GCD and LCM calculator
Find the GCD and LCM of two or more numbers instantly.
Free GCD and LCM calculator
Find the greatest common divisor (GCD) and least common multiple (LCM) of two or more numbers. Enter your numbers separated by commas and get both results instantly. The GCD is the largest number that divides them all; the LCM is the smallest number they all divide into. Handy for fractions, ratios and scheduling problems.
Use cases
- Simplify fractions: divide numerator and denominator by their GCD (12/18 ÷ 6 = 2/3).
- Add or subtract fractions: use the LCM of the denominators as the common denominator.
- Equal sharing: the GCD gives the largest equal group without mixing (24 and 36 sweets → boxes of 12).
- Calendar overlaps: two events every 6 and 8 days coincide again every LCM = 24 days.
- Gears and cycles: the LCM tells you when two cogwheels return to their start position.
FAQ
How is the GCD found? With the Euclidean algorithm. How is the LCM related? For two numbers, LCM = (a × b) ÷ GCD.