Fraction calculator
To add two fractions, put them over a common denominator: 1/2 + 1/3 = 3/6 + 2/6 = 5/6. Enter two fractions and an operation; the answer is simplified for you.
- Checked on thousands of cases
- Updated November 1, 2026
Addition
Result
≈ 0.8333333333
Quick challenge
Streak 0Best 0
Test yourself: every answer is computed by the tool, and the wrong choices are the most common traps.
How it works
Formula: a/b + c/d = (a×d + c×b) / (b×d)
To add or subtract, multiply each numerator by the other fraction's denominator and work over the product of the denominators: a/b + c/d = (a×d + c×b) ÷ (b×d). To multiply, multiply the numerators together and the denominators together. To divide, multiply by the reciprocal of the second fraction. The result is then divided by the greatest common divisor of its numerator and denominator to reach its lowest terms.
Worked examples
1/2 + 1/3
Same denominator: 3/6 + 2/6 = 5/6.
3/4 × 2/3
Tops together, bottoms together: 6/12 = 1/2.
2/3 ÷ 1/6
Multiply by the reciprocal: 2/3 × 6/1 = 4.
Common mistakes
Adding tops and bottoms: 1/2 + 1/3 = 2/5.
Find a common denominator first: 5/6.
Dividing without flipping the second fraction: 2/3 × 1/6 = 1/9.
Dividing by 1/6 means multiplying by 6: 4.
Leaving 6/8 as it is.
Simplify by the greatest common divisor: 3/4.
Common fractions as decimals and percentages
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/2 | 0.5 | 50% |
| 1/3 | 0.333333 | 33.33% |
| 2/3 | 0.666667 | 66.67% |
| 1/4 | 0.25 | 25% |
| 3/4 | 0.75 | 75% |
| 1/5 | 0.2 | 20% |
| 2/5 | 0.4 | 40% |
| 1/6 | 0.166667 | 16.67% |
| 1/8 | 0.125 | 12.5% |
| 3/8 | 0.375 | 37.5% |
| 5/8 | 0.625 | 62.5% |
| 7/8 | 0.875 | 87.5% |
| 1/10 | 0.1 | 10% |
| 1/16 | 0.0625 | 6.25% |
Frequently asked questions
How do I simplify a fraction?
Divide the numerator and the denominator by their greatest common divisor. For 18/24, the greatest common divisor is 6, so 18/24 = 3/4.
How do I divide two fractions?
Multiply the first fraction by the second one flipped upside down: 2/3 ÷ 4/5 = 2/3 × 5/4 = 10/12 = 5/6.
What is a mixed number?
A whole number plus a proper fraction. 7/3 is 2 and 1/3, written 2 1/3, because 7 = 2 × 3 + 1.
How do I turn a fraction into a decimal?
Divide the numerator by the denominator: 3/8 = 3 ÷ 8 = 0.375. Some fractions, like 1/3 = 0.333…, repeat forever.