Fraction Calculator

How to Use the Fraction Calculator

Enter the numerator (top) and denominator (bottom) for each fraction. For mixed numbers, also enter the whole number in the W field. Select an operation using the operator buttons: +, −, ×, ÷.

The calculator automatically simplifies results to lowest terms using the Greatest Common Divisor (GCD) algorithm. Results are shown as a simplified fraction, decimal, mixed number, and percentage.

Fraction Arithmetic Rules

Addition: a/b + c/d = (ad + bc) / bd Subtraction: a/b − c/d = (ad − bc) / bd Multiplication: a/b × c/d = ac / bd Division: a/b ÷ c/d = a/b × d/c = ad / bc Simplify: divide both by GCD(numerator, denominator)

Common Fraction Operations

Operation	Problem	Result
Add	1/2 + 1/3	5/6
Subtract	3/4 − 1/8	5/8
Multiply	2/3 × 3/4	1/2
Divide	1/2 ÷ 1/4	2

Frequently Asked Questions

Find a common denominator by multiplying the denominators together (or find the Least Common Multiple for simpler results). Convert both fractions to the common denominator, then add the numerators. Example: 1/2 + 1/3. Common denominator = 6. 1/2 = 3/6 and 1/3 = 2/6. Sum = 5/6.

A mixed number combines a whole number and a proper fraction: 2 1/3 means 2 + 1/3 = 7/3 as an improper fraction. To convert: multiply whole by denominator and add numerator (2×3 + 1 = 7), keep same denominator. This calculator accepts mixed numbers in the W (whole) and N/D (fraction) fields.

Find the GCD (Greatest Common Divisor) of numerator and denominator, then divide both by it. Example: 12/18. GCD(12,18)=6. Simplified: 2/3. If GCD=1, the fraction is already in simplest form (irreducible). This calculator simplifies all results automatically.

A fraction with denominator zero (n/0) is undefined — division by zero has no defined value in mathematics. This is because no number multiplied by zero gives a non-zero result. The calculator displays 'Undefined' if a division results in a zero denominator.