Blockchain fundamentals
Gas: resource usage and transaction price
The units consumed and the price paid per unit explain different parts of an execution fee.
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In this article
Metering execution
Ethereum uses gas to measure computational work. A transaction's gas limit bounds the work it is allowed to consume. Fee parameters determine how much the sender is willing to pay under the applicable fee rules.
A high gas limit is not identical to gas actually used. Similarly, a quoted maximum fee is not necessarily the final effective price. Inspect the receipt when calculating costs from completed transactions.
What failure can cost
Execution that reverts can still consume gas. The protocol performed work even though the requested application changes were not committed. A user assessing strategy performance needs to include failed transactions as well as successful trades.
Keep network execution fees separate from a platform's interface fee, swap fees and price impact. Those costs can be collected differently and cannot be reconstructed from one displayed number. This distinction matters when comparing a leader's PnL with a follower's results. See execution prices and copy-trading research.