Ratio Calculator
Simplify ratios, solve proportions, and find missing values — perfect for cooking, maps, finance, and more.
Enter three known values and leave the unknown as blank (X).
Ratio Calculator – Understand and Apply Ratios
A ratio expresses the relationship between two or more quantities. Ratios are everywhere — in cooking recipes, map scales, financial analysis, engineering designs, and everyday comparisons. Our free Ratio Calculator offers three powerful modes to cover every common ratio problem.
What Is a Ratio?
A ratio compares two values by showing how many times one contains the other. Written as A:B, it tells you the relative size of A compared to B. For example, a ratio of 3:1 means A is three times as large as B.
Simplifying Ratios
To simplify a ratio, divide both values by their Greatest Common Divisor (GCD). For example, 12:8 → GCD is 4 → simplified to 3:2.
Solving Proportions
A proportion states that two ratios are equal: A:B = C:D. If one value is unknown, you can solve by cross-multiplying: A × D = B × C. Rearrange to find the missing variable.
Scaling Ratios
Scaling multiplies both parts of a ratio by the same factor. A 1:3 ratio scaled by 5 becomes 5:15, which still simplifies to 1:3 — the relationship is preserved.
Real-World Uses
- Cooking: Scale recipes up or down while maintaining ingredient ratios.
- Maps: Convert map distances using a scale ratio (e.g., 1:50,000).
- Finance: Debt-to-equity ratios, price-to-earnings, and return ratios.
- Construction: Mix concrete, mortar, or paint with correct component ratios.
Frequently Asked Questions
What is the difference between a ratio and a fraction?
A ratio compares two separate quantities (A:B), while a fraction represents a part of a whole (A/A+B). The ratio 2:3 means out of 5 total parts, A gets 2 and B gets 3.
Can ratios have decimals?
Ratios are typically expressed as whole numbers, but fractions or decimals can arise before simplification. This calculator simplifies to the cleanest integer form.