Fraction Calculator
Fractions the way they look in your homework: pick an operation and get a simplified answer, the mixed number and the decimal — instantly.
Spotted a mistake or have an idea? — errors get fixed and credited publicly.
Last reviewed: July 20, 2026 · Formulas verified by automated tests before every release.
The four rules, in one place
- Add / subtract: common denominator first — a/b ± c/d = (ad ± cb) / bd, then simplify.
- Multiply: straight across — a/b × c/d = ac/bd.
- Divide: flip and multiply — a/b ÷ c/d = ad/bc.
- Simplify: divide top and bottom by their GCD until nothing divides both.
Why answers get marked wrong
The classic mistake isn't the arithmetic — it's stopping too early. 10/8 is technically correct but most teachers expect 5/4 (or 1 1/4). This calculator always reduces to lowest terms and shows the mixed number, so the answer is in the form the grader wants.
Frequently asked questions
How do you add fractions with different denominators?
Bring them to a common denominator: multiply each numerator by the other fraction's denominator, add the results, and put them over the product of the denominators. Then simplify: 1/2 + 3/4 = (1×4 + 3×2) / (2×4) = 10/8 = 5/4.
How does the calculator simplify fractions?
It divides the numerator and denominator by their greatest common divisor (GCD). 10/8 → GCD is 2 → 5/4. The result is always shown fully reduced.
What is a mixed number?
A whole number plus a proper fraction: 5/4 = 1 1/4. The calculator shows the mixed form automatically whenever the result is an improper fraction.
How do you divide fractions?
Multiply by the reciprocal — flip the second fraction and multiply: (1/2) ÷ (3/4) = (1/2) × (4/3) = 4/6 = 2/3.