LCM Calculator

The least common multiple (LCM) of two or more whole numbers is the smallest positive integer that every one of them divides evenly. For 4 and 6, the LCM is 12: it is the smallest number that is a multiple of both 4 and 6. It is also called the lowest common multiple.

The fastest method uses the GCF: lcm(a, b) = (a × b) ÷ gcd(a, b). For more than two numbers, fold: lcm(a, b, c) = lcm(lcm(a, b), c). This calculator runs that fold and shows the intermediate results.

GCF is the largest number that divides every input. LCM is the smallest number that every input divides into. They are connected: for any pair of positive integers a and b, a × b = gcf(a, b) × lcm(a, b). So once you know the GCF you can compute the LCM with a single division.

Adding and subtracting fractions with different denominators (the lowest common denominator is the LCM of the denominators), aligning periodic events that repeat at different intervals, and number-theory problems. Any time you need to find a common cycle or shared rhythm, the LCM is the answer.

Yes. Separate the numbers with commas or spaces, for example '12, 18, 30'. The calculator folds across the list pairwise.

LCM grows quickly when the inputs are coprime. For example, lcm(7, 11, 13, 17) = 17,017. With a handful of larger coprime numbers the result can blow past JavaScript's safe-integer range. The calculator flags this case and asks for smaller inputs.