Factorial Calculator

Calculate the factorial of any number instantly. Free, accurate, and 100% private.

✨ Calculate Factorial

📥 ENTER A NUMBER (0 – 170)

What Is a Factorial?

A factorial is a mathematical operation represented by an exclamation mark (!). The factorial of a number n, written as n!, is the product of all positive integers from 1 up to n.

For example, 5! = 5 × 4 × 3 × 2 × 1 = 120.

The Formula

By definition: 0! = 1 and 1! = 1.

Factorial Table (0! to 10!)

Why Use Our Factorial Calculator?

Our tool is fast, accurate, and free. It handles numbers up to 170! (the largest factorial JavaScript can compute accurately), shows the expansion steps, and calculates extra info like digit count and trailing zeros.

Key Features

• ⚡ Instant factorial calculation
• 📐 Shows expansion steps
• 🔢 Handles up to 170!
• 📊 Shows digit count and trailing zeros
• 🧮 Displays scientific notation
• 🔐 100% private — nothing leaves your browser

Real-World Uses

• 🎲 Probability — permutations and combinations
• 📊 Statistics — binomial distributions
• 💻 Programming — recursion examples
• 🎓 Math education — combinatorics basics
• 🔐 Cryptography — key generation algorithms

Perfect For

❓ Frequently Asked Questions

What is a factorial?

The product of all positive integers from 1 to n. Represented by n!. Example: 5! = 120.

What is 0! (zero factorial)?

By mathematical convention, 0! = 1. This is important for combinatorics formulas.

Is this Factorial Calculator free?

Yes, 100% free with no signup, no download, and no usage limits.

What is 5! (5 factorial)?

5! = 5 × 4 × 3 × 2 × 1 = 120.

What is 10! (10 factorial)?

10! = 3,628,800.

Can factorial handle negative numbers?

No. Factorial is only defined for non-negative integers (0, 1, 2, 3…).

Can factorial handle decimals?

Not in the standard definition. Decimal factorials require the Gamma function, which is outside the scope of this tool.

What is the largest factorial supported?

Up to 170!, because JavaScript can accurately compute numbers up to about 1.8 × 10^308.

How is factorial used in real life?

Factorial is used in probability (permutations), statistics (binomial coefficients), computer science (recursion), and cryptography.

What are permutations?

Permutations are the number of ways to arrange items. The formula is n! / (n − r)!, where r is the number of items you’re arranging.