[Ethereum] How large are the Ethereum block headers

block-headerlight-clients

I am interested in knowing the block header size to estimate the overhead of running an Ethereum light client.

Best Answer

Ok, so according to the Yellow paper (section 4.4), we have several fields in the block header:

  1. parentHash, 256 bits
  2. ommersHash, 256 bits
  3. beneficiary, 160 bits
  4. stateRoot, 256 bits
  5. transactionsRoot, 256 bits
  6. receiptsRoot, 256 bits
  7. logsBloom, 256 bytes (see here)
  8. difficulty, big int scalar
  9. number, big int scalar
  10. gasLimit, big int scalar
  11. gasUsed, big int scalar
  12. timestamp, big int scalar
  13. extraData, (up to) 256 bits
  14. mixHash, 256 bits
  15. nonce, 64 bits

Summing everything up we get:

  1. 256*7+160+64 + 8*256 = 4064 bits (508 bytes)
  2. 5 variable length scalars
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