Bitcoin and chains · 10 / 86 · 3 min
Accounts, gas, and blocks
A transaction asks the network to do work. Gas is what you pay for that work. A block is a batch of transactions that became part of the history.
Gas is the chain's fee, not a tip to the project. A failed transaction can still cost it.
A worked case
Someone repeats a swap while the chain is busy. The transaction fails because the price moved. The wallet still shows a gas charge. They paid the network for work that did not give them the token.
What you pay
Gas is not a tip to the project you are using. It is the fee for the chain. When the chain is busy, the same click costs more. A failed transaction can still cost gas.
When it is final
Seeing a pending status is not the end. One confirmation is a start. More confirmations mean it is harder to rewrite. An exchange may wait longer than the chain does before it credits you.
Final on the chain is not the same as final in a company's account.
London, 2021: the fee became a rule
Gas is the fee for computation and storage on Ethereum. It is not a tip to the website you clicked. When many people want the same block, the same click costs more. A transaction that fails because a price moved, or a condition was not met, can still have used the computer. The protocol does not refund that. You paid for work, not for a successful wish.
In August 2021 the London upgrade, EIP-1559, changed how the fee is set. A base fee is burned, and a priority tip goes to the validator. Wallets started predicting a total. The prediction can be wrong, and a busy hour still blows through a casual click. None of that made gas a project fee. If a site adds its own charge on top, that is a second bill. Read both.
Finality is a cousin of this. One confirmation is a start. An exchange may wait for more before it credits you, because a shallow block can still be rewritten at a cost. Pending on your phone is not final on the chain, and final on the chain is not the same as final inside a company's account.
Read it yourself
These links are the record. They are not a recommendation, and they are not instructions. A news story or a court paper can still be wrong about a detail. The check does not change because a famous name is in the story.
Apply the check
Open a question. The line is about this topic. It is not a verdict that anything is safe.
Validators or miners, not the app you meant to use.
The fee market, when blocks are full.
You already paid it. A failed transaction does not refund the gas.
Check yourself
If a transaction fails, can it still cost you?
Yes. You can pay gas for a transaction that does not do what you hoped.
After this you can tell a gas fee from a project fee, and wait for finality before you treat a payment as done.