Fraction Calculator
Add, subtract, multiply, and divide fractions, with results simplified to lowest terms and shown as mixed numbers.
How to use this calculator
- Enter the numerator and denominator of both fractions.
- Choose the operation (add, subtract, multiply, divide).
- The answer is simplified automatically and shown as a mixed number and a decimal.
The formula
a/b + c/d = (a×d + c×b) ÷ (b×d)- a, c
- Numerators (the top numbers)
- b, d
- Denominators (the bottom numbers, never zero)
How it works
To add or subtract, the fractions need a common denominator: multiply each fraction's top and bottom by the other's denominator, then combine the numerators.
Multiplication is straight across (tops × tops, bottoms × bottoms). Division flips the second fraction and multiplies. Every result is then reduced by dividing top and bottom by their greatest common divisor.
Worked example
Add 1/2 and 3/4.
- 1Common denominator: 1/2 = 2/4
- 22/4 + 3/4 = 5/4
- 35/4 is already in lowest terms
5/4, which is 1 1/4 or 1.25.
When this calculator is useful
- Recipes and cooking measurements
- Carpentry and DIY measurements
- Homework checking
- Comparing proportions exactly (no decimal rounding)
Frequently asked questions
What does 'simplify' mean?
Dividing the numerator and denominator by their greatest common divisor so the fraction uses the smallest possible whole numbers — 4/8 simplifies to 1/2.
What is a mixed number?
A whole number plus a proper fraction, like 1 3/4, used for values greater than 1.