Solve a proportion for an unknown value using cross-multiplication.
Last updated: June 2026 | By Patchworkr Team
Proportion
Result
If two ratios are equal, their cross-products are equal. That lets us solve for the missing value without dividing both sides by a fraction.
Can a be zero?
No. If a is zero, the proportion cannot be solved by this rule.
Does it accept decimals?
Yes. Decimal and scientific-notation values are supported.
What if the input is invalid?
Invalid input is rejected instead of being treated as zero.
What does the formula do?
It uses x = (b × c) / a, which comes from a/b = c/x.
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