GCD & LCM Calculator
Find the greatest common divisor and least common multiple of two or more numbers.
How to use the GCD & LCM Calculator
Enter whole numbers separated by commas. Uses the Euclidean algorithm.
Formula
gcd(a, b) = gcd(b, a mod b) lcm(a, b) = a × b ÷ gcd(a, b)
Worked example
gcd(12, 18, 30) = 6 and lcm(12, 18, 30) = 180.
Frequently asked questions
Where is LCM used?
Adding fractions (common denominators), scheduling repeating events and gear ratios.
Results are estimates for educational and planning purposes. Always confirm important financial, health or legal decisions with a qualified professional. Last reviewed 2026-09-27.