Introduction
This adding fractions calculator adds and subtracts fractions for you and shows every step. Type an expression like 1/2 + 3/4, press Calculate, and you get the answer as a simplified fraction, a mixed number, a decimal, and a percent.
You can use plain fractions (3/8), mixed numbers (2 1/2), whole numbers (5), and even decimals (2.5). Add up to nine values in one line, and mix plus and minus signs however you need.
The step-by-step solution shows how to find the least common denominator, rewrite each fraction, add the numerators, and reduce the answer with the greatest common factor. A bar chart also compares each term to the total, so you can see the sizes at a glance.
It helps with homework, cooking measurements, and shop or building math. Turn off auto-simplify if your teacher wants the unreduced answer, and use the on-screen keypad if typing is easier that way.
How to use our Adding Fractions Calculator
Type a fraction problem into the box, and the calculator gives you the answer as a simplified fraction, a mixed number, a decimal, and a percent, plus step-by-step work and a chart.
Fraction expression: Type your fractions here. Use / for the fraction bar, like 1/2. Put a space between a whole number and a fraction for mixed numbers, like 3 1/4. Use + to add and - to subtract. You can enter up to 9 values, and whole numbers or decimals work too.
Try an example: Click one of the sample buttons to fill the box and solve it right away. This is a fast way to see how adding fractions works.
Auto-simplify result to lowest terms: Leave this switch on to reduce the answer using the greatest common factor. Turn it off if you want to keep the fraction over the least common denominator.
Show Keypad: Click this to open a button pad with numbers, the slash, plus, minus, space, and backspace. It helps you type fractions on a phone or tablet.
Calculate: Press this to solve. The result box shows the fraction and mixed number, and the steps below show the LCD, the converted fractions, and the final answer.
Clear: Press this to empty the box and start a new problem.
How to Add Fractions
A fraction has two parts. The top number is the numerator. It tells how many parts you have. The bottom number is the denominator. It tells how many equal parts make one whole. In 3/4, you have 3 of 4 equal parts.
To add fractions, the bottom numbers must match. When the denominators are the same, just add the top numbers and keep the bottom number the same:
1/5 + 2/5 = 3/5
Adding Fractions With Different Denominators
When the bottom numbers are different, you need a common denominator first. The easiest one to use is the least common denominator (LCD). That is the smallest number both denominators divide into evenly, and you can look it up for any set of numbers with the LCM calculator.
- Find the LCD of the denominators.
- Multiply the top and bottom of each fraction by the same number so each bottom equals the LCD.
- Add (or subtract) the top numbers. Keep the LCD on the bottom.
- Simplify the answer.
Example: 1/3 + 1/4. The LCD of 3 and 4 is 12. So 1/3 becomes 4/12, and 1/4 becomes 3/12. Now add: 4/12 + 3/12 = 7/12.
Simplifying the Answer
To put a fraction in lowest terms, divide the top and bottom by their greatest common factor (GCF). For example, 6/8 has a GCF of 2, so 6/8 = 3/4. The value stays the same, but the numbers are smaller and easier to read.
Mixed Numbers and Improper Fractions
A mixed number has a whole number and a fraction, like 2 1/2. An improper fraction has a top number bigger than the bottom, like 5/2. They can mean the same amount.
- Mixed to improper: multiply the whole number by the denominator, then add the numerator. So 2 1/2 = (2 × 2 + 1)/2 = 5/2.
- Improper to mixed: divide the top by the bottom. The answer is the whole number, and the remainder becomes the new top. So 7/3 = 2 1/3.
Always change mixed numbers into improper fractions before you add them. Whole numbers work too. Just write them over 1, like 5 = 5/1.
Subtracting Fractions
Subtracting works the same way. Find the LCD, change each fraction, then subtract the top numbers instead of adding them. If the answer is negative, the fraction you took away was bigger.
Why This Matters
Adding fractions shows up in cooking, building, money, music, and time. If a recipe needs 1/2 cup of milk and 1/3 cup of cream, you need 5/6 cup of liquid in total. Knowing how to combine fractions helps you measure and plan without guessing. Fractions also feed into related skills like converting a part of a whole into a percentage.