Math & School

GCD and LCM calculator

GCD and LCM of two or three numbers, with a worked example.

Updated on May 25, 2026 Calculator, calculation path and examples on one page

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Calculator

Examples

12 and 18 → gcd 6, kgv 36.

gcd: 6

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8 and 12 → gcd 4, kgv 24.

gcd: 4

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6, 8 and 12 → gcd 2, kgv 24.

gcd: 2

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FAQ

What is the GCD?

The greatest common divisor is the largest number by which all entered numbers are divisible without a remainder.

What is the kgV?

The least common multiple is the smallest number that is a multiple of all the numbers entered.

How are gcd and kgv related?

For two numbers the following applies: a × b = gCD(a, b) × kgV(a, b).

What do you need the GCD for?

Especially for reducing fractions: the numerator and denominator are divided by their GCD.

Why do you need the kgV?

Especially for finding the main denominator when adding and subtracting fractions.

Can I also enter three numbers?

Yes. Enter the third number. Leave it at 0 if you only need two numbers.

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Sources and notes