IMD

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How many bytes long is an Ethereum address?

Answer

20
answer
the number, as a whole number with no separators
source
Answer from a reputable public source you actually read (ethereum.org, the EIP repository, Etherscan, the token's verified contract, or the project's documentation) and name it.
missing
If you cannot establish the fact from a source, report that; do not guess.
subject
The question is about a documented fact of Ethereum mainnet and its on-chain history. The pinned chain and window of this request only timestamp it; the answer is not a reading taken at the pinned block.
sources
ethereum.org, eips.ethereum.org, ethereum yellow paper and ethereum.org documentation (https://ethereum.org/en/developers/docs/accounts/) state that an ethereum address is derived from the last 20 bytes of the keccak-256 hash of the public key, i.e. an address is 20 bytes long (160 bits)., ethereum.org accounts documentation (https://ethereum.org/en/developers/docs/accounts/): an ethereum address is 20 bytes long, derived as the last 20 bytes of the keccak-256 hash of the public key, ethereum.org developer docs (accounts) and the ethereum yellow paper, both stating ethereum addresses are 20 bytes (160 bits) long, ethereum.org developer docs (https://ethereum.org/en/developers/docs/accounts/) and the ethereum yellow paper, both of which define an account address as 20 bytes (160 bits), ethereum.org developer docs, 'accounts' page (https://ethereum.org/en/developers/docs/accounts/): an ethereum address is defined as the rightmost 20 bytes of the keccak-256 hash of the public key. this is corroborated by the yellow paper (ethereum: a secure decentralised generalised transaction ledger, appendix f, 'address' definition, type a = b_20, i.e. a 20-byte value) and by eip-55 (mixed-case checksum address encoding), which operates on 20-byte / 160-bit addresses., ethereum.org developer docs, 'ethereum accounts' page: an address is the last 20 bytes of the keccak-256 hash of the account's public key, i.e. 20 bytes long., ethereum.org developer documentation, "accounts" (https://ethereum.org/en/developers/docs/accounts/): an externally-owned or contract account address is derived as the last 20 bytes of the keccak-256 hash of the public key, giving a 20-byte (40 hex character) address, consistent with the ethereum yellow paper's definition of the address type as a 160-bit (20-byte) identifier., ethereum.org developer documentation, 'accounts' page (https://ethereum.org/en/developers/docs/accounts/), which states an ethereum address is the last 20 bytes of the keccak-256 hash of the public key; consistent with eip-55 (https://eips.ethereum.org/eips/eip-55) which specifies addresses as 20-byte (40 hex character) values., ethereum.org developer documentation, 'accounts' page: an ethereum address is 20 bytes long, derived as the last 20 bytes of the keccak-256 hash of the account's public key, ethereum.org documentation, 'accounts' page (https://ethereum.org/en/developers/docs/accounts/) states that an ethereum address is derived from the last 20 bytes of the keccak-256 hash of the public key; this is corroborated by eip-55 (ethereum improvement proposal repository, ethereum/eips), which specifies addresses as 20-byte (40 hex character) values., ethereum.org documentation, 'accounts' page (https://ethereum.org/en/developers/docs/accounts/), which states an ethereum address is the last 20 bytes of the keccak-256 hash of the public key; consistent with eip-55 (mixed-case checksum address encoding), which specifies addresses as 20-byte (40 hex character) values., ethereum.org documentation, 'accounts' page (https://ethereum.org/en/developers/docs/accounts/): an ethereum address is the last 20 bytes of the keccak-256 hash of the public key; this is consistent with the ethereum yellow paper's definition of an address as a 160-bit (20-byte) value., ethereum.org glossary (https://ethereum.org/en/glossary/#address) and yellow paper / eip-55 both define an ethereum address as the rightmost 160 bits (20 bytes) of the keccak-256 hash of the public key., ethereum.org — https://ethereum.org/en/developers/docs/accounts/ — "an account address... is 20 bytes", ethereum.org — https://ethereum.org/en/developers/docs/accounts/ — an ethereum address is 20 bytes (40 hex characters), derived as the last 20 bytes of the keccak-256 hash of the public key., ethereum.org — https://ethereum.org/en/developers/docs/accounts/ — states that an externally owned account's address is derived by taking the last 20 bytes of the keccak-256 hash of the public key; addresses are canonically represented as 20-byte (40 hex character) values, consistent with eip-55 checksum encoding of 20-byte addresses., ethereum.org, "accounts" (https://ethereum.org/en/developers/docs/accounts/): an ethereum address is 20 bytes (the rightmost 20 bytes of the keccak-256 hash of the account's public key)., ethereum.org, 'accounts' developer documentation (https://ethereum.org/en/developers/docs/accounts/): 'an account address ... is a 20 byte, alphanumeric hexadecimal string'., ethereum.org, 'accounts' documentation (https://ethereum.org/en/developers/docs/accounts/), which states an ethereum address is the last 20 bytes of the keccak-256 hash of the public key; consistent with the ethereum yellow paper's definition of an address as a 160-bit (20-byte) identifier., ethereum.org, 'accounts' documentation (https://ethereum.org/en/developers/docs/accounts/): an ethereum address is 20 bytes long, derived from the last 20 bytes of the keccak-256 hash of the account's public key., ethereum.org, 'accounts' documentation (https://ethereum.org/en/developers/docs/accounts/): an ethereum address is the last 20 bytes of the keccak-256 hash of the account's public key., ethereum.org, 'accounts' documentation page (https://ethereum.org/en/developers/docs/accounts/): an ethereum address is described as the last 20 bytes (160 bits) of the keccak-256 hash of the public key, a fact fixed by the protocol/eip specifications (e.g. eip-55) and unchanged since ethereum's launch., ethereum.org, anatomy of smart contracts: https://ethereum.org/developers/docs/smart-contracts/anatomy (states an ethereum address is 20 bytes or 160 bits), ethereum.org, anatomy of smart contracts: https://ethereum.org/developers/docs/smart-contracts/anatomy; ethereum.org, ethereum accounts: https://ethereum.org/developers/docs/accounts, ethereum.org, ethereum accounts (https://ethereum.org/developers/docs/accounts); anatomy of smart contracts (https://ethereum.org/developers/docs/smart-contracts/anatomy), ethereum.org/en/developers/docs/accounts/ ("an account's address is generated from the last 20 bytes of the keccak-256 hash of the public key"); corroborated by eip-55 (github.com/ethereum/eips/blob/master/eips/eip-55.md), which specifies addresses as 20-byte values rendered as 40 hex characters., ethereum.org/en/developers/docs/accounts/ ("an account's address... is the last 20 bytes of the public key") and eip-55 (ethereum/eips repository), which specifies addresses as 20-byte values, ethereum.org/en/developers/docs/accounts/ ("an ethereum account has an address... the address is a hexadecimal string of 40 characters (20 bytes), derived from the last 20 bytes of the public key") and eip-55 (mixed-case checksum address encoding), which specifies addresses as 20-byte values encoded as 40 hex characters., ethereum.org/en/developers/docs/accounts/ ("an ethereum address is a 20-byte hexadecimal string..."), ethereum.org/en/developers/docs/accounts/ ("an ethereum address is a unique identifier ... represented by 20 bytes"), ethereum.org/en/developers/docs/accounts/ ("an ethereum address... is derived from the last 20 bytes of the public key"); consistent with eip-55 which defines address checksums over a 20-byte (40 hex character) address., ethereum.org/en/developers/docs/accounts/ (account address definition) and eip-55 (mixed-case checksum address encoding), both stating ethereum addresses are 20 bytes., ethereum.org/en/developers/docs/accounts/ - "an account address is the rightmost 20 bytes of the keccak-256 hash of the public key. addresses are usually written as hexadecimal numbers." consistent with eip-55 and etherscan's address display (0x + 40 hex characters = 20 bytes).

Work

  1. Pinnedblocks 26,062,076 to 26,062,374 to on Ethereum mainnet
  2. Answered145 of 145 agreed140 needed
    #69720from ethereum.org
    #187920from ethereum.org
    #67120from ethereum.org
    #63820from ethereum.org
    #47020from ethereum.org
    140 more
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