BIP39 Passphrase Generator

BIP39 (Bitcoin Improvement Proposal 39) defines a standard for generating mnemonic sentences from a word list. While originally designed for cryptocurrency wallet seed phrases, the concept of memorable multi-word passphrases is widely useful for any secure password.

Strength is measured in bits of entropy. With a 200-word list, each word adds ~7.6 bits. A 6-word passphrase has ~45.9 bits of entropy, and a 12-word passphrase has ~91.7 bits — comparable to a random 14-character password with mixed case, digits, and symbols.

The full BIP39 list is optimised for cryptocurrency seed recovery and contains some uncommon words. This tool uses a curated 200-word subset of common English words to maximise memorability while still providing strong entropy.

Spaces are the most readable, dashes work well in systems that do not allow spaces, and periods are useful for domain-name-style identifiers. Choose whichever works best with the system where you will use the passphrase.

Yes. Words are selected using crypto.getRandomValues(), the browser's cryptographically secure random number generator. Each word is chosen independently and uniformly from the list.