Proportion Calculator
Solve proportion problems (a/b = c/d) for missing value. Enter three known values and get the fourth.
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isCalculator Editorial Team
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How to use this tool?
How to Use the Proportion Calculator
This calculator solves for one unknown value in a proportion of the form a / b = c / d.
- Enter three known values into the fields labeled a, b, c, and d.
- Leave exactly one field empty — this is the value the calculator will solve for.
- Click the Calculate button (or press Enter).
- The result appears below, showing the solved value and the formula used.
- Use the Clear button to reset all fields and start a new calculation.
Important: Denominators (b and d) cannot be zero. All values can be integers or decimals — no unit conversion is needed.
Previous Results
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Frequently Asked Questions
A proportion is an equation that says two ratios are equal, i.e., a/b = c/d.
Enter three known values and leave the unknown field empty. Click Calculate to get the result.
Yes, you can enter decimal numbers. The calculator will handle them.
