Adding Fractions Calculator

Adding fractions at a glance#

An adding fractions calculator adds two or more fractions and returns the answer in lowest terms. To add fractions, give them a common denominator, add the numerators, keep the denominator, then simplify. For example, 1/4 + 1/3 becomes 3/12 + 4/12, which is 7/12.

When the denominators already match, add the numerators and leave the denominator alone: 1/5 + 2/5 = 3/5. When they differ, find the least common denominator first, rewrite each fraction over it, and then add.

Enter your fractions in the calculator above for the exact sum, reduced to lowest terms and shown as a mixed number when the result is greater than one. It also subtracts fractions the same way, so swap the plus for a minus when you need a difference.

How adding fractions works#

Fractions only add directly when their denominators match. Same denominator: add the numerators and keep the denominator. So 1/4 + 2/4 + 3/4 = 6/4, which reduces to 3/2, or 1 1/2 as a mixed number. Different denominators: rewrite both over a common denominator first, then add.

Adding fractions with unlike denominators#

Find the least common denominator (LCD), the smallest number both denominators divide into, then convert each fraction to it. For 1/2 + 1/3 the LCD is 6, so 1/2 becomes 3/6 and 1/3 becomes 2/6, and 3/6 + 2/6 = 5/6. Multiplying the denominators always gives a usable common denominator, but the LCD keeps the numbers smaller.

Simplifying the answer#

Reduce the result by dividing the numerator and denominator by their greatest common factor. 6/4 has a common factor of 2, so it becomes 3/2. When the numerator is larger than the denominator, the calculator also shows the mixed number: 3/2 is 1 1/2. Negative fractions follow the same steps; the sign rides with the numerator.

Subtracting fractions#

Subtraction uses the same common-denominator step, then you subtract the numerators instead of adding. For 3/4 minus 1/6, the LCD is 12: 9/12 minus 2/12 is 7/12. Enter a minus sign between the fractions in the calculator to get a difference.

Frequently asked questions#

How do you add fractions with different denominators?#

Convert both fractions to a common denominator, add the numerators, keep the denominator, then simplify. For 1/2 + 1/3, use 6: 3/6 + 2/6 = 5/6.

Can this calculator subtract fractions too?#

Yes. Choose a minus sign between the fractions and it subtracts using the same common-denominator method, returning the answer in lowest terms.

How many fractions can I add at once?#

You can add several fractions in one calculation. The calculator finds a common denominator across all of them, adds the numerators, and reduces the total.

How do I add a whole number to a fraction?#

Write the whole number as a fraction over 1, then add. To compute 2 + 1/4, use 2/1, give both a denominator of 4 (8/4 + 1/4), and you get 9/4, or 2 1/4.

Why does the answer show as a mixed number?#

When the sum is greater than 1, the numerator exceeds the denominator. The calculator shows both the improper fraction and the mixed number, so 7/4 also appears as 1 3/4.