Is extranonce ever necessary to find a block, e.g., in cases where exhausting the regular nonce range fails to block? Is this the rationale behind extranonce?

  • 1
    I don't think "blocking" is a term ever used for "creating blocks".
    – Jannes
    May 19, 2015 at 8:20
  • @Jannes I've seen it used that way before, but I don't know how established that terminology is.
    – Geremia
    May 20, 2015 at 4:17

1 Answer 1


Yes, it's almost always necessary. The current Bitcoin difficulty is 48,807,487,245, which means (approximately) that if you go through all possible values for the regular 32-bit nonce, your probability of finding a valid proof of work is only 1 in 48,807,487,245. So the vast majority of times, you will exhaust all possibilities for the regular nonce, at which point you can increment the extraNonce and continue.

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