Entropy is the only number that matters
A password's strength is how many guesses an attacker needs, and that is set by how it was made, not by how it looks. A password chosen uniformly at random from N possibilities has log₂ N bits of entropy; every extra bit doubles the work. Sixteen random characters from a 94-symbol set give 16 × log₂ 94 ≈ 105 bits. Five random words from a 6,032-word list give 5 × 12.6 ≈ 63 bits, and are far easier to type and remember.
Patterns people invent do not count. “Summer2026!” has eleven characters from a large set but maybe 25 bits of real entropy, because crackers try capitalised words, years and a trailing symbol first. The “rate mine” mode penalises the common patterns, but it can only estimate; a generated secret is the only one with a known entropy.
How much is enough
| Use | Bits | Why |
|---|---|---|
| Website login behind rate limiting | 40–50 | Online guessing is slow; the real risk is reuse, so make it unique. |
| Anything that could leak as a hash (most accounts) | 60–70 | Offline cracking of bcrypt/Argon2 runs at tens of thousands of guesses per second per GPU. |
| Master password, disk encryption, SSH key passphrase | 80+ | Fast hashes or long-term secrets; must survive hardware improving for decades. |
| Cryptographic keys and API tokens | 128+ | Not typed by humans, so there is no cost to length. |
Passphrases
The word list here is 6,032 common English words of 4–7 letters chosen by frequency, similar in spirit to the EFF long list (7,776 words, 12.9 bits each). Words are picked with uniform randomness, so the phrase is as strong as its bit count regardless of how ordinary the words are. Adding a capital letter or a number to satisfy a form's rules adds a few bits at most; adding a sixth word adds twelve.
Use a manager
The best password is one you never see: let a password manager generate a long random one per site and remember it. Use this page for the few secrets you must type yourself: the manager's master password, your login password, and encryption passphrases.
Questions
Is this generator safe to use?
Randomness comes from crypto.getRandomValues, the same source browsers use for TLS keys, and the page has no network code. Still, for your most important secrets prefer a password manager or a generator running offline, since any web page could in principle be modified in transit; reading the source here is a 100-line task.
Are passphrases really stronger than complex passwords?
A five-word passphrase (63 bits) beats a typical eight-character “complex” password (about 30–40 bits of real entropy) by a huge margin, and you can remember it. A random 16-character password (105 bits) is stronger still, but belongs in a manager.
How is time-to-crack calculated?
Expected guesses are 2^(bits−1) (half the space, on average), divided by the attacker’s rate. The rates shown range from 10 per second (online, throttled) to 10¹¹ per second (a GPU rig against MD5). The right row depends on how the service stores your password, which you usually do not know, so assume the fast one.
Should I change passwords regularly?
Not on a schedule; change them when there is a reason (a breach, a shared device, a departing colleague). Forced rotation leads to weaker, patterned passwords. NIST guidance since 2017 says the same.