Fraction calculator
Add, subtract, multiply or divide fractions, mixed numbers and whole numbers. The answer updates as you type: simplified, as a mixed number, decimal and percent, with the working written out like a teacher would. For longer problems with brackets, use the expression calculator further down.
Working
- Rewrite mixed numbers as improper fractions (whole × denominator + numerator).
3/2 + 3/4 - Find the least common denominator of 2 and 4: LCD = 4.
- Rewrite each fraction over 4.
3/2 = 6/4, 3/4 = 3/4 - Add the numerators and keep the denominator.
6 + 3 = 9 → 9/4 - 9/4 is already in lowest terms.
- As a mixed number: 9 ÷ 4 = 2 remainder 1.
2 1/4
Quick converters
Why fractions need a common denominator
The denominator names the size of the pieces. You can only add pieces of the same size — so first we re-cut the bars. Step through it:
Step 1 of 3 — Here are 1/2 and 1/3. The pieces are different sizes, so "1 piece plus 1 piece" means nothing yet.
Fraction expression calculator
Several fractions at once, with brackets. Type mixed numbers with a space (2 1/2), and use * or x for ×, / or : for ÷. A fraction like 5/6 always counts as a single number, so 1 ÷ 5/6 means 1 ÷ (5/6). Exact for very large numbers.
Order of operations
Brackets first, then × and ÷ from left to right, then + and − from left to right. Each result is simplified.
- 2/3 × 3/4 = 1/2
- 1/2 + 1/2 = 1
How to use the fraction calculator
- Enter the first fraction. Top box is the numerator, bottom box the denominator. Add a whole number on the left for a mixed number such as 1 1/2.
- Pick an operation: +, −, × or ÷.
- Enter the second fraction. The result, the decimal and percent, and each step appear straight away.
The four rules in one place
Adding and subtracting
Rewrite both fractions over a common denominator, then add or subtract the numerators: 1/2 + 1/3 = 3/6 + 2/6 = 5/6. Full guides: adding fractions and subtracting fractions.
Multiplying
Multiply straight across: 2/3 × 3/4 = 6/12 = 1/2. No common denominator needed. See multiplying fractions for the area picture behind it.
Dividing
Keep the first fraction, change ÷ to ×, flip the second: 3/4 ÷ 1/8 = 3/4 × 8/1 = 6. Why flipping works.
Mixed numbers
Turn them into improper fractions first (2 1/2 = 5/2), calculate, then turn the answer back. The mixed number converter does either direction.
The bars in the explainer above are the same idea teachers use with fraction tiles on the board: the denominator tells you the size of each piece, the numerator how many you have. Once a visual makes an idea click, it sticks, which is exactly what ahaboo aims for with its guided, hands-on lessons on how the world works.
Questions people ask
How do I enter a mixed number like 2 1/2?
Type the whole number (2) in the left box, and the fraction part (1 over 2) in the stacked boxes. Leave the whole-number box empty for a plain fraction. To enter just a whole number, fill only the left box.
How do I enter a negative fraction?
Put the minus sign in the whole-number box: -1 with 1/4 gives −1 1/4, and -0 with 3/4 gives −3/4. The top and bottom boxes take plain whole numbers.
Does the calculator simplify the answer?
Yes. Every answer is reduced to lowest terms by dividing the numerator and denominator by their greatest common factor, and shown as an improper fraction, a mixed number, a decimal and a percent.
What order does it use to add fractions?
It finds the least common denominator (LCD) of the two fractions, rewrites both over the LCD, adds or subtracts the numerators, then simplifies. Using the LCD rather than simply multiplying the denominators keeps the numbers small.
How do you calculate fractions with more than two numbers?
Use the expression calculator on this page: type something like 1/2 + 2/3 × 3/4 or (1 1/2 + 2 1/3) ÷ 5/6. It follows the order of operations (brackets, then × and ÷, then + and −) and shows each step.
How do you add fractions with different denominators?
Rewrite both fractions over a common denominator, ideally the least common denominator, then add the numerators. 1/4 + 1/6 = 3/12 + 2/12 = 5/12.
How do you divide fractions?
Keep the first fraction, change ÷ to ×, and flip the second fraction (use its reciprocal). 3/4 ÷ 1/8 = 3/4 × 8/1 = 6.
Can I share a calculation with a student or teacher?
Yes. Press "Copy link" under the calculator. The link opens this page with the same fractions and operation already filled in.
Is my calculation history stored anywhere?
Only if you press "Save to history", and then only in your own browser (localStorage). Nothing is sent to a server. Use "Clear history" to delete it.