Toolstia / Ratio calculator
Ratio calculator
A ratio compares quantities. This tool does the three most common jobs: reduce a ratio such as 12:18:24 to its simplest form, find the missing number in a proportion, and divide a total into parts that follow a ratio.
Enter at least two non-negative numbers separated by colons, spaces or commas. Fractions and decimals work too.
A ratio compares quantities. Simplifying divides every part by their greatest common divisor, so 12:18:24 becomes 2:3:4.
How it works
- Choose simplify, solve a proportion or split a total.
- Enter the numbers.
- Read the result.
Simplifying
Divide every part by their greatest common divisor. 12:18:24 becomes 2:3:4. Ratios written with decimals or fractions are first scaled to whole numbers, so 0.5:1.5:2 becomes 1:3:4.
Solving a proportion
In a : b = c : d, the cross products a × d and b × c are equal. Fill in three boxes and the tool solves the fourth. Example: 2 : 3 = 4 : d gives d = 6.
Splitting a total
Add the parts of the ratio, divide the total by that sum, and multiply by each part. Splitting 100 in the ratio 2:3 gives 40 and 60.
Scaling recipes and maps
Use a proportion to scale a recipe, convert a map distance, or work out a price for a different quantity.
Questions
Can a ratio have zero in it?
Yes in a simple ratio like 0:5. In a proportion, zero cannot be a divisor.
Do I need whole numbers?
No. Decimals and fractions work.
Is anything uploaded?
No. Your numbers stays in your browser and is never sent anywhere.