Ratio calculator
Reduce a ratio to its simplest whole-number form, so 12:18 becomes 2:3. It helps with recipes, paint mixing, map scales and classroom ratio problems.
- Runs in your browser
- Free, no account needed
- Copy or download the result
Result
Example
12:18
Simplified ratio: 2:3
How to use the ratio calculator
- Type two numbers separated by a colon, such as 12:18.
- Each side can be a whole number, a decimal or a fraction, such as 1.5:2 or 1/2:3/4.
- Press Run to get the simplified ratio.
- Press Copy result or Download to keep it.
How it works
Both sides are turned into exact fractions, scaled up to whole numbers, then divided by their greatest common divisor.
Decimals and fractions give whole-number results. For example, 1.5:2 simplifies to 3:4, and 1/2:3/4 simplifies to 2:3.
Negative numbers are allowed. The sign is moved so the second number is never negative.
At least one side must be nonzero. A side with a zero denominator, such as 1/0, is rejected.
Each number can have up to 80 digits, and e notation like 2.5e3 is accepted.
Everything runs in your browser. Your input is not uploaded or stored.
Questions and answers
How do you simplify a ratio?
Divide both numbers by their greatest common divisor. For 12:18 the greatest common divisor is 6, so the ratio becomes 2:3.
How do I simplify a ratio with decimals?
Multiply both sides by the same power of ten to clear the decimals, then simplify. The tool does this for you, so 0.75:2 becomes 3:8.
Can I simplify a ratio with three parts?
Not with this tool. It takes exactly two numbers separated by one colon.
Is my input kept private?
Yes. The ratio is simplified locally in your browser and is not uploaded.