Calculate the factorial of any number instantly, with big-number support.
The Factorial Calculator computes n! — the product of every positive integer up to n — for any number you enter. It returns the exact result instantly, even for large inputs whose answers run to many digits, making it handy for probability, combinatorics, and quick homework or engineering checks.
The factorial of a non-negative integer n, written n!, is the result of multiplying all the whole numbers from 1 up to n. Factorials grow extremely fast, which is why they appear whenever you count arrangements or combinations of items. By convention, 0! equals 1, because there is exactly one way to arrange nothing.
Factorials are the engine behind counting problems. The number of ways to arrange n distinct items in order is exactly n!, which is why they anchor the formulas for permutations and combinations in probability and statistics. They also appear in power-series expansions in calculus, in algorithms that enumerate possibilities, and in everyday questions like how many ways a deck can be shuffled. Because the values explode so quickly — 13! already exceeds six billion — being able to compute them exactly is genuinely useful.
Calculate 5 factorial:
55 × 4 × 3 × 2 × 1120So there are 120 different ways to order five distinct items. Enter a larger number, such as 20, and the tool returns the full exact value (2,432,902,008,176,640,000) without rounding.
Many pocket and phone calculators switch to scientific notation once a factorial grows past a certain size, giving you an approximation like 2.43 × 1018 instead of the true integer. For counting problems, probability, and code verification, the exact value matters — an approximation can hide the last several digits you actually need. This tool returns the complete integer, so you can trust the result even for large inputs, and copy it directly into your work without rounding surprises.
The factorial of n (written n!) is the product of all integers from 1 to n. For example, 5! = 120.
By definition, 0! equals 1.
Yes — it computes large factorials accurately without losing precision.
Factorials are defined for non-negative integers; enter a whole number for a valid result.
Basic calculators approximate large factorials; this tool returns the full exact integer instead.
Yes. Calculation runs locally in your browser.
Explore the Fibonacci Sequence Generator and the Date Calculator for more everyday math.
How to Use Factorial Calculator
Type the non-negative integer you want the factorial of.
The factorial is computed instantly.
Copy the result for your work.
Calculate the factorial of any number instantly, with big-number support.
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Sep 11, 2026Type:
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