BIP39: Bitcoin Improvement Proposal 39 


  • BIP39 is an open-source cryptography standard proposed in 2013 by Marek Palatinus, Pavlov Ruslav, Aaron Voisine and Sean Bowe. It defines a cryptographic implementation process that consists of two parts:
    • Generating a mnemonic seed from a very large random number.
    • Converting a mnemonic seed into a binary seed

  • Most hardware and software wallets are compatible with BIP39

  • A BIP39 seed is composed of 12, 15, 18, 21 or 24 words.

  • With BIP39, each word can be uniquely identified by its four first letters and all words are pulled from a specific wordlist that will never change:


  • To create a BIP39 mnemonic seed, the initial random binary value, together with its checksum, is split into 11 bits segments and each is then translated into seed words.


  • Each 11 bits segment represents a decimal number between 0 and 2047 and serves as an index in BIP39 specific wordlist to convert the initial number into an easily readable form. That is why this list is made of 2048 words.

Initial entropy + checksum

Recovery seed length

Encryption level

128 bits + 4 bits

12 words

128 bits

160 bits + 5 bits

15 words

160 bits

192 bits + 6 bits

18 words

192 bits

224 bits + 7 bits

21 words

224 bits

256 bits + 8 bits

24 words

256 bits


More detailed information can be found on: