Why the BIP39 Wordlist Has Exactly 2,048 Words
BIP39 uses a 2,048-word dictionary so each word encodes exactly 11 bits of entropy, balancing phrase length with human usability and error prevention.
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Contents
- The Mathematics of 11 Bits per Word
- Trade-offs Between Dictionary Size and Phrase Length
- Linguistic Constraints and Collision Avoidance
- Hardware and Implementation Constraints
- FAQ
- Sources
- Keywords:
- seed phrase · entropy · mnemonic
Guides on the same subject
- Seed Phrase Examples: 12, 18 and 24 BIP39 Mnemonic Phrases
Real BIP39 seed phrase examples for 12, 18 and 24 words from the official test vectors, with their entropy, checksum bits and why random words fail.
- 12 vs 24 Word Seed Phrase: Which Is More Secure?
A 24-word seed phrase has 256 bits of entropy and a 12-word one 128, but both are beyond brute force; 24 words help mainly when part of a backup is exposed.
- BIP39 Passphrase: How the 25th Word Creates a Hidden Wallet
A BIP39 passphrase, the 25th word, is mixed into the seed, so the same words open a separate hidden wallet; a typo opens an empty one, so back it up exactly.
One of the documents in the Seed Phrase PDF Archive, listed on archive page 1.