Fractions represent parts of a whole. To add or subtract them, they must share a common denominator.
How to use the Fraction Calculator
- First numerator
- First denominator
- Operation
- Second numerator
- Second denominator
Results update as you type, and every field accepts the units shown in its menu.
How it works
The calculator applies the chosen operation to the two fractions, then simplifies the result to its lowest terms.
Inputs explained
| Field | What to enter |
|---|---|
| First numerator | A number |
| First denominator | A number |
| Operation | Choose one: + add, − subtract, × multiply, ÷ divide |
| Second numerator | A number |
| Second denominator | A number |
What each result means
- Simplified numerator = [Numerator] ÷ [Common factor] × sign([Denominator])
- Simplified denominator = abs([Denominator] ÷ [Common factor])
- Result = [Numerator] ÷ [Denominator]
- Decimal = [Numerator] ÷ [Denominator]
Formula
a/b + c/d = (ad + bc) ÷ bda/b × c/d = ac ÷ bda/b ÷ c/d = ad ÷ bcWorked example
Inputs — First numerator: 3; First denominator: 4; Operation: + add; Second numerator: 2; Second denominator: 3.
Results — Simplified numerator = 17; Simplified denominator = 12; Result = 1 5/12; Decimal = 1.41666667.
Key terms
- Denominator
- The bottom number of a fraction.
- Mixed number
- A whole number plus a proper fraction.
Frequently asked questions
How do I add fractions with different denominators?
Convert both to a common denominator, add the numerators and simplify.
Why flip the second fraction when dividing?
Dividing by a fraction is the same as multiplying by its reciprocal.
What formula does the Fraction Calculator use?
a/b + c/d = (ad + bc) ÷ bd.