Proportion Calculator
Solves for the missing value in a proportion a:b = c:d.
Lilu Baba's Proportion Calculator solves the classic a:b = c:d relationship for the missing fourth value.
How to use this calculator
- Enter a, b and c from the proportion a : b = c : d.
- The missing value d updates instantly.
d (missing value)
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FAQ
Proportion Calculator — frequently asked questions
d = (b × c) ÷ a, derived from cross-multiplying the proportion a:b = c:d.
Division by zero is undefined — enter a non-zero value for a.