Least Common Multiple Calculator
Find the LCM (Least Common Multiple) of two or more integers — the smallest positive number divisible by all of them.
How to use the Least Common Multiple Calculator
- Enter your inputs into the Least Common Multiple Calculator above.
- Results update instantly as you type — no submit button needed.
- Adjust any value to see how the result changes in real time.
The LCM via GCD
LCM(a, b) = (a × b) / GCD(a, b) · · · LCM of 3+ numbers: pairwise apply
For two numbers, LCM × GCD = product of the numbers. For more than two, apply pairwise: LCM(a,b,c) = LCM(LCM(a,b), c).
Worked example
LCM(12, 18): GCD is 6, so LCM = (12 × 18)/6 = 36. LCM(4, 6, 10): LCM(4,6) = 12; LCM(12,10) = 60.
Frequently asked questions
When do I use LCM in real life?
Adding fractions with different denominators (find common denominator), scheduling repeating events that coincide, gear ratios, music theory and project scheduling.
Is LCM the same as common multiple?
Common multiples are any number divisible by all given numbers. LCM is the smallest such positive number. Multiples of LCM are also common multiples (LCM × 2, LCM × 3, etc.).
What if one number is 0?
LCM is undefined when any number is 0. Some calculators return 0; mathematically, 0 has no positive multiples, so no LCM exists.