Quick answer: A fraction represents part of a whole as numerator over denominator. Simplify by dividing both by their greatest common divisor. To add or subtract, use a common denominator; to multiply, multiply straight across; to divide, multiply by the reciprocal. Mixed numbers combine a whole number with a fraction, like 2 and 1/2.
Last reviewed: September 2026
Key facts
- Adds, subtracts, multiplies and divides fractions, simplifying every answer automatically.
- Enter fractions as a/b (e.g. 3/4) or whole numbers (e.g. 5).
- Every result is reduced with the greatest common divisor — 6/20 becomes 3/10.
- Shows the decimal equivalent alongside the exact fraction.
Fractions trip up even confident maths students — different denominators, mixed operations, simplifying at the end. This free fraction calculator adds, subtracts, multiplies and divides fractions for you, reducing each answer to simplest form and showing the decimal too.
Type each fraction as a/b (like 3/4), pick the operation, and get the exact simplified result instantly.
How to use
- Type the first fraction as a/b (e.g. 1/2) or a whole number.
- Choose +, −, × or ÷.
- Type the second fraction.
- Read the simplified answer and its decimal equivalent.
Fraction arithmetic rules
| Term | Meaning |
|---|---|
| Addition / subtraction | Give both fractions the common denominator bd, then add or subtract the tops. |
| Multiplication | Multiply tops together and bottoms together: a/b × c/d = ac/bd. |
| Division | Flip the second fraction and multiply (invert and multiply). |
| Simplifying | Divide top and bottom by their greatest common divisor. |
Dividing by a fraction is the same as multiplying by its reciprocal — the single trick that makes fraction division easy.
Worked examples
Adding and subtracting
1/2 + 1/3: common denominator 6 → 3/6 + 2/6 = 5/6 (≈ 0.833).
3/4 − 1/2: 3/4 − 2/4 = 1/4 (≈ 0.25).
Multiplying and dividing
2/3 × 3/4 = 6/12 = 1/2 (≈ 0.5) — simplified automatically.
5/6 ÷ 2/3: flip to 5/6 × 3/2 = 15/12 = 5/4 (≈ 1.25).
Common fraction ↔ decimal pairs
| Fraction | Decimal | Useful for |
|---|---|---|
| 1/2 | 0.5 | Halves |
| 1/3 | 0.333… | Thirds |
| 1/4 | 0.25 | Quarters |
| 1/5 | 0.2 | Fifths |
| 1/8 | 0.125 | Eighths |
| 3/4 | 0.75 | Three quarters |
| 2/3 | 0.667… | Two thirds |
Frequently asked questions
How do I enter a fraction?
Type it as a/b, for example 3/4. Whole numbers work too — just type 5.
Why must denominators match for addition?
You can only add like-sized pieces. 1/2 + 1/3 means halves plus thirds; converting to 3/6 + 2/6 gives sixths you can add.
How do you divide fractions?
Invert (flip) the second fraction and multiply: 5/6 ÷ 2/3 = 5/6 × 3/2 = 5/4.
What does “simplified” mean?
Dividing top and bottom by their greatest common divisor until no further reduction is possible — 6/20 becomes 3/10.
Can it handle negative fractions?
Yes — type -3/4 and the sign is carried through the calculation correctly.
Sources
- Khan Academy — Fraction arithmetic courses
- Maths is Fun — Fractions with visual examples
What is an improper fraction?
One where the top exceeds the bottom, like 5/4. It equals 1¼ as a mixed number.
Key takeaways
- Add/subtract with a common denominator; multiply straight across; flip-and-multiply to divide.
- Answers are auto-simplified using the greatest common divisor.
- Every result includes its decimal equivalent for checking.
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