Ratio Calculator

Simplify any ratio A : B to its lowest terms and see it as a decimal.

How ratios work

A ratio compares two quantities by division, written A : B. This calculator simplifies the ratio by dividing both sides by their greatest common divisor.

Enter the two values. The calculator finds the common divisor, reduces the ratio to its simplest whole-number form, and also shows A ÷ B as a decimal where defined.

Ratios are used whenever quantities are compared in proportion — mix ratios, aspect ratios, staffing ratios, win rates. The simplified form makes the relationship easy to read.

The formula

A : B simplified = (A ÷ gcd) : (B ÷ gcd)

Find the greatest common divisor (gcd) of the two values, divide both by it, and write the result as A : B. The decimal interpretation is A ÷ B (undefined when B is zero).

Worked example

The ratio 8 : 12

The greatest common divisor of 8 and 12 is 4, so 8 : 12 simplifies to (8 ÷ 4) : (12 ÷ 4) = 2 : 3. As a decimal, 8 ÷ 12 = 0.67.

Frequently asked questions

What does a simplified ratio mean?

It is the smallest whole-number pair with the same relationship. 2 : 3 and 8 : 12 describe the same proportion; the simplified form is easier to compare.

How do I read the decimal?

The decimal is A ÷ B. For 2 : 3 that is 0.67, meaning A is 67% of B. When B is zero the decimal is undefined because division by zero has no value.

Can a ratio be negative or 0 : 0?

This calculator accepts non-negative values. A ratio of 0 : 0 is undefined and is rejected; 0 : B simplifies to 0 : 1.

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