GCD & LCM Calculator
Find the greatest common divisor and least common multiple of a list of numbers.
Greatest common divisor (GCD)
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Least common multiple (LCM)
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Coprime?
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Results update as you type.
About this calculator
This calculator finds the greatest common divisor (GCD) — the largest number that divides all your values evenly — and the least common multiple (LCM), the smallest number they all divide into. It works on two or more whole numbers using the Euclidean algorithm.
Frequently asked questions
How is the GCD calculated?
It uses the Euclidean algorithm: repeatedly replace the larger number with the remainder of dividing the two, until one becomes zero. The other is the GCD.
How are GCD and LCM related?
For two numbers, GCD × LCM = the product of the numbers. So LCM = a × b ÷ GCD, which is how the tool extends the LCM across a whole list.
Results are estimates for general guidance only, not financial, medical or tax advice.