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LCM Calculator

Find the least common multiple of two or more whole numbers. See the prime factorization, the highest power of each prime, the GCF method steps, and the listed multiples. Everything runs in the browser.

  • 2 to 20 numbers
  • Prime factorization
  • Step-by-step work
  • Stays on your device

The least common multiple (LCM), also called the lowest common multiple or least common denominator when working with fractions, is the smallest positive number that every number in the list divides into evenly.

Prime factorization

  • 4 = 2^2
  • 6 = 2 × 3
  • 10 = 2 × 5

LCM = 2^2 × 3 × 5 = 60

Take each prime at its highest power in any of the numbers, then multiply.

GCF method steps

  1. LCM(4, 6) = 4 × 6 ÷ 2 = 12
  2. LCM(12, 10) = 12 × 10 ÷ 2 = 60

Numbers stay on this device. Nothing is uploaded, and there is no account.

The least common multiple is the smallest number that every number in your list divides into evenly. It is the number you need to add or subtract fractions with different denominators, and it answers questions like when two repeating schedules will line up again.

Example: 4 = 2^2, 6 = 2 × 3, and 10 = 2 × 5. The highest power of each prime is 2^2, 3, and 5, so the LCM is 4 × 3 × 5 = 60.

Find the largest shared factor with the GCF calculator, break one number into primes with the factoring calculator, reduce a ratio with the ratio calculator, divide step by step with the long division calculator, or solve A / B = C / D with the proportion calculator. Browse more tools in the Math hub.

How to use the LCM calculator

  1. Type two or more whole numbers, separated by commas or spaces.
  2. Read the LCM and the GCF in the result panel.
  3. Check the prime factorization to see the highest power of each prime.
  4. Follow the GCF method steps or the listed multiples to see how the LCM was found.

Frequently asked questions

What is the LCM?

The least common multiple (LCM) is the smallest positive number that every number in a set divides into with no remainder. The LCM of 4 and 6 is 12, because 12 is the first number that both 4 and 6 go into evenly.

How do I find the LCM of two numbers?

List the multiples of each number until you find the first one they share, or use the formula LCM(a, b) = a × b ÷ GCF(a, b). For 12 and 18 the GCF is 6, so the LCM is 12 × 18 ÷ 6 = 36.

How do I find the LCM with prime factorization?

Break each number into primes, then take every prime at the highest power it appears in any of the numbers and multiply. 8 = 2^3, 12 = 2^2 × 3, and 18 = 2 × 3^2, so the LCM is 2^3 × 3^2 = 72.

Can I find the LCM of three or more numbers?

Yes. Find the LCM of the first two numbers, then the LCM of that result and the next number, and so on. The LCM of 4, 6, and 10 is 60. This calculator takes up to 20 numbers at once.

What is the difference between LCM and GCF?

The LCM is the smallest number that all of your numbers divide into. The greatest common factor (GCF) is the largest number that divides all of them. For 12 and 18 the LCM is 36 and the GCF is 6. For two numbers, LCM × GCF equals the product of the numbers.

How is the LCM used with fractions?

The LCM of the denominators is the least common denominator. To add 1/4 + 1/6, the LCM of 4 and 6 is 12, so rewrite them as 3/12 + 2/12 = 5/12.

What is the LCM of two prime or coprime numbers?

If two numbers share no factor other than 1, their LCM is simply their product. The LCM of 7 and 11 is 77, and the LCM of 8 and 15 is 120.

Is my information saved or uploaded?

No. The LCM calculator runs entirely in your browser. Numbers are not sent to a server or stored, and there is no account.

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