Skip to content
Free Tools Galaxy
!
100% free · no signupRuns in your browser

Factorial Calculator

n! for any non-negative integer up to 170.

Best for: Use it in probability, permutations and combinations, or series expansions.

Complete guide

Input

How it's calculated & sources
The Factorial Calculator uses the standard, deterministic formula, so the same inputs always produce the same result. It runs entirely in your browser, so your inputs are never uploaded. Last reviewed June 2026.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

How it works

n! = n × (n−1) × (n−2) × … × 1, with 0! = 1.

Example

5! = 120

Frequently asked questions

Why is 0! = 1?+

By definition — it's the empty product and makes formulas like nCr work consistently.

Continue your journey

Where people usually head next.

📏
Significant Figures Calculator
Count significant figures in a number and round to a chosen number of sig figs.
🎯
Percent Error Calculator
Measure how far a measured value is from the true value, as a percentage.
🔬
Scientific Notation Converter
Convert numbers between standard decimal form and scientific (and E) notation.
🧪
Scientific Calculator
Evaluate expressions with sin, cos, log, ln, sqrt, π and e.

Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is Factorial?
A factorial calculator multiplies a whole number by every positive integer below it.
Why does Factorial matter?
The number of ways to arrange n distinct items in order. Factorials grow extremely fast - 20! already exceeds a quintillion.
How is Factorial calculated?
It multiplies n by n - 1, down to 1. By definition 0! = 1. Formula: n! = n x (n - 1) x (n - 2) x ... x 1; 0! = 1.
What are common factorial mistakes?
Trying to take the factorial of a negative or non-integer.
When should you use the Factorial Calculator?
Use it in probability, permutations and combinations, or series expansions.

What is the Factorial Calculator?

A factorial calculator multiplies a whole number by every positive integer below it.

How the Factorial Calculator works

It multiplies n by n - 1, down to 1. By definition 0! = 1.

n! = n x (n - 1) x (n - 2) x ... x 1; 0! = 1

Factorial reference: n! for n = 1 to 20

1!1
2!2
3!6
4!24
5!120
6!720
7!5,040
8!40,320
9!362,880
10!3,628,800
11!39,916,800
12!479,001,600
13!6,227,020,800
14!87,178,291,200
15!1,307,674,368,000
16!20,922,789,888,000
17!355,687,428,096,000
18!6,402,373,705,728,000
19!121,645,100,408,832,000
20!2,432,902,008,176,640,000

Common mistakes to avoid

  • Trying to take the factorial of a negative or non-integer.
  • Underestimating how fast factorials overflow.
  • Forgetting that 0! = 1, not 0.

Keywords: factorial.

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the Factorial Calculator free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the Factorial Calculator?+

Factorial Calculator uses the standard factorial formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The Factorial Calculator runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the Factorial Calculator on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

Explore more

Popular tools

📝
Word Counter
Count words, characters, sentences and reading time.
🔤
Case Converter
Convert text to UPPER, lower, Title and Sentence case.
🔁
Text Reverser
Reverse any text instantly.
🧹
Remove Duplicate Lines
Strip duplicate lines from any list.

Explore other categories

🧾
SSI Payment Calculator
Estimate your 2026 monthly Supplemental Security Income (SSI) from your income and living situation.
🏦
PPF Calculator
Project your Public Provident Fund maturity with a full year-by-year schedule.
💼
EPF Calculator
Estimate your Employees' Provident Fund corpus at retirement.
🧓
NPS Calculator
Project your National Pension System corpus, lump sum and monthly pension.
Related searches: variance calculator, correlation coefficient calculator, scientific calculator

Smart Autopilot

AI-style routing · 100% on-device

Based on this tool, your recent activity and how others chain tools together.

Likely next step

📏Significant Figures CalculatorTop match🎯Percent Error CalculatorMeasure how far a measured value is from the true value, as a percentage.🔬Scientific Notation ConverterConvert numbers between standard decimal form and scientific (and E) notation.🧪Scientific CalculatorEvaluate expressions with sin, cos, log, ln, sqrt, π and e.➕Simple CalculatorBasic arithmetic for two numbers: add, subtract, multiply, divide.½Fraction CalculatorAdd, subtract, multiply and divide fractions with auto-simplification.

Smart recommendations

Next best tool

σ²
Variance Calculator
Sample or population variance from a data set.

Also worth a look

📋
SGPA Calculator
Semester Grade Point Average for a single term.
💓
Target Heart Rate Calculator
Karvonen formula target HR zone for cardio.
❤️‍🔥
Heart Rate Zone Calculator
Five training zones from max heart rate.
📝
Word Counter
Count words, characters, sentences and reading time.

Share & publish

Share & challenge

Twitter Facebook LinkedIn WhatsApp
Share-to-grow kit (Reddit, LinkedIn, Medium)
Reddit post
Title: I built/used this free factorial calculator — instant, no signup

Body: n! for any non-negative integer up to 170. Try it: https://freetoolsgalaxy.com/tools/factorial-calculator
LinkedIn post
Factorial Calculator on Free Tools Galaxy — n! for any non-negative integer up to 170. https://freetoolsgalaxy.com/tools/factorial-calculator
Medium intro
# Factorial Calculator — the free tool I keep coming back to

n! for any non-negative integer up to 170.

Try it: https://freetoolsgalaxy.com/tools/factorial-calculator
Quora answer
The fastest way is to use a free in-browser factorial calculator: https://freetoolsgalaxy.com/tools/factorial-calculator. n! for any non-negative integer up to 170.

Embed this tool anywhere

Free embed code for blogs, docs and dashboards. Every embed sends a backlink home — helping you and the galaxy grow together.

HTML iframe
Drop into any site — auto-resizes to its content height, theme-aware.
<iframe src="https://freetoolsgalaxy.com/tools/factorial-calculator?embed=1" title="Factorial Calculator" loading="lazy"
  style="width:100%;height:600px;border:0;border-radius:16px;background:#0b1020"
  allow="clipboard-write"></iframe>
<script>window.addEventListener("message",function(e){if(e.data&&e.data.type==="ftg-embed-height"){document.querySelectorAll("iframe").forEach(function(f){if(f.contentWindow===e.source){f.style.height=e.data.height+"px";}});}});</script>
<p><a href="https://freetoolsgalaxy.com/tools/factorial-calculator" target="_blank" rel="noopener">Powered by Factorial Calculator on Free Tools Galaxy</a></p>
Responsive wrapper
Aspect-locked container — good for blog post bodies.
<div style="position:relative;padding-bottom:75%;height:0;overflow:hidden;border-radius:16px">
  <iframe src="https://freetoolsgalaxy.com/tools/factorial-calculator?embed=1" title="Factorial Calculator" loading="lazy"
    style="position:absolute;inset:0;width:100%;height:100%;border:0" allow="clipboard-write"></iframe>
</div>
WordPress / Markdown
Paste in a custom-HTML block or markdown file.
[Factorial Calculator — free online tool](https://freetoolsgalaxy.com/tools/factorial-calculator)

<iframe src="https://freetoolsgalaxy.com/tools/factorial-calculator?embed=1" width="100%" height="600" frameborder="0"></iframe>
Text link-back
Minimal credit link — best for sidebars and footers.
<a href="https://freetoolsgalaxy.com/tools/factorial-calculator" target="_blank" rel="noopener">Try the free Factorial Calculator</a>

Share-to-Grow Kit

Pre-written, ready-to-paste posts for every major channel. Help others discover this tool — and earn backlinks.

Title
I built a free mortgage calculator that works instantly in the browser — no signup, no ads in your face
Body
Hey r/[subreddit],

I kept needing a quick mortgage calculator and most options online were slow or behind paywalls, so I built one that:

• Runs 100% in your browser (your data never leaves your device)
• No signup, no email wall, no popups
• Loads in under a second on mobile

It covers the standard mortgage use cases (mortgage, home, loan, payment) and links out to the formula + worked examples if you want to learn the math.

Link: https://freetoolsgalaxy.com/tools/mortgage-calculator

Happy to take feedback — what's missing?
Post to a relevant subreddit (e.g. r/InternetIsBeautiful, r/webdev, r/productivity). Avoid spammy subs.
Developer & SEO tools