Ratio Calculator
Simplify a ratio to lowest terms and solve proportions.
Assumptions used in this calculation
- Simplification method: Ratios are reduced using the GCD of the two (or more) terms, same as fraction simplification.
About this calculator
Ratios show up in everything from recipe scaling to map scales to mixing concentrations, but simplifying one to lowest terms or solving for a missing value in a proportion both require finding a greatest common divisor or cross-multiplying correctly, steps that are easy to fumble under time pressure. This calculator takes a ratio a:b, divides both terms by their greatest common divisor to reduce it to lowest terms (4:8 becomes 1:2), and separately solves the proportion a:b = c:x for an unknown fourth term using cross-multiplication (a × x = b × c). It handles both jobs people commonly reach for a ratio calculator to do: cleaning up an odd-looking ratio for a report, and scaling a known ratio up or down to match a new total, without manually working out the GCD or setting up the cross-multiplication by hand.
Worked example
Simplify 4:8, solve 4:8 = 10:x
Result: 1:2, x = 20
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