Fraction Calculator guide
Fraction Calculator: Add, Subtract, Multiply and Divide Fractions
Use our fraction calculator to add, subtract, multiply, divide and simplify fractions and mixed numbers, with the working shown.
By the AllCalculator editorial teamUpdated 16 October 20261 min read
Fractions come up everywhere, from recipes to homework. Our Fraction Calculator does the working for you and gives the answer in its simplest form.
How to use the calculator (Fraction Calculator)
- Choose what to do: add, subtract, multiply, divide, simplify or convert a decimal.
- Type your fractions, like 3/4, mixed numbers like 1 1/2, or whole numbers.
You'll see the answer in its simplest form, as a mixed number, a decimal and a percentage.
How it works
- Adding and subtracting: find a common denominator (the lowest common multiple of the bottom numbers), rewrite both fractions, then add or subtract the tops.
- Multiplying: multiply the tops together and the bottoms together.
- Dividing: flip the second fraction and multiply.
- Simplifying: divide the top and bottom by their greatest common factor.
A worked example
With the calculator's default settings, 1/2 + 1/3:
- The common denominator is 6
- 1/2 = 3/6 and 1/3 = 2/6
- 3/6 + 2/6 = 5/6, or about 0.833
Frequently asked questions
What's a mixed number?
A whole number and a fraction together, like 1 1/2. It's the same as the improper fraction 3/2.
How do I turn a decimal into a fraction?
Choose "Convert a decimal to a fraction". For example, 0.375 = 375/1000 = 3/8.
Can I use negative fractions?
Yes. Type a minus sign, like -3/4.
To find a common denominator yourself, use our Least Common Multiple Calculator. To simplify, see our Greatest Common Factor Calculator.
Sources and further reading
- GOV.UK: National curriculum in England – mathematicsgov.uk
- Wolfram MathWorld: Fractionmathworld.wolfram.com
Links open official and independent websites in a new tab.
This guide is general information to help you understand your options. It isn't financial, tax, legal or building advice and doesn't take your personal circumstances into account. Figures were checked when the guide was last updated and can change, so confirm anything important with GOV.UK, HMRC, a regulated adviser or a qualified tradesperson.