LCM Calculator

Free LCM calculator. Find the least common multiple of two or more integers, useful for adding fractions, scheduling, and finding common periods.

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How lcm calculator works

The least common multiple (LCM) of a set of integers is the smallest positive integer that is a multiple of every one of them. For 4 and 6 the multiples are 4,8,12,… and 6,12,18,…, so the LCM is 12. The LCM is the denominator you need when adding or subtracting fractions with different denominators.

This calculator uses the relationship LCM(a, b) = |a × b| / GCD(a, b), extended to more than two numbers by folding: LCM(a, b, c) = LCM(LCM(a, b), c). It accepts a list of integers or a comma- or space-separated string, ignores signs (using absolute values), and rejects zero because the LCM is undefined for zero.

Enter your numbers and click Calculate. The tool returns the LCM and the count of inputs. Use it for fraction arithmetic, scheduling recurring events (when two cycles next coincide), and number-theory homework.

Frequently asked questions

What is the LCM?
The smallest positive integer divisible by every input. For 4, 6, and 8 the LCM is 24, the smallest number divisible by all three.
How is the LCM related to the GCD?
For two numbers, LCM(a, b) × GCD(a, b) = |a × b|. The calculator uses this to compute the LCM from the GCD, which is found with the Euclidean algorithm.
Why is zero not allowed?
The LCM is undefined for zero, because every integer is a "multiple" of zero only in a trivial sense that breaks the definition. The calculator rejects any list containing zero.
Does the order of numbers matter?
No. The LCM is the same regardless of order, and the calculator works with any number of inputs (two or more), accepting integers or a comma/space-separated string.