LCM and HCF Calculator IE
Find the LCM (lowest common multiple) and HCF/GCD (highest common factor) of two or more whole numbers instantly.
How it works
Enter two or more whole numbers separated by commas. The calculator returns both the lowest common multiple (LCM) and the highest common factor (HCF, also called the GCD).
Frequently asked questions
What is the LCM?
The least common multiple is the smallest number that two or more numbers all divide into exactly. The LCM of 12 and 18 is 36.
What is the HCF?
The highest common factor (also called GCD or GCF) is the largest number that divides the given numbers exactly. The HCF of 12 and 18 is 6.
How do I find the LCM?
Break each number into prime factors and multiply the highest power of every prime that appears in any of them.
How do I find the HCF?
Find the prime factors common to all the numbers and multiply them together.
What is the relationship between LCM and HCF?
For two numbers, LCM × HCF equals the product of the numbers — a quick way to check your result.
What is the difference between LCM and HCF?
The HCF is the largest factor shared by the numbers; the LCM is the smallest multiple they all share.
LCM & HCF Calculator
This calculator finds the LCM (least common multiple) and HCF (highest common factor, also called GCD or GCF) of two or more numbers.
What they mean
The HCF is the largest number that divides all of them exactly. The LCM is the smallest number that all of them divide into exactly.
Using prime factors
Break each number into prime factors. The HCF multiplies the primes they share; the LCM multiplies the highest power of every prime that appears.
Worked example
For 12 (2²×3) and 18 (2×3²): HCF = 2×3 = 6, and LCM = 2²×3² = 36.
A handy shortcut
For two numbers, LCM × HCF = the product of the numbers. Here 6 × 36 = 216 = 12 × 18, which is a quick way to check your answer.
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