Fraction Calculator
Free to use. Runs in your browser: your files and text are not uploaded.
Type two fractions and choose an operation. The answer is given in its simplest form, as a mixed number, and as a decimal.
How to use it
- Type the top number (numerator) and bottom number (denominator) of the first fraction.
- Choose +, −, × or ÷.
- Type the second fraction. The answer updates as you type.
For a whole number, use 1 as the bottom number: 5 is 5/1.
The rules
| Operation | Rule | Example |
|---|---|---|
| Add | (a×d + c×b) / (b×d) | 1/2 + 1/3 = 5/6 |
| Subtract | (a×d − c×b) / (b×d) | 3/4 − 1/6 = 7/12 |
| Multiply | (a×c) / (b×d) | 2/3 × 3/5 = 2/5 |
| Divide | (a×d) / (b×c) | 3/4 ÷ 3/8 = 2 |
Here the first fraction is a/b and the second is c/d.
Simplifying
A fraction is in its simplest form when no number other than 1 divides both the top and the bottom. The tool finds the greatest common divisor of the two and divides both by it.
Example: 3/4 − 1/6 first gives (3×6 − 1×4)/(4×6) = 14/24. The greatest common divisor of 14 and 24 is 2, so the answer is 7/12.
Mixed numbers
A fraction with a top larger than its bottom can be written as a whole number and a fraction. 7/4 is 1 whole and 3/4 left over, written 1 3/4. The tool shows this form whenever the answer is larger than 1.
Limits
- Tops and bottoms must be whole numbers. Negative numbers are allowed.
- A bottom number of zero is not allowed, and neither is dividing by a fraction equal to zero.
- The decimal is rounded to 6 places. 1/3 shows as 0.333333.
Frequently asked questions
How do I add fractions with different denominators?
Give them the same bottom number first. For 1/2 + 1/3, multiply each fraction to get sixths: 3/6 + 2/6 = 5/6.
How do I divide fractions?
Turn the second fraction upside down and multiply. 3/4 ÷ 3/8 becomes 3/4 × 8/3 = 24/12 = 2.
How do I enter a mixed number such as 1 3/4?
Convert it to a single fraction first: multiply the whole number by the bottom and add the top. 1 3/4 is (1 × 4 + 3)/4 = 7/4.