Enter two or more whole numbers to find their greatest common factor.

The greatest common factor

The greatest common factor is the largest whole number that divides every number in your set without a remainder. For twenty four, thirty six, and sixty it is twelve. It is the tool you reach for when reducing a fraction to lowest terms or simplifying a ratio.

The same idea is called the greatest common divisor in many textbooks. When two numbers share no common factor other than one, their greatest common factor is one and they are described as coprime. This calculator uses the efficient Euclidean method to find it.

The formula

Worked example

The greatest common factor of 24, 36, and 60 is 12.

How to read your result

The greatest common factor is the largest number that divides all your inputs evenly. It is what you use to reduce a fraction to lowest terms.

Frequently asked questions

What is the GCF used for?

Reducing fractions and simplifying ratios are the most common uses.

Is GCF the same as GCD?

Yes, greatest common factor and greatest common divisor are the same thing.

What if the numbers share no factors?

Then the GCF is 1, and the numbers are called coprime.

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