Password Generator
Adjust the password length with the slider, select the character types you want, and click 'Generate Password'. Click 'Copy' to copy it to your clipboard.
How the Password Generator Works
Our free online password generator creates cryptographically secure random passwords using the Web Crypto API built into your browser. Every password is generated entirely on your device — nothing is ever sent to a server. Simply choose your desired length (8–64 characters), toggle the character sets you want (uppercase, lowercase, numbers, symbols), and click Generate Password. The tool instantly produces a strong, unpredictable password and shows you its entropy rating so you know exactly how secure it is.
Why Strong Passwords Matter
Weak passwords remain the number-one cause of data breaches. According to Verizon's Data Breach Investigations Report, over 80 % of hacking-related breaches involve stolen or weak credentials. Cybercriminals use automated brute-force attacks, dictionary attacks, and credential-stuffing tools that can test billions of combinations per second. A short, predictable password like "password123" or "qwerty" can be cracked in under one second.
A truly random password with sufficient length and character diversity is your first line of defence. The longer and more complex the password, the more combinations an attacker must try — making brute-force attacks computationally infeasible.
Understanding Password Entropy
Password entropy is a measure of unpredictability, expressed in bits. The formula is:
Entropy = L × log₂(R)
where L is the password length and R is the size of the character pool. For example, a 16-character password using uppercase, lowercase, digits, and 27 symbols has a pool of 89 characters:
Entropy = 16 × log₂(89) ≈ 103 bits
Security experts generally recommend at least 80 bits of entropy for important accounts and 128+ bits for critical systems.
Common Password Mistakes
Avoid these pitfalls that weaken your security:
- Reusing passwords across multiple sites — one breach exposes them all.
- Using personal information like birthdays, pet names, or addresses.
- Simple substitutions like "p@ssw0rd" — attackers know these tricks.
- Short passwords under 12 characters, regardless of complexity.
- Dictionary words or common phrases, even with numbers appended.
- Sharing passwords via email or messaging apps in plain text.
NIST Password Guidelines
The National Institute of Standards and Technology (NIST) updated its Digital Identity Guidelines (SP 800-63B) with modern recommendations:
- Passwords should be at least 8 characters minimum, with 15+ strongly recommended.
- Allow passwords up to 64 characters or more.
- Do not require periodic password changes unless a breach is suspected.
- Do not impose arbitrary composition rules (e.g., must contain one symbol).
- Screen passwords against lists of commonly compromised passwords.
- Support password managers and paste functionality in password fields.
- Enable multi-factor authentication wherever possible.
Password Length vs. Time to Crack
The table below shows approximate brute-force cracking times assuming 100 billion guesses per second (a high-end modern GPU cluster) with a full 95-character ASCII set:
| Length | Possible Combinations | Estimated Time to Crack |
|---|---|---|
| 8 | 6.6 × 10¹⁵ | ~1 minute |
| 10 | 5.9 × 10¹⁹ | ~7 days |
| 12 | 5.4 × 10²³ | ~170 years |
| 14 | 4.9 × 10²⁷ | ~1.5 billion years |
| 16 | 4.4 × 10³¹ | ~14 trillion years |
| 20 | 3.6 × 10³⁹ | Practically impossible |
As the table shows, every additional character multiplies the difficulty exponentially. A 12-character password is orders of magnitude stronger than an 8-character one.
Password Manager Recommendations
No one can memorise dozens of unique, random, 16+ character passwords. That is why security experts universally recommend using a password manager. These tools store all your passwords in an encrypted vault protected by a single master password. Popular, reputable options include:
- Bitwarden — open-source, free tier available, cross-platform
- 1Password — excellent user experience, family and team plans
- KeePassXC — fully offline, open-source, local database
- Dashlane — built-in VPN and dark-web monitoring
Use your password manager to generate and autofill unique passwords for every account. Combined with two-factor authentication, this approach provides robust protection against most attack vectors.
Frequently Asked Questions
Is this password generator safe to use?
Yes. The password is generated entirely in your browser using the Web Crypto API. No passwords are transmitted to or stored on any server. You can even use this tool offline.
How long should my password be?
Security experts recommend at least 12–16 characters for standard accounts and 20+ characters for high-security accounts such as banking, email, or cryptocurrency wallets. Longer passwords are exponentially harder to crack.
What is password entropy?
Entropy measures how unpredictable a password is, expressed in bits. Higher entropy means more possible combinations an attacker must try. A password with 80+ bits of entropy is considered strong; 128+ bits is excellent.
Should I use symbols and numbers in my password?
Including a variety of character types (uppercase, lowercase, numbers, and symbols) increases the character pool and thus the entropy. However, length is generally more important than complexity — a 20-character lowercase password is stronger than an 8-character password with all character types.
How often should I change my passwords?
NIST no longer recommends routine password rotation. Change your password immediately if you suspect a breach, but otherwise a strong, unique password managed by a password manager can remain in use indefinitely.
Related Tools
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- Random Number Generator — Generate random numbers in a range
- JSON Formatter — Format and validate JSON data
Sources
- NIST Special Publication 800-63B — Digital Identity Guidelines: NIST.gov
- Verizon 2023 Data Breach Investigations Report: Verizon DBIR
- OWASP Password Storage Cheat Sheet: OWASP.org
- Electronic Frontier Foundation — Creating Strong Passwords: EFF.org