Fractions & Math Manipulation Tools
Proportion Calculator
Solve a proportion for its missing term with cross-multiplication.
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What is Proportion?
A proportion states that two ratios are equal. Because a/b = c/d cross-multiplies to a × d = b × c, any single missing term can be solved exactly.
How it works
We detect which of the four terms is blank, rearrange the cross-product equation to isolate it, and substitute the known values — exact fractions throughout.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.