Gas, honestly
Not a metaphor about fuel — a working model of what the fee is, why it moves, why a failed transaction still costs money, and what actually changes on a rollup.
Gas is explained with a fuel metaphor that gets one thing right and everything else wrong. Here is the model that actually predicts what you will pay.
Two numbers, multiplied
Every fee is work × price.
Work is measured in gas units and is a property of what you are doing. A plain transfer is 21,000 units. A token transfer is more. A mint that writes several storage slots is more again. This number barely changes over time — it is determined by the operations the contract performs, not by how busy the network is.
Price is what you pay per unit, and it is the part that swings. It has two components:
- The base fee is set by the protocol, not by you. It adjusts automatically block by block: if the last block was more than half full, it rises; if less, it falls. It is burned rather than paid to anyone. It can only move about 12.5% per block, which is why congestion ramps rather than spikes instantly — and why it also takes several blocks to come back down.
- The priority fee is your tip to the block producer, and it is the only part you are really bidding with. When blocks are full, the tip decides the queue.
Your wallet also asks for a max fee, which is a ceiling, not a payment. You pay base plus tip; the ceiling only determines whether your transaction is eligible while the base fee is high. Setting a generous ceiling does not cost you more — it prevents your transaction from being stranded if the base fee rises after you sign.
Why a mint spikes it
A popular mint asks a few thousand people to send transactions inside the same minute. Blocks fill, the base fee ratchets up 12.5% at a time, and everyone who wants to be in the next block raises their tip against everyone else doing the same thing.
Two consequences follow directly, and both catch people out:
The mint is not the only thing that got expensive. The base fee is network-wide. A swap you make during someone else's mint costs more for reasons that have nothing to do with you.
A "free" mint is not free. The item costs nothing; the transaction never does. During contention the fee can exceed what the item is worth by a wide margin, which is the most reliable way a launch turns enthusiasm into resentment.
Why a failed transaction still costs money
This is the single most confusing part of the model, and it follows from what you are paying for.
You are not paying for a result. You are paying validators to execute your instructions. If execution runs and then hits a condition that reverts it — the supply sold out, the allowlist rejected you, the price moved past your limit — the work was still done. You pay for the work up to the revert, and the state change is discarded.
Running out of gas is the same story with a worse ending: the limit you set was too low, execution stopped partway, everything is rolled back, and the entire limit is consumed.
This is why competitive mints are expensive to lose. Five hundred people paying to be told the supply is gone is not a bug in the system; it is what the system charges for.
What a rollup actually changes
Fees on an L2 are typically one to three orders of magnitude lower, and it is worth knowing why, because it tells you when they will not be.
A rollup executes your transaction on its own chain, cheaply, and then posts data back to Ethereum so the result can be verified. Your fee has two parts: a small execution cost on the rollup, and your share of the cost of posting that data to L1.
The second part is the one that moves. When Ethereum is expensive, the data cost rises and rollup fees follow — the correlation is loose and delayed, but it is there. Dedicated data space for rollups made this much cheaper and much steadier than it used to be, but it did not sever the link.
The practical version: L2 fees are low and fairly stable, and they are not fixed. Read them before a mint rather than assuming.
Five habits
- Check the base fee before signing anything optional. A gas tracker takes five seconds and most non-urgent transactions can wait an hour.
- Raise the max fee, not the tip, to avoid being stranded. They do different jobs.
- Treat the wallet's simulation as the useful part of the confirmation screen. If it says the transaction will fail, it is usually right, and signing anyway costs real money to be told so again.
- For a contested mint, decide your total in advance. Item price plus worst-case fee. If that number is not worth it, not minting is a position.
- Do not raise the gas limit to fix a revert. A revert is a rule saying no; more gas just pays more to hear it.
