Least Common Multiple Calculator (LCM)

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On this page is a least or lowest common multiple calculator (LCM calculator). Enter a list of numbers and the LCM tool will return the lowest common multiple of all the numbers.

Close but not quite? Try one of these calculators instead:

Least Common Multiple (LCM) Calculator

What is the Least Common Multiple or Lowest Common Multiple (LCM)?

The Least Common Multiple is the smallest positive integer divisible by all of your inputs. Sometimes, the LCM is the number you get when you multiply all numbers together, other times due to a common factor you can simplify it.

The least common multiple is useful for fractions - the lowest common denominator is just the least common multiple applied to the denominator of a list of fractions.

Finding the Least Common Multiple

Let's find the least common multiple of 63, 3, and 6. (For example, to add the fractions 1/63 + 1/3 + 1/6):

We'll do it using prime factorization and multiplying the highest power of each prime:


In there, we find the primes 2, 3, and 7. Taking the highest power of each and multiplying, we find the LCM:


You could now rewrite the fractions with the denominator 126 (or use the Lowest Common Denominator Calculator).

Using the Least Common Multiple Calculator

Enter a list of numbers where you'd like us to find the least common multiple into the text box up top. The box is forgiving, you can separate numbers with new lines, tabs, commas, and so on.

After, hit the Compute LCM button. We'll quickly produce the Least Common Multiple and report how many numbers were in the text box.

Next, visit our other calculators and tools.

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