Ratio Calculator
Calculate ratios, proportions, and scale factors. Simplify ratios, solve proportions, and convert ratios to fractions and percentages. Perfect for math problems and real-world applications.
Ratio Calculator
Ratio Results
Enter values to calculate ratio
About the Ratio Calculator
Our free ratio calculator simplifies ratios, solves proportions (find the missing value), calculates scale factor, and converts ratios to fractions and percentages. Ratios compare two or more quantities (e.g. 3:2 or 4:6:8). Use it for recipes, scale drawings, finance, and maths. Simplify to lowest terms, solve A:B = C:D for the unknown, or express the ratio as a fraction or percentage. For percentages alone, use our percentage calculator. For fractions, try our fraction calculator.
Frequently Asked Questions About Ratios
How do I simplify a ratio?
Divide both parts by their greatest common divisor (GCD). For example, 6:9 simplifies to 2:3. This calculator does it automatically.
What is a proportion?
A proportion is an equation of two equal ratios (e.g. A:B = C:D). If you know three values, you can find the fourth. Choose "Solve Proportion" and enter the known values.
How do I convert a ratio to a percentage?
Use the ratio as a fraction (e.g. 3:4 → 3/4) and multiply by 100. So 3:4 = 75%. The calculator shows this when you choose "Convert Ratio".
How the Ratio calculator works
This free ratio calculator runs entirely in your browser using standard mathematical formulas. Enter your figures, tap Calculate, and results update instantly — no signup required.
Figures are estimates for general information. Always verify important decisions with a qualified professional where relevant.
- Input your values using the fields above (numeric keypad on mobile).
- Results use precise floating-point arithmetic rounded for display.
- Refresh or change inputs and recalculate anytime.
Worked example
- Choose typical values for a common ratio scenario.
- Enter those values in the calculator fields above.
- Tap Calculate and compare the on-screen result with the expected formula outcome.
- Adjust one input at a time to see how the result changes.