Glossary A–Z

Seed phrase

A seed phrase is the list of words that backs up a self-custody crypto wallet. Whoever has the words controls the wallet.

By TokenTrail Editorial2 min read · 7 sources
Hand holding a pile of grain seeds

Photo: “Free dry paddy seeds hand” by Unknown, CC0 1.0, via Rawpixel (edited: cropped and resized).

Quick answer

A seed phrase is a list of 12 to 24 words, generated by your wallet, that encodes the random number behind all of its private keys [1]. It is the master key to the wallet: anyone who has it can access every account, so never share it [2].

Key points

  • 1Also called a recovery phrase, secret recovery phrase or mnemonic.
  • 2The common standard, BIP39, uses 12 to 24 words from a fixed list of 2,048.
  • 3It restores the whole wallet on a new device. Lose it and the device, and the funds are gone.

How does a seed phrase work?#

When you create a self-custody wallet, the software generates 128 to 256 bits of randomness, adds a short checksum and splits the result into 11-bit chunks. Each chunk picks one word from a list of 2,048, giving a phrase of 12 to 24 words [1]. The words are then converted into a 512-bit binary seed [1], and the BIP32 standard derives a whole tree of key pairs from that single seed [3]. That is why a single phrase can restore all past and future addresses in the wallet [4].

StepValue
12 words128 bits of entropy + 4-bit checksum
18 words192 bits of entropy + 6-bit checksum
24 words256 bits of entropy + 8-bit checksum
Possible 12-word phrases2¹²⁸ ≈ 3.4 × 10³⁸

What is the difference between a seed phrase and a private key?#

A private key controls one account or address. The seed phrase sits one level above: it is the root from which the wallet derives many private keys, so it controls all of them together [2]. Custodial exchange accounts usually have no seed phrase for you to keep, because the exchange holds the keys and you log in with a password [5].

What should you remember about it?#

  • A randomly generated phrase is practically impossible to guess; the real risks are theft and loss.
  • BIP39 allows an optional extra passphrase; each passphrase opens a different wallet, so a forgotten one cannot be recovered [1].
  • Keep more than one copy in separate safe places [4].
  • If anyone else has seen your phrase, move your funds to a new wallet with a new phrase.
  • Full guide: seed phrases explained.

Frequently asked questions#

Is a recovery phrase the same as a seed phrase?

Yes. Seed phrase, recovery phrase, secret recovery phrase and mnemonic are different names for the same list of words [2].

Can I recover my wallet without the seed phrase?

Only while you still have access to the wallet itself. If both the phrase and the wallet are lost, nobody can recover the funds [6]. NIST explains why: a lost private key cannot be regenerated, because doing so is computationally infeasible [7].

Is 12 words enough?

Yes, if the wallet generated them. Twelve words carry 128 bits of randomness, far beyond what anyone can guess [1]. How you store the words matters more than how many there are.

Sources#

Grade A = primary source (regulator, protocol specification, client code, original author). Grade B = expert secondary source used for explanation only.

  1. ABitcoin Improvement Proposals (GitHub). BIP 39: Mnemonic code for generating deterministic keys, 2013.
  2. Aethereum.org. Ethereum security and scam prevention, 2026.
  3. ABitcoin Improvement Proposals (GitHub). BIP 32: Hierarchical Deterministic Wallets, 2012.
  4. ABitcoin.org. Securing your wallet, 2026.
  5. Aethereum.org. Ethereum wallets, 2026.
  6. ABitcoin.org. Some things you need to know, 2026.
  7. AU.S. National Institute of Standards and Technology. NISTIR 8202: Blockchain Technology Overview, 2018. Section 3.4.1, Private Key Storage