Overview
Enter two or more positive whole numbers, separated by commas, to find their greatest common divisor - the largest number that divides evenly into all of them. Computed using the Euclidean algorithm, applied pairwise across however many numbers you enter. Useful for simplifying fractions to their lowest terms, solving ratio problems, or checking schoolwork. Runs entirely client-side.
Best for: Simplifying a fraction to its lowest terms
How to use this tool
- Enter your numbers. Two or more positive whole numbers, separated by commas.
- GCD is computed instantly. Calculated using the Euclidean algorithm, applied pairwise so any count of numbers works.
- Read the result. The greatest common divisor updates live as you edit the list.
Frequently asked questions
The GCD is computed pairwise: the GCD of the first two numbers is found, then that result is combined with the third number, and so on - mathematically equivalent to finding the GCD of all numbers at once.
GCD finds the largest number that divides evenly into all your inputs; LCM finds the smallest number that all your inputs divide evenly into - opposite operations, both useful for fraction and ratio problems. Use the LCM Calculator for that direction.