Ratio calculator
Simplify a ratio to its lowest terms, find the missing number in a proportion, or share a total out in a given ratio. The working is shown under the answer.
Worked example
With the values shown above when the page opens:
12 : 18 : 30 simplifies to 2 : 3 : 5
- Write the numbers as whole numbers: 12 : 18 : 30
- Find their highest common factor: 6
- Divide each number by 6: 2 : 3 : 5
How it works
- To simplify a ratio, divide every number by their highest common factor.
- A proportion A : B = C : D means the two ratios are equal, so A × D = B × C.
- To split a total, add the ratio numbers to get the number of parts, divide the total by that, and multiply for each share.
Questions
Can a ratio have decimals?
Yes. They are scaled up to whole numbers first, so 1.5 : 2 becomes 15 : 20, which simplifies to 3 : 4.
What is the difference between a ratio and a fraction?
A ratio compares parts to parts (boys : girls = 3 : 5). A fraction compares a part to the whole (3/8 of the class are boys).
How do I share $240 in the ratio 2 : 3 : 5?
There are 10 parts, so one part is $24. The shares are $48, $72 and $120.
Related
Calculators are for learning and quick checks. Check important figures yourself, and do not rely on them for tax, legal or financial decisions.