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Quick answer: enter two or more numbers above — the calculator instantly finds their greatest common factor, e.g. GCF of 8 and 12 is 4.
GCF calculator
Short answer: the GCF (greatest common factor) is the largest number dividing all your numbers evenly — e.g. GCF(12, 18, 24) = 6. Enter numbers above for an instant answer.
Greatest common factor
Short answer: the greatest common factor of 8 and 12 is 4 — the largest divisor they share. The calculator uses Euclid's algorithm, extended across all numbers.
How to find the GCF
Short answer: list each number's factors and take the largest shared one — or let the calculator do it. For 12 and 18: factors of 12 are 1, 2, 3, 4, 6, 12; of 18 are 1, 2, 3, 6, 9, 18; GCF = 6.
Frequently asked questions
What is the GCF of 8 and 12?
4. Factors of 8: 1, 2, 4, 8. Factors of 12: 1, 2, 3, 4, 6, 12. Largest shared: 4. Enter any numbers above for an instant answer.
What is the difference between GCF and GCD?
Nothing — GCF (greatest common factor) and GCD (greatest common divisor) are two names for the same thing. HCF (highest common factor) is a third name.
How do you find the GCF of three numbers?
Find the GCF of the first two, then the GCF of that result with the third. The calculator does this automatically — enter up to 12 numbers.
What is the GCF used for?
Simplifying fractions (divide top and bottom by the GCF), factoring polynomials, and solving ratio problems.
What is the GCF of 100 and 75?
25. Tap the preset above to verify instantly.
Is this GCF calculator free?
Yes — unlimited calculations, free forever. No account, no limits. Everything runs in your browser.