You've got some great answers here from gandlaf21 (npub1cj6…86t6), Beerborn (npub16up…nevp), and Sovtoshi (npub19ex…yyr9).
ChatGPT was close, but not quite accurate about the relationship of UTXOs and Lightning transactions. You don't spend any UTXOs when you make Lightning transactions. You just reallocate ownership of the sats WITHIN one or more UTXOs.
When you are transacting on Lightning, the channel you are transacting through IS the UTXO. Every transaction you do is an update to the agreement of HOW that UTXO will eventually be spent, but without actually spending it. Spending the UTXO would involve broadcasting that agreement to the Bitcoin network which closes the channel.
Liquidity is the total amount of available sats within a Lightning channel; the UTXO that you share ownership of with your channel partner in a 2:2 multisig. Inbound and outbound liquidity are referring to the portion of those sats that each channel partner will receive when the UTXO is spent, closing the channel. "Inbound" and "outbound" are a matter of perspective.
For instance, if you and I have a Lightning channel together and you have 500k sats on your side of our channel, you have 500k of outbound liquidity in that channel, and I have 500k of inbound liquidity. It is outbound to you, because 500k is the maximum amount you can send OUT of that channel. It is inbound to me, because 500k is the maximum I can receive through you. So how much inbound liquidity do you have? That depends on how many sats I have on my side of the channel. Let's say I have 750k sats on my side of the channel. That means you have 750k sats of inbound liquidity and I have 750k sats of outbound liquidity.
It's easiest to see it in action by actually running a node with a few channels open and watching as the sats you spend move to your channel partner's side of the channel, becoming incoming liquidity for you, so you can receive them back again later.
Dikaios1517
npub1ku…v3lhe
2025-04-09 16:22:59
in reply to nevent1q…9esx
Author Public Key
npub1kun5628raxpm7usdkj62z2337hr77f3ryrg9cf0vjpyf4jvk9r9smv3lheSeen on
wss://nos.lolPublished at
2025-04-09 16:22:59Event JSON
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"content": "You've got some great answers here from nostr:npub1cj6ndx5akfazux7f0vjl4fyx9k0ulf682p437fe03a9ndwqjm0tqj886t6, nostr:npub16up8472yajrceaxq72yz4an7lggw0s6esgg7rm74k8fh3khsesjs6vnevp, and nostr:npub19ex4k26qhjlnvqdmwzagmhk6epxkz7z5the57n4kthfu0t6g8r8sz5yyr9.\n\nChatGPT was close, but not quite accurate about the relationship of UTXOs and Lightning transactions. You don't spend any UTXOs when you make Lightning transactions. You just reallocate ownership of the sats WITHIN one or more UTXOs.\n\nWhen you are transacting on Lightning, the channel you are transacting through IS the UTXO. Every transaction you do is an update to the agreement of HOW that UTXO will eventually be spent, but without actually spending it. Spending the UTXO would involve broadcasting that agreement to the Bitcoin network which closes the channel.\n\nLiquidity is the total amount of available sats within a Lightning channel; the UTXO that you share ownership of with your channel partner in a 2:2 multisig. Inbound and outbound liquidity are referring to the portion of those sats that each channel partner will receive when the UTXO is spent, closing the channel. \"Inbound\" and \"outbound\" are a matter of perspective.\n\nFor instance, if you and I have a Lightning channel together and you have 500k sats on your side of our channel, you have 500k of outbound liquidity in that channel, and I have 500k of inbound liquidity. It is outbound to you, because 500k is the maximum amount you can send OUT of that channel. It is inbound to me, because 500k is the maximum I can receive through you. So how much inbound liquidity do you have? That depends on how many sats I have on my side of the channel. Let's say I have 750k sats on my side of the channel. That means you have 750k sats of inbound liquidity and I have 750k sats of outbound liquidity.\n\nIt's easiest to see it in action by actually running a node with a few channels open and watching as the sats you spend move to your channel partner's side of the channel, becoming incoming liquidity for you, so you can receive them back again later.",
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