Ratio Calculator
Calculate and simplify ratios with this free online Ratio Calculator. Compare quantities, find equivalent ratios, and solve common ratio problems quickly. Enter your values to get clear results for math homework, recipes, scaling, proportions, and everyday calculations without using a spreadsheet.
A 12:18 ratio to simplify to its lowest terms. Load the example to see the tool in action.
Calculation steps: Divide both parts of 12:18 by their greatest common factor.
What is Ratio Calculator?
Simplify ratios and calculate equivalent ratios with the free Ratio Calculator. Enter two or more supported values to compare quantities, scale ratios and solve common proportion problems. Use it for mathematics, recipes, mixing quantities, measurements and everyday calculations. Get a clear result without manually simplifying values or using a spreadsheet.
Why use this tool?
- Four calculation types in one place: simplify a ratio, find a missing value, scale a ratio and divide a total.
- Each result comes with the calculation steps, so you can check the working or learn the method.
- Decimal inputs are supported when simplifying, so a ratio such as 1.5:2.5 reduces to 3:5.
How to use Ratio Calculator
- Step 1. Choose the calculation type: simplify a ratio, find a missing value, scale a ratio or divide a total.
- Step 2. Enter the two ratio parts, A and B. For a missing value, also enter the known value C. For scaling, enter a multiplier. For dividing, enter the total.
- Step 3. Read the result and the calculation steps shown beneath it.
Common use cases
Important notes
- Order matters: 2:3 and 3:2 are different ratios.
- To find a missing value in A:B = C:x, the tool cross-multiplies, so x = C × B ÷ A. The first part, A, cannot be zero.
- Dividing a total needs non-negative parts that are not both zero. For example, 100 split 2:3 gives 40 and 60.
- When simplifying decimals, the tool scales values by up to six decimal places before reducing.
More Calculators Tools
Ratio Calculator FAQ
How do I simplify a ratio?
Divide both parts by their greatest common factor. For 12:18 the factor is 6, so the simplified ratio is 2:3.
How do I find a missing value in a proportion?
Cross-multiply. For 3:4 = 9:x, multiply 9 by 4 and divide by 3 to get x = 12.
How do I divide a number in a given ratio?
Add the ratio parts, divide the total by that sum, then multiply by each part. Splitting 100 in the ratio 2:3 gives 40 and 60.
Can I use decimals?
Yes. Decimals work in every mode. When simplifying, the tool scales decimals up to six places before reducing them.