What makes a password strong?

The strength of a random password is measured in bits of entropy. Entropy is the log base 2 of the number of possible passwords that could have been generated under the same rules. A password drawn uniformly from an alphabet of N symbols and of length L has entropy of L × log₂(N). A 24-character password drawn from 94 printable ASCII characters carries about 157 bits — well beyond what any classical or feasible quantum attack can brute-force in any meaningful timeframe.

EntropyResistanceRecommendation
< 50 bitsWeakAvoid for any sensitive account.
50–70 bitsOnline attacksOK with rate limiting.
70–100 bitsOffline attacksAcceptable for most secrets.
100+ bitsLong-term storageRecommended for vault masters.

Where the randomness comes from

This tool uses crypto.getRandomValues(), a cryptographic-grade source backed by the operating system's entropy pool. It is the same source used by browsers for TLS, WebCrypto signatures, and crypto.randomUUID(). No pseudo-random number generator like Math.random() is used.

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Never paste a generated password into a tool you don't trust. This page generates passwords locally and never transmits them, but the only way to be sure is to verify the source. Pair this tool with a reputable password manager and 2FA wherever possible.

FAQ

Should I memorize a password this strong?

Generally, no. Use a password manager (1Password, Bitwarden, KeePassXC, the built-in macOS/iOS/Chrome managers) to store generated passwords. Memorize only your vault master password — make it a long passphrase rather than a random string.

What's a good length?

For most accounts, 16 characters drawn from all four classes (lower, upper, digit, symbol) is more than enough. Bump to 24+ for vault master passwords, root credentials, and recovery codes.

Why exclude ambiguous characters?

Useful when a password must be read aloud or hand-copied. The trade-off is a slightly smaller character set, which means slightly less entropy per character — keep the length the same and the impact is negligible.

Are passphrases better than random strings?

For things you must type often (vault master, full-disk encryption), a Diceware-style passphrase of 6 or more random words from a large list is easier to remember and still cryptographically strong. For non-memorable passwords stored in a manager, random strings are more compact.