Factorial Calculator

Calculate factorials for integers from 0 to 170.

How to use Factorial Calculator

Calculate factorials for integers from 0 to 170.

  1. Enter the requested values in the relevant fields.
  2. Check the units and calculation options.
  3. Compare the result with the assumptions in your scenario.

Inputs are processed in your browser unless the tool explicitly states that it retrieves reference data. Verify the result against your own context before making an important decision.

Factorial example and edge case

5! equals 5 × 4 × 3 × 2 × 1, which is 120. By definition, 0! equals 1. Factorials are commonly used in permutations, combinations and probability.

Values grow quickly: 20! is about 2.43 × 1018. Consider display and numeric limits for large inputs; factorials of negative integers are outside this calculator's scope.