What does this tool do?
The GCD & LCM Calculator finds the greatest common divisor (GCD) and least common multiple (LCM) of the numbers you enter. It helps everyone from students simplifying fractions to designers adjusting ratios.
How to use it
- Enter your values into the fields.
- The result is calculated instantly.
- Read or copy the result.
How GCD and LCM work
The GCD is the largest integer that divides two or more numbers without a remainder; the LCM is the smallest number that is a common multiple of them all. For example, for 12 and 18 the GCD is 6 and the LCM is 36. The tool computes the GCD with the fast Euclidean algorithm, then derives the LCM via 'a × b / GCD'. When you enter more than two numbers, the operation chains pairwise to produce a single result for all of them.
Everyday and classroom uses
Use the GCD of numerator and denominator to reduce fractions to their simplest form; when adding fractions with different denominators, the LCM gives you the common denominator. The LCM also solves timing problems, such as finding how often two recurring events land on the same day. Enter your numbers separated by commas or spaces and the result appears instantly on screen.
Frequently asked questions
Can I enter more than two numbers at once?
Yes. When you enter several numbers, the tool finds the GCD and LCM of the first two, then folds the result with each subsequent number, returning a single GCD and LCM for the whole set.
What happens if one of the numbers is 0?
If a number is 0, the GCD is taken as the other number itself, but the LCM with 0 is mathematically undefined, so positive integers are recommended for meaningful results.
Is GCD & LCM Calculator free?
Yes. GCD & LCM Calculator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. GCD & LCM Calculator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.