How to Create a Strong Passphrase

A strong passphrase is the cheapest, most effective security upgrade you can give yourself. Properly generated, a six-word passphrase is mathematically out of reach of every adversary on Earth — yet it’s something a human can memorize in an afternoon. The Passphrase Generator handles the random selection for you using a cryptographic RNG and the EFF long wordlist.

Why generate, not pick

The single most important rule: don’t choose the words yourself. Humans are bad at randomness. We cluster around common nouns (“dog”, “house”, “happy”), avoid repetition, and unconsciously favor words that sound nice together. A self-picked four-word passphrase often has 20 bits of entropy, not the 51 bits you’d get from a properly random sample. Use a generator backed by crypto.getRandomValues() (or roll dice).

How many words is enough?

Each word from the standard 7,776-word EFF wordlist contributes about 12.9 bits of entropy. Stack them and the security adds up multiplicatively:

• 4 words (~51 bits): fine for routine accounts that don’t gate anything sensitive
• 5 words (~64 bits): appropriate for email, banking, work logins
• 6 words (~77 bits): the recommended minimum for password-manager master passphrases and full-disk encryption keys
• 7+ words: paranoia tier — strong even against state-level adversaries with dedicated hardware

For context: 77 bits of entropy means an attacker running a trillion guesses per second would need about 5 million years to enumerate the space. There is no need to go higher unless you’re protecting nuclear secrets.

Tips and best practices

• Don’t substitute leet-speak. Adding ! and 1 doesn’t help — attackers know to test those mutations. Add a word instead.
• Don’t reuse passphrases across services. A breach at one site exposes everywhere you used the same passphrase. Use a password manager for non-master credentials and let it generate per-site random strings.
• Choose your wordlist deliberately. Short wordlists (~2,000 words) have ~11 bits per word; the EFF long wordlist (~7,776 words) has ~12.9. The difference is small but real — 6 words from the EFF list is meaningfully stronger than 6 words from a smaller list.
• Type it a few times immediately after generating. Muscle memory is the most reliable way to keep a passphrase in your head. Type it five or ten times right after you generate it, before you’ve had a chance to forget.
• Don’t share it. Even with someone you trust. Share access through your password manager’s sharing feature, never the passphrase itself.

When to use a passphrase vs a random password

Use a passphrase for anything you have to type from memory: your password manager’s master passphrase, your laptop login, full-disk encryption keys, SSH key passphrases. For every other account — Twitter, your bank, your email — let your password manager generate a long random string. You won’t memorize those, and you don’t need to.

If you’re not sure whether your passphrase is strong enough, paste it into the Password Strength Checker — it estimates entropy and how long the passphrase would take to crack with realistic attacker hardware. For password-manager-style random strings, use the Password Generator instead. To learn more about the underlying concept, see the passphrase glossary entry.