Overview
What Is a Factorial?
A factorial (written n!) is the product of all positive integers from 1 up to n. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120.
Calculate the factorial of any non-negative integer instantly.
A factorial (written n!) is the product of all positive integers from 1 up to n. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120.
Useful for permutations, combinations, probability calculations, and algebra.
Type a whole number into the field.
The result updates automatically.
0! equals 1 by mathematical convention, not 0.
No, factorials are only defined for non-negative integers.
Standard factorial is only defined for integers - decimal factorials require the Gamma function, which this calculator doesn't compute.
Each additional number multiplies the running product, causing exponential-like growth.
It can compute large factorials, though extremely large results may display in scientific notation due to size.
Permutations, combinations, probability, and series expansions in calculus all use factorials.
1! equals 1.
Using an exclamation point after the number, like 5! for 'five factorial'.
n! = n × (n-1) × (n-2) × ... × 1
Yes, completely free with no sign-up required.