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!

You may also be interested in our Summation 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!

You may also be interested in our Summation Calculator