Proportion Calculator
Solve a proportion a/b = c/x for the unknown value.
Result
Results are estimates for general information only and are not professional advice.
Solving proportions
A proportion states that two ratios are equal: a/b = c/x. By cross-multiplying, the unknown is x = (b × c) ÷ a. This calculator solves for x instantly — handy for scaling recipes, maps and mixtures.
Frequently Asked Questions
What is the Proportion Calculator?
Solve a proportion a/b = c/x for the unknown value. It runs instantly in your browser and is completely free to use.
What do I need to enter to use the Proportion Calculator?
The Proportion Calculator asks for the following values (3): A, B, C. Fill them in and the result appears immediately — the calculation runs on your own device, so nothing you type is sent to a server.
How accurate is the Proportion Calculator?
The Proportion Calculator uses standard, widely-accepted formulas, so its figures are reliable estimates for everyday planning. They are not a substitute for advice from a qualified professional.
Is the Proportion Calculator free, and do I need an account?
Yes. The Proportion Calculator — and every other calculator on Calculatis — is completely free, with no registration, no download and no limit on how often you use it.