Password Generator
Generate secure, cryptographic random passwords.
This random password generator creates strong, unpredictable passwords by combining uppercase and lowercase letters, numbers, and symbols, using a length and character set you choose. It's built for one-off account creation, not for remembering or reusing passwords across sites.
Choose your desired length and which character types to include, and the generator returns a random password instantly.
Worked Calculation Examples
| Scenario | Result | Calculation Step |
|---|---|---|
| 12 characters, full character set (94 printable characters) | ≈78.6 bits of entropy | log2(94) ≈ 6.55. 12 × 6.55 ≈ 78.6 bits - well above the commonly cited 60-bit threshold for a strong password. |
| 16 characters, lowercase letters and digits only (36 characters) | ≈82.7 bits of entropy | log2(36) ≈ 5.17. 16 × 5.17 ≈ 82.7 bits - a smaller pool offset by extra length still produces strong entropy. |
What Makes a Password Strong
Password strength comes primarily from length and randomness, not complexity rules alone - a longer random password is exponentially harder to crack than a shorter one, even with fewer character types. Mixing uppercase, lowercase, numbers, and symbols adds further entropy on top of length. The 'entropy' terminology borrows directly from information theory, formalized by mathematician Claude Shannon in a landmark 1948 paper, where it measures the average unpredictability of a system in bits - the same mathematical concept used to measure password strength is what also underlies data compression and encryption elsewhere in computing.
Random vs. Memorable Passwords
A fully random password generated by a tool like this is far more secure than a memorable one you create yourself, since human-created passwords tend to follow predictable patterns (common substitutions, personal information, dictionary words) that attackers specifically test for. Use a password manager to store random passwords rather than trying to memorize them.
How to Use the Password Generator
- Open the Password Generator and enter the values requested in the input fields.
- Check the units, percentages, dates, or time periods before reading the answer.
- Review the instant result and adjust any value to compare another scenario.
- Use the formula, example, and FAQs below to understand how the password generator works.
Frequently Asked Questions
How long should a strong password be?
At least 12-16 characters is a common modern recommendation - longer passwords are exponentially harder to crack through brute-force methods, even more so than adding extra symbol types to a shorter password.
Is a randomly generated password safer than one I create myself?
Yes - human-created passwords tend to follow predictable patterns attackers already anticipate, while a truly random password has no exploitable pattern, making it significantly more resistant to guessing and cracking attempts.
Should I reuse a generated password across multiple accounts?
No - use a unique password for every account. If one site is breached, reused passwords let attackers access your other accounts too; a password manager makes storing unique passwords practical.
How do I use this password generator?
Enter the known values, review the units or settings, and the calculator updates the result instantly. The formula and example on this page show how the answer is produced.
What does the Password Generator calculate?
Generate secure, cryptographic random passwords. It is designed for fast browser-based calculations without sign-up, downloads, or manual spreadsheet setup.
What formula does this password use?
The formula is: Entropy (bits) = length × log2(character pool size). The character pool size is how many distinct characters could appear at each position (26 lowercase + 26 uppercase + 10 digits + symbols, depending on what is enabled). Multiplying the password length by log2 of that pool size gives the entropy in bits - a measure of how many guesses a brute-force attack would need on average.
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Last updated: September 29, 2026.