Fraction Calculator
Add, subtract, multiply and divide fractions, simplify them, and convert to and from decimals.
Formula
a/b + c/d = (ad + cb) / bd, then divide by the greatest common divisor
Tips
- To add or subtract, the denominators must match — multiplying them together always works, though it may not give the smallest common denominator.
- Dividing by a fraction is the same as multiplying by its reciprocal: ÷ 2/3 is × 3/2.
- A fraction is fully simplified when the numerator and denominator share no common factor other than 1.
Frequently asked questions
Why is my answer not the smallest denominator?
It should be — the result is divided by the greatest common divisor. If it looks large, check the inputs: 1/3 + 1/7 genuinely needs 21 as the denominator.