Factorial calculator

Calculate a factorial as an exact whole number.

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Factorial calculator processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

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Nonnegative whole number

Answer

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The factorial of n is the product of integers from 1 through n. By definition, 0! = 1.

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Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Saved scenario

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Formula and assumptions

Whole numbers from 0 to 1000 are supported. The integer answer is exact, even when too large for ordinary floating-point arithmetic.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Factorial calculator

The factorial of n is the product of integers from 1 through n. By definition, 0! = 1.

Whole numbers from 0 to 1000 are supported. The integer answer is exact, even when too large for ordinary floating-point arithmetic.

Next: Proportion calculator

A worked example

With nonnegative whole number = 5, the factorial is 120.

Next: Permutation combination calculator

Before you use the result

Whole numbers from 0 to 1000 are supported. The integer answer is exact, even when too large for ordinary floating-point arithmetic.

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ToolOctopus. “Factorial calculator.” Updated 2026-09-26. https://tooloctopus.com/factorial-calculator.

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