Fraction Calculator

Add, subtract, multiply and divide fractions and see every step: the common denominator, the GCD used to simplify, the mixed number and the decimal value. Free and instant — all math runs in your browser.

Whole numbers and negatives are fine — use 1 as the denominator for a whole number (e.g. 5/1).

How to use the fraction calculator

  1. Enter both fractions. Type the numerator (top) and denominator (bottom) of each fraction. Negative fractions like -3/4 and whole numbers like 5/1 work too.
  2. Choose the operation. Pick + to add, − to subtract, × to multiply or ÷ to divide. The answer updates instantly.
  3. Read the steps and copy. The step-by-step box shows the common denominator, the multiplication, and the GCD used to simplify — great for checking homework.

About this tool

This free fraction calculator performs all four basic operations on fractions and always returns the answer in lowest terms, together with the equivalent mixed number and decimal. Addition and subtraction are done over the least common denominator (LCM of the two denominators), multiplication goes straight across, and division inverts the second fraction and multiplies. The result is then reduced by the greatest common divisor, exactly the way it is taught in school.

Because the arithmetic uses exact integer math (no floating-point rounding), results are correct even for very large numerators and denominators. Everything is calculated locally in your browser, so nothing you enter is sent to a server. Related tools: Fraction Simplifier, GCD Calculator and LCM Calculator.

Frequently asked questions

How do you add fractions with different denominators?

Rewrite both fractions over their least common denominator, then add the numerators. For 1/2 + 3/4 the LCM of 2 and 4 is 4, so 1/2 becomes 2/4 and the sum is (2 + 3)/4 = 5/4, or 1 1/4 as a mixed number. The steps box shows this working for your own numbers.

How do I enter a mixed number like 2 1/3?

Convert it to an improper fraction first: multiply the whole part by the denominator and add the numerator, so 2 1/3 = (2 × 3 + 1)/3 = 7/3. Then enter 7 and 3. The calculator converts results back to mixed numbers for you.

Why is the decimal sometimes marked with ≈?

A fraction only has an exact finite decimal when its simplified denominator contains no prime factors other than 2 and 5. Something like 1/3 = 0.333… repeats forever, so the tool shows a rounded value with the ≈ symbol.

Can it divide by a fraction that equals zero?

No — division by zero is undefined, so if the second fraction has a numerator of 0 (for example 0/5) the calculator shows an error instead of an answer. Denominators of 0 are rejected for the same reason.