Fraction calculator
Add, subtract, multiply and divide fractions, with the result already simplified.
How the calculation works
Each operation with fractions has its own rule. The denominator (bottom) says how many parts the whole was split into; the numerator (top), how many you have.
Addition and subtraction
You can only add fractions with the same denominator. When they differ, match them via the LCM (or cross-multiply), then add the numerators:
1/2 + 1/3 = 3/6 + 2/6 = 5/6
Multiplication
The simplest: numerator times numerator, denominator times denominator. No matching needed.
2/3 × 4/5 = 8/15
Division
Dividing fractions becomes multiplying by the reciprocal (flip the second and multiply):
2/3 ÷ 4/5 = 2/3 × 5/4 = 10/12 = 5/6
Simplifying
Finally, divide numerator and denominator by their GCD. E.g. 10/12 has GCD 2 → 5/6.
Examples
- 3/4 + 1/6: LCM 12 → 9/12 + 2/12 = 11/12.
- 5/6 ÷ 2/3 = 5/6 × 3/2 = 15/12 = 5/4.
Frequently asked questions
How to simplify a fraction?
Divide numerator and denominator by their greatest common divisor (GCD). Repeat until the only common divisor is 1.
Why do I need a common denominator to add?
Because you can only add parts of the same size. 1/2 and 1/3 are different-sized slices; a common denominator puts them in the same unit.
How to convert a fraction to a decimal?
Divide the numerator by the denominator. 3/4 = 3 ÷ 4 = 0.75. We have a dedicated calculator for this.
What is an improper fraction?
One whose numerator exceeds the denominator (e.g. 5/4). It is greater than 1 and can become a mixed number: 5/4 = 1 1/4.
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Updated on June 17, 2026 · by Rafael Rossi · Methodology & sources