Fraction Calculator
Add two fractions and reduce the result.
Inputs
Allowed range: -1000000 to 1000000
Allowed range: -1000000 to 1000000
Allowed range: -1000000 to 1000000
Allowed range: -1000000 to 1000000
Results
How it works
Convert to a common denominator, add numerators, then reduce by the greatest common divisor.
Complete guide
To add two fractions you first need a common denominator. Multiply the denominators together to get one (the cross-multiply method), add the rewritten numerators, then reduce the result by dividing both top and bottom by their greatest common divisor.
Example: 1/2 + 1/3. Common denominator is 6. Rewrite as 3/6 + 2/6 = 5/6. The greatest common divisor of 5 and 6 is 1, so 5/6 is already in simplest form.
This calculator handles the bookkeeping automatically and also gives you the decimal equivalent — useful when you need to plug the result into another calculation that expects a number, not a fraction.
Frequently asked questions
- Can I enter negative fractions?
- Yes. Use a negative numerator (e.g. -1/2). Avoid putting the minus sign on the denominator.
- What if I divide by zero?
- A denominator of zero is mathematically undefined. The calculator will return a non-finite value — change it to a non-zero number.
- How do I subtract fractions?
- Enter the second numerator as negative. For example, 1/2 − 1/3 = 1/2 + (-1)/3.
- Why is the decimal sometimes a long number?
- Many fractions can't be expressed exactly in decimal form (1/3 = 0.3333...). The calculator rounds to four decimal places.