Fraction Calculator

How to add and subtract fractions

a/b + c/d = (a × d + c × b) ÷ (b × d)

Fractions need a common denominator before they can be added or subtracted. Multiplying the two denominators always gives one, and the result is then simplified by dividing the top and bottom by their greatest common factor.

Worked example

1/2 + 3/4 = (1 × 4 + 3 × 2) ÷ (2 × 4) = 10/8. Dividing both by 2 gives 5/4, which is the mixed number 1 1/4 or the decimal 1.25.

Multiplying and dividing fractions

a/b × c/d = (a × c) ÷ (b × d) a/b ÷ c/d = a/b × d/c

To multiply, multiply straight across. To divide, flip the second fraction (take its reciprocal) and multiply. For example, 2/3 ÷ 4/5 = 2/3 × 5/4 = 10/12 = 5/6.

Mixed numbers

Enter a mixed number such as 2 1/3 as whole number 2, numerator 1 and denominator 3. The calculator converts it to the improper fraction 7/3 before working it out.

Frequently asked questions

How do I simplify a fraction?

Divide the numerator and denominator by their greatest common factor. 18/24 simplifies to 3/4 because both divide by 6.

How do I convert a fraction to a decimal?

Divide the numerator by the denominator. 3/8 = 3 ÷ 8 = 0.375.

How do I turn an improper fraction into a mixed number?

Divide the numerator by the denominator. The quotient is the whole number and the remainder goes over the original denominator: 11/4 = 2 3/4.

Can I enter negative fractions?

Yes. Put a minus sign on the whole number or the numerator.