Ratio Calculator – Simplify, Scale & Convert Ratios
Use our free Ratio Calculator to simplify ratios, scale them up/down, or solve for missing values in a proportion. Perfect for math homework, cooking recipes, maps, and model designs — fast, accurate, and mobile ready.
Solve the Proportion
Enter three values to calculate the fourth. Leave the field you want to solve for empty.
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How to Use
- The calculator is set up as A : B = C : D.
- Enter any three known values into their respective fields.
- Leave the field for the unknown value empty.
- Click the "Calculate" button to find the missing value.
- The result will automatically appear in the empty field.