LCM Calculator

Its most common job is adding and subtracting fractions: the LCM of the denominators is the common denominator, so LCM(4, 6) = 12 turns 1/4 + 1/6 into twelfths. It also answers scheduling questions — if one bus runs every 4 days and another every 6, they coincide every 12 days — and any problem where cycles of different lengths must line up.

They are opposites in spirit. The GCF is the largest number that divides into all your numbers (it is never bigger than the smallest of them); the LCM is the smallest number that all your numbers divide into (it is never smaller than the largest of them). For two numbers they are linked: LCM × GCF = the product of the two numbers, as in 12 × 2 = 4 × 6.

Coprime numbers share no prime factors, so a common multiple must contain every prime factor of both numbers at full strength — nothing can be shared or overlapped. The smallest such number is exactly the product, which is why LCM(5, 7) = 35 and LCM(4, 9) = 36.

Yes — enter three or more numbers and the prime factor method handles them together, taking the highest power of each prime across the whole set. Doing it by hand, the reliable route is pairwise: find the LCM of the first two, then find the LCM of that result and the next number, and repeat.

With 1, nothing changes: the LCM is the LCM of the remaining numbers, since every number is a multiple of 1 in the sense required — LCM(1, 6) = 6. With 0, the answer is 0 by convention, because 0 is the only multiple of 0, so it is the only common multiple available.

No. It runs 100% in your browser, so the numbers you enter are processed locally on your device and are never uploaded, stored or shared with anyone.