Ratio Calculator

Enter A and B to simplify the ratio A:B and to see A divided by B as a decimal.

How it works

A ratio compares two quantities. Simplifying divides both parts by their greatest common divisor after scaling decimals to integers, so 8:12 becomes 2:3 and 2.5:10 becomes 1:4. The decimal is A ÷ B, which is undefined when B is 0 (the simplified form 1:0 is still shown). 0:0 cannot be simplified.

Formula

Simplified A:B = (A ÷ gcd, B ÷ gcd) after scaling decimals to integers
Decimal = A ÷ B

Worked examples

8 and 12 → 2 : 3, decimal 0.666…
2.5 and 10 → 1 : 4, decimal 0.25

Useful notes

This is not a percentage. 2:3 as a percent of a whole would need a different question — use the percentage calculator.

FAQ

How do I simplify a ratio?: Divide both numbers by their greatest common divisor. 8 and 12 share 4, so 8:12 = 2:3.
What does the decimal mean?: It is A divided by B. 2:3 is about 0.6667. It is not “2.3” or a mixed number.
Can one side be zero?: 5:0 simplifies to 1:0; the decimal is undefined. 0:5 becomes 0:1 with decimal 0. 0:0 is rejected.

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