Fraction Calculator
Add, subtract, multiply and divide fractions, with results simplified automatically.
How to Use
- Choose which operation you need from the options above the form.
- Enter each fraction as a numerator (top number) and denominator (bottom number).
- The result updates instantly, already simplified to lowest terms.
- Use Copy Result to copy the answer to your clipboard.
Formula
- Add
- a/b + c/d = (a×d + c×b) / (b×d)
- Subtract
- a/b − c/d = (a×d − c×b) / (b×d)
- Multiply
- a/b × c/d = (a×c) / (b×d)
- Divide
- a/b ÷ c/d = (a×d) / (b×c)
Worked Example
1/2 plus 1/3.
- Cross-multiply to get a common denominator: (1×3 + 1×2) / (2×3) = 5/6.
- 5/6 is already in lowest terms (the greatest common factor of 5 and 6 is 1).
- As a decimal: 5 ÷ 6 ≈ 0.833333.
Result: 5/6 (0.833333)
About This Tool
What this tool does
This calculator adds, subtracts, multiplies or divides two fractions, working in exact whole-number arithmetic and always simplifying the result to lowest terms.
When to use it
Use it for schoolwork, recipe scaling, woodworking or any other situation where you need exact fraction arithmetic instead of a rounded decimal.
What the result means
The result shows the simplified fraction first. When the fraction is 1 or greater, it's shown as a mixed number (a whole number plus a proper fraction), e.g. "1 3/4" instead of "7/4". A decimal equivalent is shown in parentheses whenever it adds information the fraction alone doesn't — it's omitted when the result is already a whole number.
Assumptions & limitations
Numerators and denominators must be whole numbers — this tool works with traditional integer fractions, not decimal numerators. A denominator of zero is rejected as undefined, and dividing by a zero-valued fraction (e.g. 0/5) is likewise rejected as a division by zero. A negative fraction can be entered either as a negative numerator or a negative denominator — both are treated as the same value.