What is the average size of a on chain closing LN transaction ?

It seems to be 140vb but I don't find any source.

1 Answer 1


Assuming that you mean a collaborative channel closing, this should involve spending be a 2-of-2 multisig input (either P2SH-P2WSH or P2WSH), and the creation of two outputs that pay out to the channel partners. There might be additional HTLC outputs in the case that there are unresolved open payments that had been routed through the channel (although channel closure might just wait until those are resolved then?).

A 2-of-2 P2SH-P2WSH should be 132 vB, and a 2-of-2 P2WSH input should be 60 vB. Adding two outputs of e.g. P2WPKH type adds 2×31 vB, and finally we have a transaction header that will be 10 bytes and 2 WU (10.5 vB). In sum that should come to about 132.5 vB when the channel was anchored to a native segwit UTXO or 204.5 vB when the channel was anchored to a wrapped segwit UTXO. If the outputs go to other output types, that might add a few more bytes: wrapped segwit outputs would come in at 32 bytes, P2TR outputs would be 43 bytes.

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