Math & Conversion
Ratio Calculator
Reduce an A:B ratio and calculate the matching value when you know one side of the proportion.
How to use
Enter the values requested above. Reduce an A:B ratio and calculate the matching value when you know one side of the proportion. The result is calculated in your browser.
Formula
Simplified ratio = A ÷ gcd(A, B) : B ÷ gcd(A, B). Matching B = known A × B ÷ A.
Example
If a 2:3 ratio has A = 10, what is B?
The ratio simplifies to 2:3, so B is 15 when A is 10.
Frequently asked questions
- Can a ratio contain decimal values?
- Yes. The calculator scales decimal inputs before simplifying; precision beyond six decimal places is rejected.
- Are my entries stored?
- No. The calculation runs in your browser, and this page does not save the values you enter.