CM CalcMentor Calculators that explain the answer.

Number theory

Least Common Multiple Calculator

Calculate the smallest positive multiple shared by all entered numbers.

When LCM helps

LCM is useful for adding fractions with unlike denominators, scheduling repeating events and finding when cycles align.

Example

For 12, 18 and 30, the least common multiple is 180. That is the smallest positive number divisible by all three values.

LCM vs GCF

The least common multiple is a shared multiple. The greatest common factor is a shared divisor. Use LCM to find a common denominator; use GCF to simplify a fraction.

Common mistakes

Do not choose the first large number that all values divide into if a smaller shared multiple exists. The LCM must be the smallest positive shared multiple.

Last reviewed: 2026-05-17

Before relying on this result

Use this calculator together with the formula, assumptions, limitations and examples on the page. If the topic involves health, tax, lending, investment, legal, safety or current-rate decisions, treat the number as an estimate and check the relevant primary source or professional guidance.

Calculator metadata last reviewed: 2026-05-14.