Proportion Calculator

Enter three known values in a proportion (a/b = c/d) to solve for the fourth.

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Formula

d = (b × c) ÷ a

Example

If 2/4 = 3/d, then d = 6.

Frequently Asked Questions

What is a proportion used for?
Proportions are used to scale recipes, maps, currency conversions, and any situation where two ratios must stay equal.