I am reading the bitcoin developer reference and having a look on the transaction input structure. If you have a look here https://bitcoin.org/en/developer-reference#raw-transaction-format it says that the previous output has 36 bytes. I am confused, because I read also the 'Mastering Bitcoin Book' and this wiki page (https://en.bitcoin.it/wiki/Transaction) and they state that the size is 32 bytes.

Is this a mistake in the reference or is it something new which did not propagate to the other sites? Would be nice if someone could clear that up for me :)

1 Answer 1


It is because in the developer guide they are referring to the outpoint, not the output. The outpoint is a data structure used to refer a particular output, that consists of:

outpoint = txid(32 bytes) + output index (4 bytes)
  • No problem. Hope it helps.
    – sr_gi
    Feb 23, 2017 at 23:03
  • It does. I would like to set this as answered but have to wait a couple more minutes.
    – Donut
    Feb 23, 2017 at 23:04

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