To simplify a ratio, enter its two parts into the Ratio Calculator and it reduces them to lowest terms. To solve a proportion A:B = C:?, enter the three known values and it finds the missing one.
How to use the Ratio Calculator
- Choose simplify or solve for the missing value.
- Enter the numbers.
- Read the simplified ratio or the missing term.
- Check the result by cross-multiplying.
Worked example
The ratio 8:12 simplifies to 2:3. For 2:3 = 10:?, the missing value is 15, because 10 divided by 2 is 5 and 3 times 5 is 15.
Tips and common mistakes
- A ratio is simplified by dividing both parts by their greatest common factor.
- Keep units consistent on both sides of a proportion.
- Cross-multiplication is a quick check: A x ? should equal B x C.
Frequently asked questions
What is a proportion?
An equation stating that two ratios are equal.
Can I use decimals?
Yes, but whole numbers give the cleanest simplified ratios.
Is it private?
Yes. It runs in your browser.