Fraction Calculator
Add, subtract, multiply or divide fractions, mixed numbers, integers and decimals. Every result is reduced automatically and displayed as a fraction, mixed number and decimal.
Fraction formulas
For fractions a/b and c/d:
- Add: (a × d + c × b) / (b × d)
- Subtract: (a × d − c × b) / (b × d)
- Multiply: (a × c) / (b × d)
- Divide: (a × d) / (b × c), where c is not zero
The result is reduced by dividing its numerator and denominator by their greatest common divisor. A terminating decimal is converted exactly by using a power of ten as its denominator before reduction; for example, 0.625 = 625/1000 = 5/8.
Checked examples
| Calculation | Reduced result | Mixed/decimal form |
|---|---|---|
| 1/2 + 1/3 | 5/6 | 0.833333333333… |
| 3/4 − 1/2 | 1/4 | 0.25 |
| 2/3 × 9/10 | 3/5 | 0.6 |
| 5/6 ÷ 10/9 | 3/4 | 0.75 |
| 1 1/2 + 3/4 | 9/4 | 2 1/4 |
| Convert 0.625 | 5/8 | 0.625 |
How to use the Fraction Calculator
- Select addition, subtraction, multiplication, division or simplification.
- Enter fractions, mixed numbers, integers or terminating decimals.
- For simplification or decimal conversion, only the first value is used.
- Select Calculate fraction to see the exact reduced fraction, mixed number and decimal.
Limits and interpretation
- Denominators cannot be zero, and division by a zero-valued second number is undefined.
- Mixed-number fractional parts must be proper: use 2 1/3 rather than 1 4/3.
- Decimal input must use a point and cannot use scientific notation or thousands separators.
- Up to 30 digits are accepted per input. Exact fraction arithmetic uses integers; the displayed decimal is rounded to at most 12 places.
- Repeating decimals cannot be entered with an ellipsis. Enter their exact fraction, such as 1/3.
Frequently asked questions
Does the calculator simplify fractions automatically?
Yes. Every fraction result is divided by the greatest common divisor of its numerator and denominator.
Can I enter mixed numbers?
Yes. Put one space between the whole number and fraction, as in 2 3/5 or -2 3/5.
Can I convert a decimal to a fraction?
Yes. Choose “Simplify or convert one value” and enter a terminating decimal such as 0.375.
Why does the decimal sometimes end with an ellipsis?
Some fractions produce repeating decimals. The fraction remains exact while the decimal display is rounded.
Related calculators
Use the Ratio Calculator to simplify and scale proportions, the Percentage Calculator for percentage change, or the Inches to Fractions Calculator for measurement-specific rounding.