EntropyCheckv1.0 Download offline
BROWSER-LOCAL COMPUTATIONBitcoin only English BIP39

YOUR BITCOIN SEED, EXPLAINED.

Understand the strength
behind your seed.

From recovery words to risk, randomness, and Bitcoin addresses.
A private, browser-local workspace for learning how it all fits together.

No accountsNo data uploadsWorks offline

01 / THE PHRASE

Start with the words.

Paste a test phrase to check it, or explore with a generated example.

Use an existing phrase

0 words

Enter a phrase to check its structure.

English · 12, 15, 18, 21, or 24 words. All calculations happen in this page.

This context is self-reported. The phrase cannot verify its source.

Or generate a test phrase

Creates new words and analyzes them in one step.

What we can tell you

PHRASE ASSESSMENT

Analyze a phrase to see its risk

Waiting for a phrase

Enter words to check their length, wordlist, and checksum.

BIP39 capacityN/A bits
ChecksumN/A bits

Capacity is the encoded entropy length, not a measurement of actual randomness.

Randomness has a backstory.

A valid phrase tells us how many bits it encodes. It doesn’t tell us how unpredictably those bits were chosen.

Entropy details Explore the numbers behind your words →

Every word represents a number.

The English BIP39 list contains 2,048 words, indexed from 0 to 2047. Each index becomes 11 binary digits. Together, those digits encode the entropy and its checksum.

Index 0 = abandon.

The official word list on GitHub ↗ displays lines starting at 1. To find a word there, add 1 to its BIP39 index: index 1477 → line 1478. “Word 1” below means the first word in your phrase, not its wordlist index.

Analyze a valid phrase to see its word indices.

    These numbers and binary digits reveal the same secret as the recovery phrase. Treat them with the same care.

    Entropy

    HEXADECIMAL

    No valid phrase loaded.

    RAW BINARY · ENTROPY BITS ONLY

    No valid phrase loaded.

    Checksum & full encoding

    CHECKSUM BITS · NOT ADDITIONAL ENTROPY

    No valid phrase loaded.

    FULL MNEMONIC BINARY · ENTROPY + CHECKSUM

    No valid phrase loaded.

    Structure checks

    Word count
    Waiting
    English wordlist
    Waiting
    Checksum
    Waiting

    Pattern checks

    These checks recognize a limited set of simple constructions. Passing them cannot certify a generator or establish secrecy. The checksum detects some mistakes; it does not add randomness.

      02 / THE POSSIBILITIES

      What do these words really tell us?

      Three things matter: valid words, random generation, and secrecy.

      01 / STRUCTURE

      Valid doesn’t mean secure.

      The checksum catches some mistakes. It cannot prove randomness.

      02 / RANDOMNESS

      How it was made matters.

      More words help only if they come from secure randomness.

      03 / SECRECY

      Public words aren’t secret.

      A shared or exposed phrase can be tried directly.

      Actual source entropy

      Not analyzed

      A simple analogy

      How hard would it be to guess?

      Conditional estimate

      Average search time

      Analyze a phrase first

      Assumptions and limits

      Estimates need a stated generation or attack model, a known verification target, and a fixed or known passphrase.

      This describes phrase guessing only. Exposure, a predictable generator, malware, partial knowledge, and other attacks can bypass this model. Checksum bits and the derived 512-bit seed do not add randomness.

      Compare other phrase lengths

      Hypothetical comparison only. These figures do not assess the phrase above. They assume uniformly random generation, a fixed or known passphrase, and a known verification target. Checking rates are illustrations, not hardware benchmarks or mining hash rates.

      Compare phrase lengths

      Possible phrases

      3.40 × 10³⁸

      128 random bits

      Average exhaustive search

      5.39 × 10¹⁸ years

      Half the space, on average

      A very long coin flip.

      Imagine guessing the exact outcome of 128 independent, fair coin flips. All of them, in order. That’s the chance of one correct guess.

      One winning ticket.

      A lottery with one winner among 3.40 × 10³⁸ equally likely tickets. Each extra random bit doubles the number of tickets.

      See the exact numbers and assumptions
      Possible phrases · N = 2ᴱᴺᵀ
      Probability of one correct guess
      Average search · (N + 1) / (2R)

      Assumes uniform random generation, no repeated guesses, a fixed or known passphrase, and a known target to verify each candidate. One year is 31,557,600 seconds. Checking rates are illustrations, not measured hardware performance or Bitcoin mining hash rates.

      This models searching for a phrase. It does not measure overall wallet security, other attacks on Bitcoin keys, malware, or exposure. A 512-bit derived seed and checksum bits do not create extra randomness. Unknown or human-chosen generation may have a much smaller search space.

      A real example: a faulty generator

      Milk Sad produced long wallet secrets from just 32 bits of possibilities. The words looked random, but were predictable. Read the disclosure ↗

      03 / THE BITCOIN PATHS

      One seed. Different destinations.

      A derivation path tells a wallet which keys to use. These are common conventions; the words alone don’t identify which path your wallet used.

      Choose an address type above. Path examples show mainnet, account 0, receiving address 0. An apostrophe marks hardened derivation. Testnet uses coin type 1'.

      Case and spaces matter. Every passphrase creates a different wallet; there’s no “incorrect passphrase” error. Unicode is normalized with NFKD.

      Enter a valid phrase above to derive addresses.

      TAKE IT OFFLINE

      Same tool.
      No connection required.

      One HTML file, with everything included. No installation, accounts, or external libraries to load.

      Download offline HTML
      1. Download and verify.Get the file and SHA256SUMS from a trusted release. Compare its SHA-256 hash; rebuild from the pinned source for additional verification.
      2. Move to a trusted, disconnected device.Transfer the verified file to your offline computer. Browser extensions, malware, and operating-system security still matter.
      3. Open it in your browser.Double-click the HTML file. A local-file label does not prove an air gap. Clear the session and close the page when finished; browser memory erasure cannot be guaranteed.
      Standards, dependencies & limitations

      Based on BIP39, BIP32, BIP44, BIP49, BIP84, and BIP86. Statistical tests cannot certify a cryptographic generator: NIST SP 800-22. Checksum validity does not establish randomness or secrecy.

      English BIP39 only. Other formats, including native Electrum and SLIP39 phrases, are not assessed. This tool does not find balances, recover missing words, or sign transactions. It stores no session data and makes no runtime network requests. Following an external link or downloading from the hosted page is an explicit network action.

      Cryptography uses @scure/bip39, @scure/bip32, and @scure/btc-signer. Dependency audit history is not an audit of this application. EntropyCheck has not received an independent security audit.

      Open-source license notices
      EntropyCheck 1.0.0

MIT License

Copyright (c) 2026 EntropyCheck contributors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.


Public BIP39 examples: trezor/python-mnemonic

The MIT License (MIT)

Copyright (c) 2013-2016 Pavol Rusnak

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.


Bundled dependency licenses

@noble/curves@2.4.0
================================================================
The MIT License (MIT)

Copyright (c) 2022 Paul Miller (https://paulmillr.com)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

@noble/hashes@2.4.0
================================================================
The MIT License (MIT)

Copyright (c) 2022 Paul Miller (https://paulmillr.com)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

@scure/base@2.4.0
================================================================
The MIT License (MIT)

Copyright (c) 2022 Paul Miller (https://paulmillr.com)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

@scure/bip32@2.4.0
================================================================
The MIT License (MIT)

Copyright (c) 2022 Patricio Palladino, Paul Miller (paulmillr.com)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

@scure/bip39@2.4.0
================================================================
The MIT License (MIT)

Copyright (c) 2022 Patricio Palladino, Paul Miller (paulmillr.com)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

@scure/btc-signer@2.4.1
================================================================
The MIT License (MIT)

Copyright (c) 2022 Paul Miller (https://paulmillr.com)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

micro-packed@0.11.1
================================================================
The MIT License (MIT)

Copyright (c) 2022 Paul Miller (https://paulmillr.com)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.