BIP39.ai
Online · runs in your browserOnline

Tools on this site compute in your browser. Nothing you type is sent to a server, stored, or put in the URL.

To check this yourself, open your browser’s developer tools → Network, use a tool, and confirm no request is made.

A website can still be changed by whoever controls the server. For a real recovery phrase, use the verified offline file.

BIP39 Converter

Convert test data between entropy, mnemonic and seed. Pick a direction, load a test vector or paste your own test data.

Conversion

Entropy to mnemonic

Encode 128–256 bits of hex entropy (32, 40, 48, 56 or 64 hex characters) as BIP39 words.

Sensitive input

Use test data only. For a real recovery phrase, use the offline tool.Keep this device disconnected while entering a real phrase. Close the browser when done.

Entropy, mnemonic and seed

ValueSizeHow it’s madeReversible?
Entropy128–256 bitsRandom bits—
Mnemonic12–24 wordsEntropy + SHA-256 checksum, split into 11-bit word indexesYes, back to entropy
Seed512 bitsPBKDF2-HMAC-SHA512(mnemonic, "mnemonic" + passphrase, 2048 iterations)No

How to use the converter

  1. Choose a direction with the tabs at the top of the tool.
  2. Enter test data or press Load test vector to use official vector #1.
  3. Press Convert (or Derive seed). Errors explain which part of the input is wrong.
  4. Switching tabs or pressing Clear empties that mode’s input and output.

What this converter does not do

  • It does not derive private keys, extended keys (xprv) or addresses.
  • It does not check balances or connect to any blockchain or API.
  • It does not recover missing words or guess passphrases.

BIP39 ends at the seed. How a wallet turns the seed into keys is defined by other standards such as BIP32 and BIP44.

Frequently asked questions

Why doesn’t the converter show private keys or addresses?

Keys and addresses come from BIP32/BIP44-style derivation applied to the seed, which is a separate standard. Showing them would turn a learning tool into a wallet recovery tool. This page stops at the BIP39 seed.

Is the seed the same as the entropy?

No. Entropy is the 128–256 random bits the words encode. The seed is a 512-bit value produced by running the mnemonic and passphrase through PBKDF2-HMAC-SHA512 with 2048 iterations. You can get from entropy to mnemonic and back, but you cannot recover the mnemonic from the seed.

Why does the same mnemonic give a different seed?

Because of the passphrase. Every passphrase — including an empty one — produces a different, valid seed. See how BIP39 passphrases work.

Can I link directly to one conversion?

Yes: #entropy-to-mnemonic, #mnemonic-to-entropy and #mnemonic-to-seed. Your input is never put in the link.

BIP39 Passphrase

See how an optional passphrase changes the seed.

BIP39 Checksum

Follow each step from entropy to the final checksum word.

BIP39 Generator

Generate 12–24 word test mnemonics and see their entropy and checksum.

Offline Tool

Download the standalone HTML and run it without a network.