Fraction Calculator
Add, subtract, multiply, or divide two fractions and get the simplified answer.
Last updated: September 23, 2026
How to add or subtract fractions
To add or subtract two fractions, they need a common denominator first. This tool multiplies the two denominators together to get a guaranteed common denominator, cross-multiplies the numerators to match, adds or subtracts them, and then simplifies the result to its lowest terms using the greatest common divisor so you always get the same final answer you would from finding the least common denominator by hand, just via a different, guaranteed-to-work path.
How to multiply or divide fractions
To multiply two fractions, multiply the numerators together and the denominators together. To divide, multiply the first fraction by the reciprocal (flipped version) of the second.
Where fraction math shows up in real life
Fractions are everywhere outside math class. Scaling a recipe up or down means multiplying every ingredient's fraction by the same factor doubling 3/4 cup of flour means calculating 3/4 2. Woodworking and construction measurements are routinely given in fractions of an inch (like 5/8" or 3 1/4"), and adding cut lengths or figuring out how many pieces fit on a board means adding or dividing those fractions accurately. Even splitting a pizza or a bill fairly among a group is fraction math in disguise. For percentage-based calculations, check our free percentage calculator.
FAQ
Does this show mixed numbers?
Yes if the result is an improper fraction (numerator larger than denominator), it's also shown as a mixed number and a decimal.
Can I use negative numbers?
Yes enter a negative sign in either the numerator or denominator field.
Why is my denominator sometimes bigger than expected before simplifying?
This tool uses the product of your two denominators as a starting common denominator (for advanced calculations, see our free scientific calculator) rather than searching for the smallest possible one, since that's guaranteed to work for any pair of fractions. The final simplification step always reduces it back down to lowest terms, so your answer is identical either way.
Can I enter a whole number instead of a fraction?
Yes enter the whole number as the numerator and 1 as the denominator (for example, 5/1 for the number 5), and it will calculate correctly alongside a true fraction.
What happens if I divide by zero?
Dividing by a fraction equal to zero isn't mathematically defined, so this tool shows an error message instead of a result rather than returning something misleading.