Enter the two numbers that make up your ratio in the A and B fields. Press Calculate to see the simplified ratio, decimal equivalents, and a visual bar comparison. If you want to find a missing value in a proportion, use the proportion mode: enter three of the four values and the tool solves for the fourth.
A ratio is a comparison of two quantities. If a recipe calls for 2 cups of flour and 1 cup of sugar, the ratio of flour to sugar is 2:1. That means for every 1 cup of sugar, you use 2 cups of flour.
Order matters in a ratio. The ratio 3:4 is not the same as 4:3. Writing the ratio out of order gives you a completely different comparison. Always read the question carefully to know which quantity goes first.
Equivalent ratios represent the same relationship at different scales. 1:2 and 3:6 and 10:20 are all equivalent. You scale ratios up or down by multiplying or dividing both parts by the same number, just like simplifying fractions.
To check if two ratios are equivalent, simplify both down to their lowest terms and compare. If they match, they are equivalent.
A proportion says two ratios are equal: a/b = c/d. To find a missing value, use cross-multiplication. Multiply the diagonal pairs and set them equal.
| Situation | How Ratios Are Used |
|---|---|
| Recipe scaling | Double or halve every ingredient by the same ratio |
| Map distances | Scale ratio like 1:50,000 converts map to real distance |
| Screen resolution | Aspect ratio like 16:9 describes width to height |
| Mixing paint or concrete | Fixed part ratios ensure consistent results every time |
