Ratio Calculator
Enter three of the four numbers in A : B = C : D and leave one blank to solve the proportion. The simplified ratio is shown too.
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Leave exactly one box blank to solve for it.
How to use the Ratio Calculator
- Enter three of the four values.
- Leave one box blank.
- Click Calculate to solve it.
100% free, no sign-up, and it all runs in your browser — your data never leaves your device.
FAQ
How do I simplify a ratio?
Fill A and B (leave C and D blank) and the calculator shows the ratio reduced to its smallest whole-number form using the greatest common divisor.