GCF / LCM Calculator
Find the greatest common factor and least common multiple of two whole numbers — instantly, in your browser.
Find the greatest common factor (GCF) and least common multiple (LCM) of two whole numbers. The calculation runs in your browser.
How to use it
- Enter two whole numbers.
- Read both results on one line, for example “GCF(12, 18) = 6 — LCM(12, 18) = 36”.
Examples
- 12 and 18: GCF 6, LCM 36.
- 48 and 180: GCF 12, LCM 720.
The two are linked: GCF × LCM = a × b, so 6 × 36 = 12 × 18 = 216.
Good to know
The tool takes two non-zero whole numbers at a time. For three numbers, find the result for two and combine it with the third. The GCF reduces fractions to lowest terms, and the LCM gives the smallest common denominator for adding them. If the GCF is 1 the numbers are coprime and the LCM is their product.
Read how to find the GCF and LCM for Euclid’s method, or the glossary entry.
FAQs
What is HCF?
The highest common factor, another name for the GCF. GCD (greatest common divisor) is the same thing again.
Can I use negative numbers or zero?
No, the tool asks for non-zero whole numbers.