Ratio
Relative comparison of values.
What does Ratio mean?
A ratio is a way to compare two quantities by showing how many times one value contains or is contained within the other. Ratios are used everywhere — from cooking recipes and map scales to financial analysis and screen aspect ratios. Simplifying a ratio makes it easier to understand and compare by dividing both values by their greatest common divisor (GCD).
How to calculate Ratio
To simplify a ratio A:B, find the greatest common divisor (GCD) of A and B using the Euclidean algorithm, then divide both values by it. For example, the ratio 12:8 has a GCD of 4, so the simplified ratio is 3:2. The decimal form is A / B (e.g., 12 / 8 = 1.5). The percentage split is calculated as A / (A + B) × 100 and B / (A + B) × 100 — so 12:8 gives 60% and 40%.
FAQ
Simplifying a ratio means dividing both values by their greatest common divisor (GCD) so the ratio is expressed in the smallest possible whole numbers. For example, 20:15 simplifies to 4:3 because the GCD of 20 and 15 is 5.
A ratio compares two quantities to each other (A:B), while a fraction represents a part of a whole (A/B). The ratio 3:2 means "3 parts to 2 parts," whereas the fraction 3/2 means "3 divided by 2." They are closely related — every ratio can be expressed as a fraction and vice versa.
Yes, ratios can involve decimal numbers (e.g., 2.5:1). However, simplified ratios are typically expressed as whole numbers. To convert a decimal ratio to whole numbers, multiply both sides by a power of 10 to eliminate decimals, then simplify.
Ratios are used in cooking (ingredient proportions), finance (debt-to-equity, price-to-earnings), maps and models (scale ratios), screens (aspect ratios like 16:9), mixing (paint, concrete), and statistics (odds and rates). They help compare quantities in a clear, standardized way.
An aspect ratio describes the proportional relationship between the width and height of a display or image. Common aspect ratios include 16:9 (widescreen), 4:3 (traditional TV), and 21:9 (ultrawide). It is simply a ratio applied to screen or image dimensions.
Related calculators
- Proportion— Equality of two ratios.
- GCD / LCM— Divisor and multiple calculations.
- Percentage Change— Relative increase or decrease.
- Factorial— Product of descending integers.