Maths Calculators

Factorial Calculator

Calculate the factorial of any non-negative integer instantly with this free online factorial calculator.

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Factorial Calculator

Enter a non-negative whole number from 0 to 1000 to calculate its factorial.

Enter a whole number between 0 and 1000.

How factorials work: The factorial of a non-negative integer n, written as n!, is the product of all positive integers from 1 through n. By definition, 0! = 1.
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What Is a Factorial Calculator?

A factorial calculator calculates the factorial of a non-negative whole number. A factorial is represented by an exclamation mark after a number, such as 5!, and is calculated by multiplying that number by every positive whole number below it.

Factorials are commonly used in mathematics, combinatorics, probability, statistics and computer science. This calculator provides an immediate result without requiring you to perform a long multiplication manually.

Why Use the Factorial Calculator?

The YesTools Factorial Calculator provides a quick and straightforward way to calculate factorials while reducing the risk of arithmetic errors.

1

Instant Results

Calculate a factorial immediately after entering a valid number.

2

Accurate Calculations

Results are calculated using JavaScript BigInt arithmetic to maintain exact integer values.

3

Free to Use

The calculator is available online without a subscription or payment.

4

Works in Your Browser

The calculation is performed directly in your browser without sending the number to a server.

5

Supports 0!

The calculator correctly handles zero factorial, which is defined mathematically as 1.

6

Copy Results

Copy the calculated factorial directly to your clipboard for use elsewhere.

How to Use the Factorial Calculator

Calculating a factorial takes only a few steps.

  1. Enter a number — Enter a non-negative whole number between 0 and 1000 into the calculator.
  2. Calculate the factorial — Select the Calculate Factorial button.
  3. Review the result — The calculator displays the exact factorial and the corresponding calculation.
  4. Copy the result — Select Copy Result if you need to transfer the factorial to another application.

How to Calculate a Factorial

The factorial of a non-negative integer is calculated by multiplying the number by every positive integer below it. The mathematical notation is n!, where n represents the number being evaluated. For example, 5! is calculated as 5 × 4 × 3 × 2 × 1, which equals 120.

Factorials increase very quickly as the input number becomes larger. For example, 10! is 3,628,800, while 20! is 2,432,902,008,176,640,000. This rapid growth makes a calculator useful when working with larger values.

Factorial Formula

For a positive integer n, the factorial formula is n! = n × (n − 1) × (n − 2) × ... × 2 × 1. The special case of zero factorial is 0! = 1.

Examples of Factorials

Common factorials include 1! = 1, 2! = 2, 3! = 6, 4! = 24, 5! = 120, 6! = 720, 7! = 5,040, 8! = 40,320, 9! = 362,880 and 10! = 3,628,800.

Factorial Calculator Accuracy and Limits

This calculator accepts non-negative whole numbers from 0 through 1000. Decimal values and negative numbers are not valid factorial inputs under the standard definition used by this tool.

The calculator uses JavaScript BigInt arithmetic rather than ordinary floating-point number calculations. This allows the tool to produce exact integer results for the supported range without introducing rounding errors.

James William Steven Parker, creator of YesTools
Created by

James William Steven Parker

Creator & Developer of YesTools

James William Steven Parker is a web developer and technology professional with extensive experience in web development, web design, SEO, web hosting, systems analysis and cybersecurity. He created YesTools to provide fast, practical and free online tools for everyday tasks and technical work.

Learn more about James and YesTools

Frequently Asked Questions

A factorial is the product of a non-negative integer and every positive integer below it. It is written using an exclamation mark. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120.
0 factorial, written as 0!, equals 1. This is a mathematical convention that is important in combinatorics, probability and other areas of mathematics.
To calculate n!, multiply n by every positive integer below it until reaching 1. For example, 6! = 6 × 5 × 4 × 3 × 2 × 1 = 720.
This calculator accepts non-negative whole numbers from 0 to 1000. Decimal numbers, negative numbers and other invalid inputs are rejected.
10 factorial is 3,628,800. It is calculated as 10 × 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1.
Yes. The YesTools Factorial Calculator is free to use and calculates results directly in your browser.

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