GCD & LCM Calculator
Find the greatest common divisor and least common multiple of two or more numbers instantly, free and easy right in your browser.
Enter Values
Minimum 1
Minimum 1
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How to use this calculator
- Enter two whole numbers.
- Press Calculate for the GCD and LCM.
How it works
The GCD (greatest common divisor) is the largest number that divides both. The LCM (lowest common multiple) is the smallest number both divide into: LCM = a × b ÷ GCD.
Worked example
12 and 18. GCD = 6, LCM = 12 × 18 ÷ 6 = 36.
Common mistakes
- Mixing up GCD (largest common factor) and LCM (smallest common multiple).
- Entering 0, which has no meaningful GCD/LCM with another number.
Frequently asked questions
What's the difference between GCD and LCM?
GCD is the largest number that divides both; LCM is the smallest number both divide into.
How are they related?
For two numbers, GCD × LCM equals the product of the two numbers.
What are GCD and LCM used for?
GCD simplifies fractions and ratios; LCM finds a common denominator or when repeating events line up again.
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Cite this tool
Zerdly. (2026). GCD & LCM Calculator. Retrieved from https://www.zerdly.com/tools/gcd-lcm-calculator/
Tip: Enter any known values to calculate the remaining results.
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