Fraction Calculator
Add, subtract, multiply or divide two fractions. Enter each numerator and denominator, pick the operation, and the answer comes back in lowest terms, as a mixed number and as a decimal. The arithmetic is done with whole numbers, so there is no rounding error.
- As a mixed number
- 5/6
- As a decimal
- 0.833333
Saved setups
Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.
Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
How to use it
- Enter the numerator and denominator of the first fraction.
- Choose add, subtract, multiply or divide.
- Enter the second fraction.
- Read the simplified answer, its mixed-number form and its decimal value.
Worked examples
1/2 + 1/3
- Answer (simplified)
- 5/6
- As a mixed number
- 5/6
- As a decimal
- 0.833333
3/4 ÷ 2/5
- Answer (simplified)
- 15/8
- As a mixed number
- 1 7/8
- As a decimal
- 1.875
3/4 − 1/6
- Answer (simplified)
- 7/12
- As a decimal
- 0.583333
Adding and subtracting
Fractions can only be added or subtracted once they share a denominator. For 1/2 + 1/3, rewrite both over 6: 3/6 + 2/6 = 5/6. The cross-multiplying formula above does the same thing in one step and the result is then reduced.
Multiplying and dividing
To multiply, multiply the tops together and the bottoms together — no common denominator needed. To divide, keep the first fraction, flip the second, and multiply: 3/4 ÷ 2/5 = 3/4 × 5/2 = 15/8, or 1 7/8.
For a negative fraction, put the minus sign on the numerator. For whole numbers, use a denominator of 1.
Questions people ask
What is 1/2 + 1/3?
5/6. Over a common denominator of 6 it is 3/6 + 2/6.
What is 3/4 divided by 2/5?
15/8, which is 1 7/8 or 1.875. Flip the second fraction and multiply: 3/4 × 5/2.
What is 2/3 times 9/10?
3/5. Multiplying gives 18/30, and dividing the top and bottom by 6 gives 3/5.