Factorial Calculator – Find n! Instantly Online
Calculate factorials, see step-by-step solutions, and learn about factorial mathematics
Factorial Calculator
Instant Calculation
Quickly calculate factorials with our optimized algorithm.
Fully Responsive
Works perfectly on all devices – desktop, tablet, and mobile phones.
Calculation Results
About Factorials
What is a Factorial?
The factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n.
For example: 5! = 5 × 4 × 3 × 2 × 1 = 120
Special Case
By definition, the factorial of 0 is 1: 0! = 1
This is known as the empty product, and it’s consistent with the combinatorial interpretation of there being exactly one way to arrange zero objects.
Applications
- Combinatorics: Calculating permutations and combinations
- Probability: Computing binomial coefficients
- Series expansions: Taylor series and mathematical analysis
- Computer science: Algorithm analysis and recursive functions
Growth Rate
Factorials grow at an extremely fast rate. For example:
- 10! = 3,628,800
- 20! ≈ 2.433 × 10¹⁸
- 50! ≈ 3.041 × 10⁶⁴
- 100! ≈ 9.333 × 10¹⁵⁷
Why Use Factorial Calculator Pro?
Privacy Focused
All calculations happen in your browser. Your data never leaves your device.
No Waiting
Get instant results without any delays or server requests.
Step-by-Step Solutions
Understand how factorials are calculated with detailed steps.
Beautiful Interface
Enjoy a clean, modern design with intuitive controls and smooth animations.
Factorial Calculator – Get Factorials Right Away (2025)
How to Use the Factorial Calculator
Only two simple steps:
1. Type in a Whole Number
- Enter any non-negative integer from 0 to 170
- ✅ 0! = 1 (by mathematical definition)
- Works for 5, 10, 25, 100, and beyond
2. Get Results Right Away
✅ See the full result (e.g., 6! = 720)
✅ Scientific notation for large values (e.g., 100! ≈ 9.33 × 10¹⁵⁷)
✅ One-click copy or reset
✅ Works on iPhone, Android, and desktop
✅ No email, no login, no cost
Key Features
- ⚡ Instant Computation: Results in under 1 second
- 🔢 Full Range Support: 0 to 170 (maximum usable factorial)
- ✅ Correct Edge Handling: 0! = 1 implemented per standard math
- 📱 Fully Responsive: Works on all devices
- 🔒 Browser-Only Processing: Your input never leaves your device
- 🧼 Clean Light UI: Simple, uncluttered, ad-free
- 📋 One-Click Copy: Paste results into notes, code, or reports
- 🧮 Math-First Design: No distractions—just pure calculation
Frequently Asked Questions (FAQs)
Q: What does a factorial mean?
The factorial of a non-negative integer n, written n!, is the product of all positive integers ≤ n.
Example: 4! = 4 × 3 × 2 × 1 = 24. By definition, 0! = 1.
Q: Is this factorial calculator truly free?
Yes! No trials, sign-up, or hidden costs—100% free.
Q: Why is 170 the highest value?
Beyond 170, the result exceeds the maximum number in IEEE 754 double-precision format (≈1.8 × 10³⁰⁸). Values >170 return Infinity.
Q: Can I calculate (-5)!?
No. Factorials are only defined for non-negative integers. Negative or decimal inputs return an error.
Q: Does it work on phones?
Yes! Fully optimized for iPhone and Android.
Q: Is my information safe?
Absolutely. We never save or track your input. All math runs in your browser.
Q: Can I use it for programming?
Yes! Perfect for validating recursive or iterative factorial functions in your code.
Q: Who can use this tool?
Ideal for students, teachers, coders, statisticians, and anyone working with discrete mathematics.
Related Tools
- Average Calculator – Find mean, median, and mode of data sets
- Percentage Calculator – Solve percentage problems in finance and stats
- Homepage
Trusted by Educators Worldwide
For authoritative, free learning on factorials and their applications, we recommend Khan Academy – Factorials and Permutations —a globally trusted resource used by millions of students and teachers to master combinatorics and probability.
✅ Get your factorial now—quickly, for free, and always confidential.
Use the free Factorial Calculator from Toolsspark.