Math
Simplify a ratio to its lowest terms, or solve for a missing value in a proportion.
Result
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Enter numbers above
Simplifying 45:60 divides both sides by their greatest common divisor, 15, giving 3:4. For a proportion like "if 3 workers take 12 days, how many days for 4 workers" (solved differently, but structurally similar to 3:12 = 4:?), the Solve mode cross-multiplies and divides automatically — (12 × 4) ÷ 3 = 16 — without you needing to set up the cross-multiplication by hand.
Recipe scaling, paint or concrete mixing ratios, map scales, and unit price comparisons are all ratio problems wearing different clothes. Getting comfortable simplifying and solving them quickly saves real time on tasks that otherwise involve stopping to do algebra by hand.
Divide both numbers by their greatest common divisor. 12:18 simplifies to 2:3 because 6 divides evenly into both — this calculator does that step automatically.
Cross-multiply and divide: multiply the second and third numbers together, then divide by the first. For 4:9 = 20:?, that's (9 × 20) ÷ 4 = 45. Use the "Solve" tab above for this.
A ratio compares two separate quantities (like 3 red marbles to 2 blue ones), while a fraction represents a part of a whole. They use similar math, but a ratio doesn't need to add up to a "total" the way a fraction's numerator and denominator do.