LCM Calculator
Find the least common multiple (LCM) of up to 5 numbers. Enter whole numbers and the calculator returns the LCM, which is the smallest positive number divisible by all the inputs. Useful for adding fractions and solving scheduling problems.
LCM examples
| Numbers | LCM |
|---|---|
| 4, 6 | 12 |
| 3, 5 | 15 |
| 12, 18 | 36 |
| 2, 3, 4 | 12 |
| 5, 10, 15 | 30 |
LCM calculator: frequently asked questions
What is the least common multiple (LCM)?
The least common multiple of two or more numbers is the smallest positive number that is divisible by each of the numbers. For example, the LCM of 4 and 6 is 12, because 12 is the smallest number divisible by both 4 and 6.
How do I find the LCM?
The formula is LCM(a,b) = (a * b) / GCD(a,b). First find the GCD (greatest common divisor), then multiply the two numbers and divide by the GCD. For LCM of multiple numbers, apply the formula pairwise.
When would I use the LCM?
LCM is useful for adding fractions (finding a common denominator), scheduling problems (when events repeat at different intervals), and problems involving cycles or repetition.
What is the difference between LCM and GCD?
LCM is the least common multiple (smallest number divisible by both), while GCD is the greatest common divisor (largest number that divides both). For 12 and 18: LCM = 36, GCD = 6.
What is the LCM of numbers with no common factors?
If two numbers share no common factors (are coprime), their LCM is simply their product. For example, LCM(5,7) = 35.
Official sources
- Standard mathematical formula for LCM calculation.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.