Factorial Calculator
Calculate the factorial of a whole number, useful for permutations, combinations and probability problems.
Your results
Calculation breakdown
- Factorial
- n! = n × (n−1) × (n−2) × ... × 1, with 0! = 1
Worked example
6! = 6 × 5 × 4 × 3 × 2 × 1 = 720.
Assumptions
- 0! is defined as 1 by convention.
- Inputs above 170 are rejected since the result exceeds double-precision accuracy.
How this calculator works
This calculator multiplies a whole number by every positive whole number below it down to 1 to find its factorial, commonly used in permutation, combination and probability calculations. Results are capped for very large inputs to avoid unusable numbers.
Frequently asked questions
What is 0 factorial?
By mathematical convention, 0 factorial equals 1.
Can I find the factorial of a negative number?
No, factorials are only defined for non-negative whole numbers, so the calculator shows an error for negative inputs.
Why is there a maximum input limit?
Factorials grow extremely fast, so inputs above 170 produce numbers too large to display accurately in standard double-precision maths.
Editorial review and responsibility
Reviewed by the CalcAussie editorial team on 21 September 2026. Review scope: Method, Australian terminology, material assumptions, source links and user-facing limitations.
Calculator results remain estimates based on the figures entered. Check material decisions against current official information and report a suspected error so it can be reproduced and corrected.