Math & Statistics
Ratio & Proportion Calculator
Updated Sep 3, 2026 Reviewed Sep 3, 2026
Solve a missing proportion value, reduce or scale a ratio, compare two ratios, and convert the result into a unit rate, decimal, and percentage.
Ratios and rates
Choose a ratio task
Result
Calculation summary
Enter values to see the result
Your result, breakdown, assumptions, and warnings will appear here.
Equivalent ratios
Proportion model
Formula
a:b = c:x → x = bc/a
- Reduced ratio
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- Decimal rate
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- Percentage
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How to use this calculator
- 1Choose solve, simplify, scale, or compare.
- 2Enter the required ratio terms.
- 3Review the equivalent ratio and unit rate.
Formula
a:b = c:x → x = b × c ÷ a
Equivalent ratios have equal quotients and cross-products.
Calculation steps
- Interpret each ordered pair as a quotient.
- Apply cross-multiplication, scaling, or reduction.
- Display decimal and percentage equivalents.
Worked example
For 3:4 = 12:x, x = 16.
Assumptions
- Ratio terms are positive.
- Order is significant.
- Decimal ratios are scaled before integer reduction.
Sources
Frequently asked questions
Does ratio order matter?
Yes, 3:2 differs from 2:3.
How is x found?
By cross-multiplying known terms.
Can decimals be simplified?
Yes, they are scaled to integers first.
What is a unit rate?
It expresses the first amount per one second unit.
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