What is GCD (greatest common divisor)?

GCD is the largest positive integer that divides each number with no remainder. It is also called HCF.

What is LCM (least common multiple)?

LCM is the smallest positive integer that is a multiple of each number.

Can I enter more than two numbers?

Yes. Enter a comma-separated list like 12, 18, 30. The calculator reduces pairwise across the list.

Do negative numbers work?

Yes. GCD and LCM are computed using absolute values. LCM is reported as a positive number.

GCD(a, 0) = |a|. LCM(a, 0) is 0 by convention. If all inputs are 0, both results are 0.

How are GCD and LCM related?

For two integers a and b (not both 0), |a×b| = GCD(a,b) × LCM(a,b).

GCD / LCM Calculator

Enter integers to calculate GCD (HCF) and LCM. Supports multiple numbers (comma-separated) and shows Euclidean steps for the first two.

Numbers (comma-separated)

Integers only. Examples: 12,18 · 24, 60, 90 · negatives allowed.

Result will appear here.

Privacy: calculations run locally in your browser. No inputs are stored or transmitted.

How it works

GCD (Euclidean algorithm): repeatedly apply division with remainder until remainder is 0.
LCM: for two numbers, LCM(a,b) = |a×b| ÷ GCD(a,b) (when not both 0).
For multiple numbers, compute pairwise: GCD(a,b,c) = GCD(GCD(a,b),c), similarly for LCM.

Examples

12, 18 → GCD = 6, LCM = 36
24, 60, 90 → GCD = 6, LCM = 360
-8, 12 → GCD = 4, LCM = 24
10, 0 → GCD = 10, LCM = 0

When to use this tool

This tool is designed for quick, practical tasks such as everyday calculations, data formatting, or simple conversions. It is best used when you need fast results without installing software or using complex tools.

When to use

Quick checks or one-time calculations
Validating or converting data before using it elsewhere
Simple tasks that do not require advanced software

When not to use

Critical financial, legal, or medical decisions
Large-scale or automated processing
Situations requiring guaranteed precision beyond basic validation

Always review results before using them in important contexts.

About this tool

This tool helps you perform quick utility operations directly in your browser. It runs entirely in your browser without sending data to a server.

You can use this tool when handling simple tasks without installing additional software. The results should be interpreted as a processed output based on your input data.

FAQ

What is GCD (greatest common divisor)?
GCD is the largest positive integer that divides each number with no remainder. It is also called HCF.
What is LCM (least common multiple)?
LCM is the smallest positive integer that is a multiple of each number.
Can I enter more than two numbers?
Yes. Enter a comma-separated list like 12, 18, 30. The calculator reduces pairwise across the list.
Do negative numbers work?
Yes. GCD and LCM are computed using absolute values. LCM is reported as a positive number.
What about zeros?
GCD(a, 0) = |a|. LCM(a, 0) is 0 by convention. If all inputs are 0, both results are 0.
How are GCD and LCM related?
For two integers a and b (not both 0), |a×b| = GCD(a,b) × LCM(a,b).