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Proportion Calculator

Solve a/b = c/d for any one missing value.

Solve a proportion a/b = c/d for any one of the four values, given the other three.

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

From a/b = c/d: a = bc/d, b = ad/c, c = ad/b, d = bc/a.

In depth

Solve a proportion a/b = c/d for any one of the four values, given the other three.