Quick guide
How to use the Ratio Calculator
- Enter or choose a, b, c, d (leave blank to solve).
- Select Solve ratio.
- Review the main result, supporting details, and calculation method.
- Copy the result or download generated files when that option is available.
What this tool does
Simplify a ratio or solve an equivalent proportion. Simplification divides both terms by their greatest common divisor; proportion mode uses cross-multiplication to find the missing fourth value.
Calculation method
- Validate the supplied ratio terms and identify whether a proportion value is missing.
- For simplification, divide both terms by their greatest common divisor.
- For a proportion a:b = c:d, solve the missing value while preserving equal cross-products.
Example: solve 4:6 = 10:d
Input: A: 4; B: 6; C: 10; D: blank
Result: Missing value: D = 15
Cross-multiplication gives 4 × d = 6 × 10. Therefore d = 60 ÷ 4 = 15.
Practical uses
- Recipe scaling
- Map and model scales
- Equivalent fractions
- Mixture comparisons
Accuracy tips and common mistakes
- Keep units consistent before comparing quantities.
- A zero term can make division-based proportions undefined.
- A simplified ratio describes relative size, not the original total.