What is the GCF Calculator?
The greatest common factor is the largest whole number that divides all of your numbers without a remainder. It is also called the GCD or HCF and is used to simplify fractions.
How to use the GCF tool
- Enter Numbers separated by commas.
- The result updates instantly as you type, or press Calculate.
- Use Try an example to see how it works, and Reset to start again.
Formula
The tool uses the Euclidean algorithm: GCF(a, b) = GCF(b, a mod b) until the remainder is zero.
Worked example
With numbers separated by commas 48, 36, 60, the greatest common factor comes to 12. Numbers divided by GCF: 4, 3, 5.
Frequently asked questions
Are GCF, GCD and HCF the same?
Yes. They are three names for the same value.
How do I simplify a fraction with GCF?
Divide the numerator and denominator by their GCF.
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Checked by Calcovate · Formula tested against worked examples · Updated 7 Nov 2026 · How we check our calculators.