Ratio & Proportion Calculator
Solve missing proportion terms A:B = C:X and simplify ratios.
Last reviewed by the myCalculator Editorial Team
Input Parameters
Calculation Results
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Formula & How Ratio & Proportion Calculator Works
A proportion states that two ratios are equal, A:B = C:X. Cross-multiplying gives A × X = B × C, so X = (B × C) ÷ A. If a recipe uses 3 parts flour to 4 parts water, then 9 parts flour needs X = (4 × 9) ÷ 3 = 12 parts water. The same method scales map distances, paint mixes, concrete mixes and currency conversions: if 2 units cost 5 dollars, then 6 units cost (5 × 6) ÷ 2 = 15 dollars. Enter the three values you know and leave the unknown as X. Check that all the values use consistent units before you calculate, because a ratio only holds when both sides are measured the same way.
- Enter Term A: Input your target parameter value.
- Enter Term B: Input your target parameter value.
- Enter Term C: Input your target parameter value.
- Apply Formula: Calculate using
X = (B × C) / A. - Review Results: View exact computed answers, metrics, and worked mathematical proofs.
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Frequently Asked Questions (FAQs)
What is a ratio?
A ratio compares the relative sizes of two or more values.
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Authoritative Standards & Verified Reference Citations
Calculations and mathematical logic on this page are grounded in published statutory rules, regulatory standards, and official government data published by the following bodies:
Open government data, scientific datums, and public sector mathematical reference datasets.
Australia's national authority on physical, chemical, and biological metric measurement standards.
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