How to use the fraction calculator
Put the top number (numerator) and bottom number (denominator) of each fraction in the boxes. For a mixed number such as 1½, also fill in the Whole box. Leave it empty for a plain fraction. For a whole number on its own, fill in only the Whole box.
The answer is shown three ways: as a simplified fraction, as a mixed number when it is bigger than one, and as a decimal.
The formula
- Add or subtract: rewrite both fractions over a common bottom number, then add or subtract the top numbers.
- Multiply: multiply the tops together and the bottoms together.
- Divide: flip the second fraction upside down, then multiply.
- Simplify: divide top and bottom by their greatest common divisor.
Worked example
To add ½ and ⅓, the lowest common bottom number for 2 and 3 is 6. So ½ becomes 3/6 and ⅓ becomes 2/6. Add the tops: 3 + 2 = 5. The answer is 5/6.
Common questions
How do I enter a negative fraction?
Put a minus sign in front of the top number, or in front of the whole number if it is a mixed number.
What is an improper fraction?
A fraction whose top number is bigger than its bottom number, such as 7/4. It is the same amount as the mixed number 1¾.
Why do fractions need a common denominator to add?
Because you can only add pieces of the same size. Thirds and halves are different sizes, so both are cut into sixths first.