How to Generate a Truly Strong Password in 2026
Password strength isn't about symbols — it's about entropy and randomness. Here's how modern password generators actually work, and how to pick one you can trust.
Founder & Lead Developer
The one rule that actually matters
A password's strength is measured in bits of entropy — the number of guesses an attacker needs on average to crack it. Everything else is noise.
A 16-character password drawn from a 94-symbol alphabet has log₂(94¹⁶) ≈ 105 bits of entropy. That's enough to make offline brute-force attacks infeasible until the heat death of the sun. Add two characters and you're at 118 bits.
Forget "complexity rules" (one uppercase, one symbol). Forget "L3@t5p3@k". The only thing that matters is length × alphabet × randomness.
What makes a generator actually safe
Three properties. Miss any one and the password is broken before you start using it.
1. Cryptographically random
Most language random() functions are not safe. They use pseudo-random generators (PRNGs) designed for speed, not security. Given enough output, an attacker can reverse-engineer the seed and predict every future password.
Safe generators use a cryptographically secure pseudo-random number generator (CSPRNG). In browsers that's crypto.getRandomValues. On Node.js it's crypto.randomBytes. These pull entropy from operating-system sources that are specifically designed to be unpredictable.
If a password generator uses plain Math.random(), throw it away.
2. Runs client-side
Generating a password on a server is an enormous red flag. The generator now knows your password. So does anyone who logs the request. So does anyone who compromises the server.
A trustworthy generator runs entirely in your browser. You can verify this in DevTools: generate a password, open the Network tab, confirm zero network requests. If there's a POST, stop using the tool.
3. Unbiased character selection
Even with a CSPRNG, naive modulo selection (random_byte % alphabet_length) introduces bias — some characters become slightly more likely. For a password generator, this is a minor weakness, but a well-built generator uses rejection sampling to eliminate it entirely.
Why 16 characters? Why 20?
Rule of thumb for 2026:
- 12 characters — fine for throwaway accounts (newsletter signups)
- 16 characters — strong enough for most personal accounts
- 20 characters — recommended for anything important (email, banking, password manager master password)
- 24+ characters — required for encryption keys and root accounts
At 16 characters from a 94-symbol alphabet:
94^16 ≈ 3.7 × 10^31 combinations
≈ 10^22 years to brute-force at 10^9 guesses/sec
More than enough until offline quantum attacks become practical, which is still a decade away from anyone who isn't a nation-state.
The biggest mistake people make
They reuse passwords. A 30-bit password that's unique per site is safer than a 120-bit password used on ten sites. Credential stuffing attacks — using breached passwords from site A to log into site B — are the single biggest source of account compromises.
Always use a password manager. 1Password, Bitwarden, KeePass, whatever you trust. Let the manager generate long random passwords. Your only job is remembering one master password — which should be a long passphrase (e.g. four random dictionary words: 50+ bits of entropy, easy to memorise).
The symbol myth
"Must include at least one symbol" rules give the illusion of security while actually reducing entropy. They constrain the password, making brute-force attacks faster, not slower. Long + random beats complex every time.
If your bank forces a symbol, comply. But don't believe it's helping.
What 3STF Password Generator does
- Uses
crypto.getRandomValues— the browser's CSPRNG - Runs 100% client-side — zero network requests
- Lets you customise length (6-64) and alphabet (upper/lower/digits/symbols)
- Shows live entropy feedback so you know exactly how strong the output is
- Generates passwords with no logging, no storage, no analytics
It's boring by design. A password generator shouldn't be exciting — it should be invisible.
The quick checklist
When you need a password:
- Open a password manager (not a note app, not Excel)
- Use its built-in generator, or one with the three properties above
- Length ≥ 16 for important accounts
- Never reuse across sites
- For the master password, use a 4-6 word passphrase
That's it. Everything else in password security is details.