Is there a maximum size for any given transaction?

I just created this tx:


and although it seems to get confirmed I would like to know if adding more inputs or outputs (and thus increasing its size) could result in an undesired outcome.

Similar question (that doesn't answer my question, though): What is the maximum size of a transaction?

1 Answer 1


There is a maximum standard transaction size since Bitcoin 0.8.2 of 100k per transaction.

There are a number of other limits that influence the validation and propagation of a transaction though. Specifically:

  • A block is limited to 20000 signature verifications.
  • The block itself can't be larger than 1Mb.
  • The standard Bitcoin client (Bitcoin Core / bitcoind) will refuse to relay transactions flagged as dust.
  • Enough fee should be included (0.0001 BTC/kb)
  • Thanks for you answer. Could you please prompt me to the documentation (or source code) of the 200 signature validations limit? Commented May 12, 2014 at 18:33
  • My bad, there is no such transaction checksig limit. It's at the block level. Updated my answer.
    – Matthieu
    Commented May 12, 2014 at 18:51
  • links are 404 and reedirect. First should probably be something like this now but more digging needed. Second might be around here. Fees are more dynamic now. Wouldn't put an aboslute value but rather this.
    – Giszmo
    Commented Jan 8, 2018 at 14:37

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