What is base fee?

The mandatory per-unit gas price an Ethereum block must pay, set by the protocol from how full recent blocks were and destroyed rather than paid to anyone.

Introduced with EIP-1559, it rises when blocks run above target capacity and falls when they run below, which makes fee estimation far more predictable than the old blind auction. Because it is burned, heavy network usage removes ether from supply.

Before EIP-1559 you guessed a price and hoped. Now the protocol publishes a floor that everyone pays and you add a tip on top. Your total cost is the base fee plus whatever priority fee you add, and the part you control is the smaller part.

How it works

EIP-1559 sets a target gas usage equal to the block gas limit divided by an elasticity multiplier of 2, so the target is half the maximum a block can hold (source: EIP-1559).

After each block the protocol adjusts. A block that used exactly the target leaves the base fee unchanged. A fuller block raises it, an emptier block lowers it, and the change is capped by a base fee maximum change denominator of 8, meaning at most 12.5% per block in either direction (source: EIP-1559).

The base fee is not paid to the block producer. EIP-1559 states that the proposer receives only the priority fee and that the base fee is burned, which is why the specification notes only ether can ever be used to pay for transactions on Ethereum.

You set a maximum fee per gas and a maximum priority fee per gas. You are charged the current base fee plus your priority fee, and anything you authorized above that is not spent, so overpaying your maximum costs nothing.

Example

Illustrative: the base fee is 20 gwei and you add a 2 gwei priority fee on a simple transfer costing 21,000 gas. Total gas price is 22 gwei, so the fee is 21,000 times 22, which is 462,000 gwei, or 0.000462 ETH. Of that, 21,000 times 20, or 0.00042 ETH, is burned and 0.000042 ETH goes to the proposer. If the next several blocks run full, the base fee can rise at most 12.5% per block, so 20 gwei becomes about 22.5, then 25.3, then 28.5.

Why it matters when you buy

The base fee is the floor on what any Ethereum transaction costs, including withdrawing from an exchange to your own wallet. It swings with demand across the day, so the same withdrawal can cost several times more at a busy hour than a quiet one. Watching it before you move funds is the cheapest optimization available. See the gas fees guide and compare withdrawal charges at the fee comparison.

Related terms

• priority fee — the tip that actually reaches the proposer
• eip 1559 — the change that introduced the base fee
• gas — the unit the base fee is priced per
• gwei — the denomination fees are quoted in
• burn — what happens to the base fee
• mempool — where a transaction waits if underpriced

Questions

Why is my fee different from the estimate?

Because the base fee moves between your estimate and the block your transaction lands in. You pay the base fee of the block that includes you, not the one you saw when you signed.

Where does the burned ether go?

Nowhere. It is destroyed and removed from supply permanently. No participant receives it, which is the design choice that stops proposers manipulating the base fee.

Does this apply on layer 2 networks?

Most Ethereum-compatible layer 2 networks use the same mechanism for their own fees, but their base fees are far lower and they add a separate cost for publishing data to Ethereum.