How this calculator works
To add or subtract, the fractions need a common denominator: a/b ± c/d = (a×d ± c×b) / (b×d).
To multiply, multiply the tops and the bottoms: a/b × c/d = (a×c) / (b×d).
To divide, multiply by the reciprocal of the second fraction: a/b ÷ c/d = a/b × d/c.
The result is simplified by dividing top and bottom by their greatest common factor. Mixed numbers are converted first: 1 1/2 becomes 3/2.
Worked example
3/4 + 2/3
- Common denominator: 4 × 3 = 12.
- (3 × 3 + 2 × 4) / 12 = 17/12.
- As a mixed number: 1 5/12. As a decimal: 1.416667.
Questions people ask
How do I simplify a fraction?
Divide the numerator and denominator by their greatest common factor. 18/24 ÷ 6 = 3/4.
How do I convert a decimal to a fraction?
Write it over a power of ten and simplify: 0.375 = 375/1000 = 3/8.
How do I compare two fractions?
Cross-multiply: for a/b and c/d, compare a × d with c × b. For 3/4 and 2/3, 9 is more than 8, so 3/4 is larger.
Can I enter negative fractions?
Yes, for example −3/4 or −1 1/2.
Last reviewed October 2, 2026