Ratio Calculator
Simplify ratios and solve proportions. Enter A:B to simplify, or find a missing value in A:B = C:D.
Simplify a Ratio
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Solve a Proportion (A : B = C : ?)
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How to Simplify a Ratio
Divide both values by their GCF.
A : B → (A / GCF) : (B / GCF)
6 : 9 → GCF = 3 → 2 : 3
Solving Proportions
A/B = C/D → D = (B × C) / A
2 : 5 = 8 : ? → D = (5 × 8) / 2 = 20
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Last updated: 2026-08-08