LCM Calculator

Find the least common multiple of two or more whole numbers.

Runs in your browser — nothing is sent or saved.

How to use the LCM calculator

  1. Enter two or more whole numbers, separated by spaces or commas.
  2. Read the least common multiple.
  3. See the formula linking it to the greatest common factor.
  4. Copy the link to save or share it.

What the least common multiple is

The least common multiple, or LCM, is the smallest number that every one of your values divides into evenly. For 4 and 6, the multiples of 4 are 4, 8, 12, 16 and the multiples of 6 are 6, 12, 18. The smallest they share is 12, so the LCM of 4 and 6 is 12. This lowest common multiple comes up whenever you add fractions with different denominators or line up repeating events.

The link to the greatest common factor

For two numbers there is a neat shortcut: the LCM equals the two numbers multiplied together, divided by their greatest common factor. So for 4 and 6, that is 4 times 6 divided by 2, which is 24 divided by 2, or 12. The tool uses this relationship, which is fast and exact even for large numbers.

A worked example

Find the LCM of 12, 18, and 24. Take them in pairs. The LCM of 12 and 18 is 36. Then the LCM of 36 and 24 is 72, since 72 is the smallest number both divide into. So the LCM of all three is 72.

FAQ

What is the least common multiple?

It is the smallest positive number that each of your numbers divides into with no remainder. For example, the LCM of 3 and 5 is 15.

How do I find the LCM of two numbers?

Multiply them and divide by their greatest common factor. The tool does this and shows the working, so the LCM of 8 and 12 is 8 times 12 divided by 4, which is 24.

Can I find the LCM of more than two numbers?

Yes. Enter as many whole numbers as you like and the tool works through them in pairs to find the overall least common multiple.

Where is the LCM used?

Most often for adding or comparing fractions, where you need a common denominator, and for problems about events that repeat on different cycles.

Is my information private?

Yes. Everything is calculated in your browser and nothing you enter is uploaded or saved.