<p><a href="https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki" rel="nofollow noreferrer">BIP39</a> mnemonics are restricted to encode 128 to 256 bits of entropy corresponding to 12 to 24 words. Since 128 bits of security already appears to be quite enough (see <a href="https://security.stackexchange.com/a/6149/247155">this answer</a> on Information Security StackExchange), a better question might be why it even allows you to go up to 256. However I can't imagine you could need even more than that, because if the cryptography behind mnemonics is so broken in the future that 24 words aren't enough, adding more words probably won't help.</p>
<p>Other than setting reasonable limits, there's nothing in BIP39 preventing you from using any number of words that is a multiple of 3 (including 3 or even 0). You could code your own wallet, or better yet you could modify an existing wallet's source code to remove these limits. However I would advise not to store any actual funds with this mnemonic seed. The standard exists so that a seed can be used with any compatible wallet, and using an incompatible seed defeats that purpose.</p>

CC BY-SA 4.0
2022-06-30T04:16:03.687Z
2022-06-30T04:16:03.687Z
Vojtěch Strnad
<p>Does the math break if you go above 24? Is there a reason its not done?  Can I code my own wallet to have, say, 27 or 48 words?  Would this add to the entropy and difficulty of hacking or would it just be an inconvenience to the user? Are such wallets incompatible with the blockchain?</p>

<mnemonic-seed>
Why arent wallets made to generate more than 24 word recovery phrases?
SquishyRhode
# Why arent wallets made to generate more than 24 word recovery phrases?

(Asked by: username_0 on 2022-06-30)

Does the math break if you go above 24? Is there a reason its not done? Can I code my own wallet to have, say, 27 or 48 words? Would this add to the entropy and difficulty of hacking or would it just be an inconvenience to the user? Are such wallets incompatible with the blockchain?

**Tags:** mnemonic-seed


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## 1 answers

### Answer by username_1 on 2022-06-30. Score: 2

[BIP39](https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki) mnemonics are restricted to encode 128 to 256 bits of entropy corresponding to 12 to 24 words. Since 128 bits of security already appears to be quite enough (see [this answer](https://security.stackexchange.com/a/6149/247155) on Information Security StackExchange), a better question might be why it even allows you to go up to 256. However I can't imagine you could need even more than that, because if the cryptography behind mnemonics is so broken in the future that 24 words aren't enough, adding more words probably won't help.

Other than setting reasonable limits, there's nothing in BIP39 preventing you from using any number of words that is a multiple of 3 (including 3 or even 0). You could code your own wallet, or better yet you could modify an existing wallet's source code to remove these limits. However I would advise not to store any actual funds with this mnemonic seed. The standard exists so that a seed can be used with any compatible wallet, and using an incompatible seed defeats that purpose.


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