This LCM calculator finds the least common multiple of two or more whole numbers: the smallest number that all of them divide into evenly.
How the LCM is calculated
LCM(a, b) = a × b ÷ GCF(a, b)
For more than two numbers, the calculator finds the LCM of the first two, then of that result and the next number, and so on.
Worked example
For 4, 6 and 10: LCM(4, 6) = 24 ÷ 2 = 12, and LCM(12, 10) = 120 ÷ 2 = 60. The LCM is 60.
Frequently asked questions
When do I need the LCM?
Adding or subtracting fractions with different denominators needs a common denominator, and the LCM is the smallest one. It also answers questions like “when will two buses that leave every 4 and 6 minutes next leave together?”
How is LCM related to GCF?
For two numbers, GCF × LCM = a × b. Find the GCF with the GCF calculator.