The Extra nonce for the genesis block in bitcoin core is 0x010445, how was this value calculated?

  • An extra nonce is just some random data that's part of the coinbase tx. It isn't really calculated. Jul 24, 2018 at 5:54

1 Answer 1


The extra nonce is just like the normal nonce in a block header. It is "calculated" by using a counter which increments every time all of the possible nonces for the block header nonce field are exhausted. This process of incrementing the nonce and then the extra nonce is repeated until a valid block hash is found.

  • I'm not sure if this still matters since Bitcoind dropped mining, but in the original implementation didn't extra nonce reset to zero when the timestamp changes, but the regular nonce only when it overflows? Jul 24, 2018 at 8:00
  • 1
    The extra nonce actually never reset in the original implementation and would actually continue counting up over multiple blocks. It would only increment on nonce overflows, but it would be reused across blocks. E.g. if a block had been found with an extra nonce of 2, the next block to be mined would start with an extra nonce of 3 instead of 0.
    – Ava Chow
    Jul 24, 2018 at 8:03

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