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Fraction Calculator

Add, subtract, multiply and divide fractions, with the result reduced to lowest terms.

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What Fraction Calculator does

Fractions are exact in a way decimals are not: one third is exactly one third, while 0.3333 is an approximation that accumulates error through a calculation.

This works with the fractions themselves and reduces the answer using the greatest common divisor, alongside the decimal equivalent.

  • Addition, subtraction, multiplication and division
  • Automatic reduction to lowest terms
  • Decimal equivalent shown alongside

How to use Fraction Calculator

  1. 1

    Enter the first fraction

    Numerator on top, denominator below.

  2. 2

    Choose the operation

    Add, subtract, multiply or divide.

  3. 3

    Enter the second fraction

    The result appears reduced, with its decimal value.

Example

Addition requires a common denominator

Input

1/2 + 1/3

Output

5/6  (0.8333…)

The denominators are made common at 6, giving 3/6 + 2/6, which is already in lowest terms.

When to use it

Scaling a recipe

Halving or thirding quantities expressed in fractions of a cup without converting to awkward decimals.

Working in imperial measurements

Timber, drill bits and fasteners are sized in fractions of an inch, and adding sixteenths and eighths by hand invites mistakes.

Checking exact arithmetic

Fractions stay exact where decimals round, which matters when a value is used repeatedly in a calculation.

Limits and known behaviour

  • Two fractions per calculation. Longer expressions have to be worked through in steps.
  • Mixed numbers such as 2½ are not accepted directly; convert to an improper fraction first, in this case 5/2.
  • Results are given as improper fractions rather than mixed numbers.
  • A zero denominator is undefined and is rejected.
  • Very large numerators and denominators can exceed the range where integer arithmetic stays exact.

Privacy and data handling

Runs entirely in your browser

  • The calculation runs in this page. Nothing you enter is transmitted or stored.
  • The tool works offline once the page has loaded.

Site-wide data handling, including analytics and advertising, is described in the privacy policy.

Frequently asked questions

How do I enter a mixed number?

Convert it first: multiply the whole part by the denominator and add the numerator. So 2¾ becomes 11/4.

Why is my answer a different fraction from my textbook's?

Check whether it is the same value in lowest terms. 6/8 and 3/4 are equal; this tool always reduces, and some textbooks do not.

How do I divide by a fraction?

Dividing by a fraction is the same as multiplying by its reciprocal, so 1/2 ÷ 1/4 becomes 1/2 × 4/1, which is 2. That is why dividing by a fraction smaller than one makes the answer larger, which reliably feels wrong the first few times.

Why use fractions instead of decimals?

Because one third is exactly one third, while 0.333 is not. In a calculation that reuses the value, the decimal's error compounds and the fraction's does not.