BIP-39

BIP-39 is a standard that turns a random number into a list of 12–24 words from a fixed 2,048-word list. A wallet uses that list to rebuild the seed, from which it derives all keys.

BIP stands for “Bitcoin Improvement Proposal”, and the number points to one specific document. The standard calls for 128 to 256 bits of randomness and adds a short checksum to it. The whole thing is split into 11-bit pieces, and each piece is one word. That gives 12, 15, 18, 21 or 24 words. Then a special function with 2,048 rounds turns the words and an optional passphrase into a 512-bit seed.

This design has a practical effect: the same recovery phrase works in many wallets from different makers, so you’re not tied to one device. To be safe, check compatibility before you move funds, because some programs use their own variants.

The standard doesn’t say how to store the phrase. That’s up to you. For people who want to split it, there’s SLIP-39.

Why it matters for your family

Knowing the phrase follows a standard is reassuring: in 10 years, it won’t be readable only by the device that created it. An heir can restore it in any compatible program. Still, write down which standard and how many words you use. The guide on how to store a seed phrase explains how to protect the paper.