LCM and GCD Calculator
Find the Least Common Multiple and Greatest Common Divisor of any numbers.
LCM vs GCD — what's the difference?
The GCD (Greatest Common Divisor, also called GCF or HCF) is the largest number that divides all inputs exactly. It is used to simplify fractions. The LCM (Least Common Multiple) is the smallest positive number that is divisible by all inputs. It is used to find a common denominator when adding fractions. For two numbers: LCM(a,b) = (a × b) ÷ GCD(a,b).
Frequently asked questions
Can I find the LCM/GCD of more than two numbers?
Yes. Enter as many numbers as you need, separated by commas or spaces. The calculator applies the Euclidean algorithm iteratively to find GCD and LCM of all numbers at once.
What is the GCD used for in fractions?
To simplify a fraction, divide both numerator and denominator by their GCD. For example, 12/18 → GCD(12,18) = 6 → 2/3.
