2 options for Ethereum addresses which have checksums are ICAP and EIP55. Are there others?

For each option, how strong are the checksums? What is the chance that a typing mistake (or mistakes) will still lead to a valid Ethereum address?

  • EIP issue #55 is no EIP at all (yet?).
    – q9f
    Feb 26, 2016 at 8:24
  • Oh, didn't realize so many EIP55 comments added in the past week.
    – eth
    Feb 26, 2016 at 18:19

1 Answer 1



For each address, there is a 1 / 146,150,163 chance that it will not contain any alpha characters and thus cannot be checksummed. On average, an address will have 15 alpha characters which results in 15 bits of checksum data. This means that on average an address that passes the checksum has roughly a 1 / 32,768 or 1 / 2^15 chance of being a false positive.

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