Ratio & Proportion Calculator
Simplify a ratio, split a total in that ratio and solve a proportion A/B = C/X.
Quick answer
A ratio compares two quantities, simplified by dividing both terms by their greatest common divisor. For a proportion A/B = C/X, cross-multiply to get X = B x C / A; totals split by the ratio terms divided by their sum.
Ratio & Proportion Calculator
X is solved for you.
Simplified Ratio
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Greatest Common Divisor
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A ÷ B
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Share of Total for A
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Share of Total for B
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Solved X (A/B = C/X)
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Share of the whole
Equivalent Ratios
| Multiple | A | B |
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Assumptions & method
- Simplified ratio: both terms are multiplied by 10^d (d = the larger number of decimal places, up to 6) to give whole numbers, then divided by their GCD.
- Shares of a total T: A-share = T × A ÷ (A + B), B-share = T × B ÷ (A + B).
- Proportion A/B = C/X is solved by cross-multiplying: X = B × C ÷ A. It needs A above zero.
- Terms must be zero or more, written as plain decimals (no exponent notation), and not both zero.
- Ratios compare quantities in the same units. Rounding applies only to the displayed decimals.
Results are estimates based on the figures you enter. They are not guarantees and not financial advice.
Ratios and proportions
A ratio compares two quantities, such as 12:18, and is usually easier to read in lowest terms, here 2:3. Simplifying means dividing both parts by their greatest common divisor, and decimals can be handled by scaling both numbers up to whole numbers first. Once you have a ratio you can use it in two common ways. You can split a total into parts that follow the ratio, as with sharing costs or mixing ingredients. Or you can solve a proportion, where two ratios are equal and one term is unknown, by cross-multiplying. This calculator does all three from the same two ratio terms.