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Is there a maximum size for any given transaction?

I just created this tx:

http://blockexplorer.com/testnet/tx/194173dcc07b396433d5725abe76d52b10d42ebd3d1d10b465429f87fee12a52

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?

Community
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Doug Peters
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1 Answers1

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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)
Matthieu
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  • Thanks for you answer. Could you please prompt me to the documentation (or source code) of the 200 signature validations limit? – Doug Peters May 12 '14 at 18:33
  • My bad, there is no such transaction checksig limit. It's at the block level. Updated my answer. – Matthieu May 12 '14 at 18:51
  • links are 404 and reedirect. First should probably be something like [this](https://github.com/bitcoin/bitcoin/blob/5961b23898ee7c0af2626c46d5d70e80136578d3/src/validation.cpp#L712) now but more digging needed. Second might be around [here](https://github.com/bitcoin/bitcoin/blob/5961b23898ee7c0af2626c46d5d70e80136578d3/src/policy/policy.cpp#L28). Fees are more dynamic now. Wouldn't put an aboslute value but rather [this](https://jochen-hoenicke.de/queue/#24h). – Giszmo Jan 08 '18 at 14:37