Factorial Calculator
Exact factorials with steps and digit counts.
Frequently Asked Questions
What is a factorial?
The factorial of n, written n!, is the product of all whole numbers from n down to 1: 5! = 5 x 4 x 3 x 2 x 1 = 120. By definition, 0! equals 1.
Why does this calculator stay exact for big numbers?
Normal floating point loses accuracy beyond about 16 digits, so the calculator uses big-integer arithmetic to give the exact value of factorials up to 1000!, which has 2,568 digits.
Where are factorials used?
Factorials count arrangements: n distinct items can be ordered in n! ways. They appear throughout probability, combinatorics, and series expansions in calculus.
Is the Factorial Calculator free, and is my data private?
Yes. It is completely free and every calculation runs locally in your browser, so the numbers and dates you enter are never uploaded, stored, or shared with anyone.
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