Factorial calculator
Compute exact factorials for integers 0 to 1000; 20! = 2,432,902,008,176,640,000.
- Runs in your browser
- No upload
- Instant result
Assumptions & formula
Formula and assumptions
n! = ∏₁ⁿ i; 0!=1; 0≤n≤1000
Results
Enter values and press Calculate to see the result here.
How to use this calculator
- Set inputs and units
Enter a whole number n from 0 to 1,000. A factorial multiplies all positive integers up to n.
- Calculate
Check this worked example: 20! =2432902008176640000 (19 digits); 0! =1
- Results
Copy the exact integer text instead of forcing it into a spreadsheet’s floating-point number.
Questions and limits
Why is zero factorial one?
The empty product is 1, which is consistent with (n+1)!=(n+1)n! at n=0.
Which input errors should I correct?
Negative or fractional inputs are rejected. Scientific notation must still stand for an exact integer that is accepted.
What does this calculation leave out?
An exact BigInt factorial with limits. It is not a gamma-function continuation, and it doesn't compute permutations or combinations.