Chapter 2 · Mechanics · lesson 7
Base fee and tip
8 min
Builds on The life of a transaction
Chapter 2 · Mechanics · lesson 7
8 min
Builds on The life of a transaction
Gas measures how much work. This lesson is about what that work costs, which is a separate question with a much stranger answer.
Your fee is:
gas used × (base fee + priority fee)
Blocks target being half full. After a block that ran over half, the base fee rises. After one that ran under, it falls. The adjustment is capped at 12.5% per block, so it moves fast but not instantly.
Crucially, the base fee is burned — destroyed, not paid to anyone.
Burning looks wasteful until you ask the alternative. If validators received the base fee, they would have every reason to stuff blocks with their own fake transactions to drive it up, then collect it back.
Burning removes that incentive completely. The fee has to go somewhere nobody benefits from, and nowhere is the only such place.
On top of the base fee you add a tip, which does go to the validator. That is the part you compete on when you want to go first.
Most of the time the tip is small. When something is being minted, or a large liquidation is available, tips spike to absurd levels for a few blocks.
Predict
Three failure modes, and the fix differs for each:
That third one catches people repeatedly. Your transactions form a queue you cannot reorder.
Check