• 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:

https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki