calculator
- Enter A and B.
- Optionally enter C to scale the ratio.
- Read the simplified ratio or the missing value D.
Worked examples
- A = 4, B = 3, C = 20
- D = 3 × 20 ÷ 4 = 15
4 : 3 = 20 : 15.
Measurement guidance
Mix ratios
For a 1 : 4 mix, the total is 5 parts. Divide the batch size by 5 to find one part.
Frequently asked questions
Can ratios have decimals?
Yes for scaling. Simplification works on whole numbers.
What’s the difference between a ratio and a fraction?
A ratio compares parts to each other; a fraction compares a part to a whole.
Do units matter?
Use the same unit for both terms.