Add, subtract, multiply and divide fractions and mixed numbers.
Adding 1/2 and 1/3 by hand means finding a common denominator first, and this fraction calculator does that step for you while it adds, subtracts, multiplies or divides fractions, mixed numbers and whole numbers. It gives the answer in simplest form, as a mixed number where that helps, and as a decimal. The working is shown step by step, including the common denominator, so it is useful for checking homework as well as for quick sums in the kitchen or workshop.
How to Use the Fraction Calculator
- In First fraction, type a fraction such as 3/4, a mixed number such as 1 1/2 (a whole number, a space, then the fraction), or a whole number such as 2.
- Choose + Add, − Subtract, × Multiply or ÷ Divide.
- Type the Second fraction in the same way.
The result shows the simplified fraction, the mixed number and the decimal, followed by the steps.
Fraction Rules the Calculator Uses
Adding and subtracting. The fractions need the same denominator. The calculator finds the lowest common denominator (LCD), rewrites both fractions over it, then adds or subtracts the numerators.
a/b + c/d = (a × d + c × b) ÷ (b × d), then simplify.
Multiplying. Multiply the numerators together and the denominators together.
a/b × c/d = (a × c) ÷ (b × d)
Dividing. Flip the second fraction and multiply (“keep, change, flip”).
a/b ÷ c/d = a/b × d/c
Mixed numbers are turned into improper fractions first, and the result is simplified by dividing the top and bottom by their greatest common factor.
Fraction Examples
Adding fractions: 1/2 + 1/3. The LCD of 2 and 3 is 6. 1/2 = 3/6 and 1/3 = 2/6, so 3/6 + 2/6 = 5/6 (0.8333…).
Subtracting: 5/6 − 1/4. The LCD is 12. 10/12 − 3/12 = 7/12.
Multiplying mixed numbers: 1 1/2 × 2 2/3. Convert: 3/2 × 8/3 = 24/6 = 4.
Dividing fractions: 3/4 ÷ 2/5. Flip and multiply: 3/4 × 5/2 = 15/8, which is 1 7/8 or 1.875.
Fractions in the Kitchen and Workshop
- Halving a recipe. The recipe needs 3/4 cup of sugar. Enter 3/4 ÷ 2 to get 3/8 cup.
- Scaling up. You need 1 1/2 times a recipe that uses 2/3 cup of milk. Enter 1 1/2 × 2/3 to get 1 cup.
- Cutting timber. You cut 2 5/8 ft from an 8 ft board. Enter 8 − 2 5/8 to get 5 3/8 ft left.
Four Fraction Slip-Ups
- Adding the denominators. 1/2 + 1/3 is not 2/5. Find a common denominator first.
- Forgetting to flip when dividing. Only the second fraction is flipped.
- Multiplying mixed numbers part by part. 1 1/2 × 2 2/3 is not 2 2/6. Convert to improper fractions first.
- Leaving answers unsimplified. 4/8 should be written as 1/2. The calculator always simplifies.
More Fraction Tools
- To reduce a single fraction to lowest terms, use the simplify fractions calculator.
- To convert between mixed numbers and improper fractions, use the mixed number calculator.
- To turn a decimal into a fraction, use the decimal to fraction calculator. For the opposite direction, use the fraction to decimal calculator.
- To find the lowest common denominator of more than two numbers, use the LCM calculator.
Fraction Calculator Questions
How do I enter a mixed number?
Type the whole number, a space, then the fraction: 2 3/4. Do not use a plus sign or a hyphen.
Can I use negative fractions?
Yes. Put a minus sign in front, such as −3/4 or −1 1/2. The calculator keeps track of the sign through each step.
Why is my answer shown three ways?
Different tasks need different forms. Teachers often want the simplest fraction or mixed number, while measuring and spreadsheets usually need the decimal.
Can I add three or more fractions?
Work in steps: add the first two, then add the third fraction to that answer.
How we checked this page: each example was worked by hand using the rules above and matches the calculator’s simplest-form, mixed-number and decimal answers.