FREE · EDUCATION & SCIENCE
GCD and LCM Calculator.
Find the greatest common divisor and least common multiple of several numbers, with prime factorisations and Euclid’s algorithm step by step.
Loading the calculator…
How to use GCD and LCM Calculator
Enter whole numbers separated by commas, spaces or new lines. The GCD, LCM, factorisations and Euclid’s steps for the first two numbers update instantly.
How it works
GCD uses Euclid’s algorithm on exact integers; LCM(a, b) = a × b ÷ GCD(a, b), applied across the list.
Example
84, 126 and 210 have a GCD of 42 and an LCM of 1,260; 84 = 2² × 3 × 7.
Questions about GCD and LCM Calculator
Is GCD and LCM Calculator free, and do I need an account?
Yes. This tool is free to use in your browser without an account. Processing takes place on your device.
What are the limits and what should I check?
Up to 50 numbers. GCD and LCM work on very large integers; factorisation is limited to numbers up to 10¹⁸. Everything is calculated in your browser; nothing you type is uploaded. Review the result before using it in your work.
Is my input sent to a server?
Your input is processed in your browser and is not uploaded by this tool. Files and pasted text are cleared when the page is refreshed. Normal website requests are still required to load the page and its libraries. Read the privacy explanation.