GCF Calculator
Calculate the greatest common factor (GCF), also known as the greatest common divisor (GCD), of two whole numbers.
- Free to use
- Accurate results
- No registration required
- Works on all devices
Enter two whole numbers to calculate their greatest common factor (GCF) and least common multiple (LCM).
Your result
6
Greatest common factor
Least common multiple36
AI explanation
Formula
GCF computed via the Euclidean algorithm; LCM = (a × b) / GCFWorked example
12 and 18
| Field | Value |
|---|---|
| First number | 12 |
| Second number | 18 |
| Greatest common factor | 6 |
| Least common multiple | 36 |
Assumptions
- Both numbers must be positive whole numbers.
Frequently asked questions
What is the greatest common factor?
It's the largest whole number that divides evenly into both numbers — also called the greatest common divisor (GCD).
How is GCF calculated?
This calculator uses the Euclidean algorithm, which repeatedly replaces the larger number with the remainder of dividing it by the smaller number until the remainder is zero.
What is GCF used for?
GCF is used to simplify fractions to their lowest terms, solve problems involving equal grouping, and as a building block for the Least Common Multiple (see the LCM Calculator).