Simplify 6 : 9 : 15
The greatest common divisor of 6, 9 and 15 is 3. Divide every part by 3 to get 2 : 3 : 5. No whole number larger than 1 divides all three resulting terms.
Three Number Ratio Calculator
Simplify all three parts of a ratio together. Enter whole numbers or decimals and keep the same order in the result.
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Simplify a three-number ratio
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How to use this calculator
Simplify a ratio containing decimals
For 0.5 : 0.75 : 1.25, multiply every term by 100 to get 50 : 75 : 125. Divide all three by 25 to get 2 : 3 : 5. This calculator keeps decimal reduction exact.
Can one part be zero?
Yes. For 0 : 4 : 6, divide every part by 2 to get 0 : 2 : 3. The ratio 0 : 0 : 0 has no nonzero relationship to simplify and is rejected.
How do I use the resulting ratio?
In 2 : 3 : 5 there are 10 total parts. A total quantity of 100 would be divided into 20, 30 and 50. For the percentage breakdown, use the ratio-to-percentage calculator below.
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About this calculator
Created by Marchelle Cook at Roof & Ratio. Use the worked examples to check the method. If an answer seems incorrect, send us a calculation question or correction.
Guide updated October 16, 2026.