Free Proportion Calculator
Solve a/b = c/d for the missing value.
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Inputs
Result
d
12.0000
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Short answer
Solve a/b = c/d for the missing value.
What is the Proportion Calculator?
Solve a/b = c/d for the missing value.
How does the Proportion Calculator work?
Enter the inputs above and read the result.
Formula
Variables
dUnknown term
Explanation
Cross-multiply to isolate the missing term.
Examples
Applications
Advantages
Limitations
Common mistakes
Tips
Related concepts
The Proportion Calculator sits inside the Math Calculators hub, in the algebra & equations cluster. Solving for unknowns and manipulating expressions. Understanding the terms below makes the output easier to interpret and easier to compare against neighbouring measures.
Practical use cases and industry applications
Understanding Proportion
Solve a/b = c/d for the missing value. Within math calculators, proportion belongs to the algebra & equations cluster, where it shares terminology and assumptions with closely related tools.
Learning how proportion is calculated
Cross-multiply to isolate the missing term. Working through the variables one at a time — d — makes the result reproducible by hand and easier to sanity-check.
Using proportion to make a decision
Because outputs depend on the assumptions you enter, run more than one scenario before committing to a figure.
How proportion compares with related measures
equation, root, exponent, logarithm all describe adjacent aspects of algebra & equations. Comparing this calculator's output against those measures — using the related tools listed on this page — prevents a single metric from being read in isolation.
Frequently asked questions
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