Ratio Calculator
Use this calculator to simplify a ratio, convert it to percentages, and generate equivalent ratios.
Tip: Fill none, one, or both optional fields to generate equivalent values.
What does “calcul ratios” mean?
“Calcul ratios” simply means calculating ratios: comparing two quantities to understand their relationship. Ratios are everywhere—budgeting, investing, cooking, fitness, design, and business analytics. If you can calculate ratios quickly, you can make better decisions with less guesswork.
How to calculate a ratio
1) Write the comparison
A ratio compares two values in the form A:B or A/B. For example, if a class has 12 girls and 18 boys, the ratio of girls to boys is 12:18.
2) Simplify using the greatest common divisor (GCD)
To simplify a ratio, divide both parts by the same largest number that divides both values. For 12:18, the GCD is 6. So:
- 12 ÷ 6 = 2
- 18 ÷ 6 = 3
The simplified ratio is 2:3.
3) Build equivalent ratios
Equivalent ratios keep the same proportion. If the ratio is 2:3 and you multiply both terms by 5, you get 10:15. Same relationship, different scale.
Ratio, fraction, and percentage: how they connect
Ratios are closely related to fractions and percentages:
- Ratio as fraction: A:B can be written as A/B.
- Percentage of A in whole: A ÷ (A + B) × 100.
- Percentage of B in whole: B ÷ (A + B) × 100.
Example with 2:3: A is 2/(2+3) = 40%, B is 3/(2+3) = 60%.
Practical examples
Finance and investing
You can compare spending categories (needs:wants), debt-to-income, or savings-to-expenses. Ratios help reveal whether your money habits are balanced.
Cooking and recipes
If a sauce uses oil:vinegar = 1:3, doubling or tripling both terms preserves taste consistency. Ratios make recipe scaling reliable.
Work and productivity
Time allocation ratio (deep work:meetings) can show whether your schedule supports real output. A visible ratio often highlights hidden inefficiencies.
Common mistakes to avoid
- Reversing order: 2:5 is not the same as 5:2.
- Mixing units: Compare compatible units (minutes with minutes, dollars with dollars).
- Not simplifying: 20:30 is valid, but 2:3 is clearer.
- Ignoring context: A “good” ratio depends on goals (budgeting, growth, health, etc.).
Quick ratio workflow
- Collect two comparable numbers.
- Write ratio A:B.
- Simplify with GCD.
- Convert to percentage if needed.
- Create equivalent ratio for planning scenarios.
With the calculator above, you can do all of this in one step and use the results for real-world planning.