Fraction Calculator
Add, subtract, multiply and divide fractions, simplified, with decimal answers.
Enter fractions like 1/2 or whole numbers like 3. A fraction cannot have a denominator of 0, and you cannot divide by zero.
Results are simplified to lowest terms and shown as a fraction, a mixed number, and a decimal. Everything is calculated in your browser — nothing you enter is sent anywhere.
How fraction arithmetic works
| Operation | Rule | Example |
|---|---|---|
| Add | a/b + c/d = (ad + bc) / bd, then simplify | 1/2 + 1/3 = 5/6 |
| Subtract | a/b − c/d = (ad − bc) / bd, then simplify | 3/4 − 1/4 = 1/2 |
| Multiply | a/b × c/d = ac / bd, then simplify | 2/3 × 3/4 = 1/2 |
| Divide | a/b ÷ c/d = a/b × d/c, then simplify | 1/2 ÷ 1/4 = 2 |
Simplifying means dividing the numerator and denominator by their greatest common divisor (GCD). For example, 8/12 simplifies to 2/3 because both 8 and 12 divide by 4.
Fraction calculator — add, subtract, multiply and divide fractions
A fraction calculator adds, subtracts, multiplies, and divides two fractions, then simplifies the answer and shows it as a fraction, a mixed number, and a decimal. Enter fractions like 1/2 or whole numbers like 3, pick an operation, and you get the exact answer — 1/2 + 1/3 = 5/6, not a rounded decimal.
Adding and subtracting need a common denominator: the calculator cross-multiplies (a/b + c/d = (ad + bc) / bd) and then simplifies. Multiplying is simpler — multiply straight across the top and the bottom. Dividing flips the second fraction and multiplies. Every result is reduced to lowest terms using the greatest common divisor, so 8/12 comes out as 2/3 and 2/3 × 3/4 comes out as 1/2.
When the answer is bigger than one, you also get the mixed number — 7/2 is shown as 3 1/2 — and the decimal, 3.5, so you can use whichever form your homework or recipe asks for.
How the fraction calculator works
Common denominators for adding and subtracting; straight across for multiplying and dividing. To add 1/2 + 1/3, both become sixths: 3/6 + 2/6 = 5/6. To multiply, multiply the tops and the bottoms: 2/3 x 3/4 = 6/12 = 1/2. To divide, flip the second fraction and multiply: 1/2 ÷ 1/4 = 1/2 x 4/1 = 2.
Every answer is simplified by dividing top and bottom by their greatest common divisor, and shown as a mixed number and a decimal too: 7/2 is 3 1/2, or 3.5.
Need the average of test scores? Use the average calculator.
How to use the fraction calculator
- Enter the first fraction as a/b (for example 1/2) or as a whole number (for example 3).
- Choose the operation: add, subtract, multiply, or divide.
- Enter the second fraction the same way.
- Press Calculate fraction to see the simplified fraction, the mixed number, and the decimal.
Frequently asked questions
What is 1/2 + 1/3?
5/6. The fractions need a common denominator of 6: 1/2 is 3/6 and 1/3 is 2/6, so 3/6 + 2/6 = 5/6.
How do you simplify a fraction?
Divide the numerator and denominator by their greatest common divisor (GCD). For 8/12, the GCD of 8 and 12 is 4, so 8 ÷ 4 = 2 and 12 ÷ 4 = 3, giving 2/3.
How do you divide fractions?
Flip the second fraction and multiply. 1/2 ÷ 1/4 becomes 1/2 × 4/1 = 4/2 = 2. This calculator does the flip and the simplifying for you.
What is 7/2 as a mixed number?
3 1/2. Two goes into seven three times (3 × 2 = 6) with 1 left over, so 7/2 = 3 1/2, which is 3.5 as a decimal.
Can I enter whole numbers in the fraction calculator?
Yes. Enter a whole number like 3 and it is treated as 3/1, so 3 + 1/2 = 3 1/2. You can mix whole numbers and fractions freely.
Why can I not divide by zero?
Division by zero has no defined answer in mathematics — no number multiplied by zero gives a non-zero result. A fraction with a denominator of 0 is likewise undefined, so the calculator asks for a different value.
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