Book 1 · Everyday Math

Ratio & Proportion Solver

Solve a:b = c:d for whichever term is missing. Or switch modes and scale a recipe or mixture from one number of servings to another.

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Fill in any three fields — leave the unknown blank.

Fill in the fields and press Calculate.
From the book — Chapter 4. A proportion says two ratios are equal, and the "cross-multiply" trick just uses that fact: a·d = b·c, so any missing term is one division away. Scaling a recipe is the same idea — every ingredient gets multiplied by (target ÷ original).

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