What is the LCM Calculator?
Find the least common multiple (LCM) of two or more positive integers with this free online LCM calculator. Enter numbers separated by commas and get the LCM, GCD, prime factorizations, and step-by-step work using both the prime-factor method and the GCD formula lcm(a, b) = a × b ÷ gcd(a, b). Runs entirely in your browser with no signup.
How to use the LCM Calculator
- Enter at least two positive integers (comma, space, or newline separated).
- Click Calculate LCM.
- Review the LCM and GCD results.
- Check each number's prime factorization and the combined LCM factors.
- Copy the LCM or the full summary with steps.
Common use cases
- Finding LCM(12, 18) = 36 for fraction addition
- Computing LCM(12, 18, 8) = 72 for a word problem
- Checking LCM(5, 7) = 35 for coprime numbers
Frequently asked questions
- What is the least common multiple (LCM)?
- The LCM of a set of numbers is the smallest positive integer that is divisible by every number in the set. For example, LCM(4, 6) = 12.
- How is LCM calculated here?
- The tool merges prime factorizations (taking the highest exponent for each prime) and verifies the result by chaining lcm(a, b) = a × b ÷ gcd(a, b) across all inputs.
- Does it also show GCD?
- Yes. The greatest common divisor (GCD) of all input numbers is shown alongside the LCM, since the two are closely related.
- How many numbers can I enter?
- Between 2 and 20 positive integers, each up to 10 billion. Large LCM results use arbitrary-precision arithmetic.
