Everyday math
Fraction calculator
Enter two fractions as whole-number numerators and denominators, then pick an operation. The answer is reduced to lowest terms.
What this means
- 3/4 + 5/6 = 19/12, which is 1.58333333 as a decimal.
- The answer is divided by the greatest common divisor of its top and bottom, so it is in lowest terms.
What if
About this calculator
What this calculator does
It combines two fractions with the operation you pick and reduces the answer to lowest terms. It also shows a mixed number and a decimal.
How it is calculated
a/b + c/d = (a*d + c*b) / (b*d)
a/b - c/d = (a*d - c*b) / (b*d)
a/b * c/d = (a*c) / (b*d)
a/b / c/d = (a*d) / (b*c)
The result is then divided top and bottom by their greatest common divisor.
How to read the result
The answer is an improper fraction when the top is larger than the bottom. The mixed number shows the same value as a whole number plus a fraction.
Sources and method
Standard arithmetic with no outside data. The formula is shown under How it is calculated, and unit tests check worked examples, including edge cases.
This page uses arithmetic only, with no outside data.
Questions
How do I enter a mixed number like 1 1/2?
Convert it first: 1 1/2 is 3/2. Multiply the whole number by the denominator and add the numerator.
Can I use negative fractions?
Yes. Put the minus sign on the numerator.
What does simplified mean?
The top and bottom share no common factor other than 1.
Why can't the denominator be 0?
Division by zero is undefined.