I am working on a crypto wallet which supports both Bitcoin and Monero. Wallet first generates a BIP-39 mnemonic and after that mnemonic is used to generate a public and a secret key for Bitcoin.

I want a similar thing for Monero but using the same Mnemonic which is of 12 words. I know how to generate wallets keys and address from 13-word Mnemonic using mymonero-core-cpp code.

So in short my question is that "Is there a way to convert the BIP-39 12 words mnemonic to 13 words mnemonic by appending the checksum or whatever Monero uses in its protocol"?

  • I do believe that Monero uses a 25 word seeds, last one being a checksum. Also not sure i'd want a single seed for all my different coins.
    – Dave
    Jan 4, 2019 at 17:41

1 Answer 1


Assuming your wordlists match, the 13th word is just a checksum word. You concatenate the prefixes of the main 12 words, run a checksum over it, mod that with the word count and, hey presto, you have the index of the word to use as your 13th word.

Example from luigi1111 here which shows creating the checksum

Note that the official Monero wallets makes use of 25 word versions nowadays as these offer much higher entropy.

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