Factorial Calculator

You can use our Factorial Calculator to calculate the factorial of any real number between 0 and 5,000.

To use this calculator just enter a positive integer number less than or equal to 5000. After you click "Calculate Factorial" the result will be displayed in the output box.

Reference

The factorial of n, or n! is the product of all positive integer numbers from 1 to n.

The value n! is called "n factorial" and is calculated by following formula:

n! = n × (n - 1) × (n - 2) × . . . × 1  ,  n > 0

By convention, 0! = 1

For example, the factorial of 7 is equal to 7×6×5×4×3×2×1 = 5040.

Stirling's Approximation

n! ≈ √2π × n × n ⁿ × e ^-n

Example: 6! ≈ √2π × 6 × 6 ⁶ × e^-6 ≈ √37.6991 × 46656 × 0.002478 ≈ 709.862

Table of Factorials from 1! to 15!

Number (n)	Factorial (n!)
0	1
1	1
2	2
3	6
4	24
5	120
6	720
7	5040
8	40320
9	362880
10	3628800
11	39916800
12	479001600
13	6227020800
14	87178291200
15	1307674368000

You may also be interested in our Summation Calculator