Ratio Calculator
Simplify ratios to lowest terms and scale a ratio up or down by any factor. — free, fast and private.
Your simplified ratio will appear here.
Example: 12 : 18 simplifies to 2 : 3. Scaled by 5, 2 : 3 becomes 10 : 15.
How to use Ratio Calculator
- Enter the two parts of the ratio (a : b).
- Optionally enter a scale factor.
- Click Calculate to see the simplified ratio and the scaled ratio.
- Use it for recipes, mixing, maps and proportions.
Note: this tool runs in your browser. Nothing is uploaded.
Frequently Asked Questions
How do I simplify a ratio?
Divide both parts by their greatest common divisor. For example, 12 : 18 simplifies to 2 : 3 because both divide by 6.
What does scaling a ratio do?
Multiplying both parts by the same factor keeps the proportion. Scaling 2 : 3 by 5 gives 10 : 15 — the same ratio, bigger numbers.
Can ratios have decimals?
Yes. Enter decimals and the calculator converts them to whole numbers first, then simplifies.
Is my data uploaded anywhere?
No. All calculations run in your browser and your numbers are never sent to a server.