Priority Fee Auctions in Practice

The base fee is a floor set by the protocol. The priority fee is a bid, and during congestion it determines whether your transaction is in the next block or the one after several.

What the tip buys

Position in the queue, probabilistically rather than deterministically.

Block builders assemble the most valuable block they can. Your tip is one input into that calculation, alongside any value available from ordering transactions in a particular way.

A higher tip improves your odds. It does not guarantee placement, because the builder is optimising the whole block rather than ranking by tip alone.

When the tip matters

During congestion. When more transactions want inclusion than fit, the tip is the differentiator.

For time-sensitive operations. A liquidation, an arbitrage, a mint with limited supply.

When a transaction must land before a deadline. A slippage-sensitive swap where waiting means a worse price.

When it does not

During quiet periods. The base fee is the binding constraint and inclusion in the next block or two is near-certain regardless of tip.

Most users, most of the time, are in this situation. Paying for a fast tier during a quiet hour buys nothing.

The speed tiers in wallets

Wallets present fast, average and slow options. These adjust the priority fee and not the base fee.

That means the difference between tiers is smaller than it appears when the base fee dominates the total, which is most of the time. During congestion the tiers separate meaningfully.

Checking the base fee before selecting a tier tells you whether the choice matters.

The failed-bid problem

A transaction submitted with an insufficient tip during congestion sits pending. It is not lost; it waits, and it confirms when conditions ease or when it is replaced.

Replacing costs the new fee and not both. Waiting costs nothing.

For anything not urgent, waiting is almost always correct, and the base fee falls whenever blocks are less than half full.

Watching the auction

Mempool visualisation tools show the pending set by fee level and estimate what the next blocks will contain.

That display tells you directly whether your intended tip will be included, which is more useful than any estimate derived from recent averages.

The user who never encounters this

Anyone whose activity is buying on a venue and withdrawing periodically.

Purchases are matched internally with no auction involved. Withdrawals have their fee set by the platform, and venues that show the network component separately, such as venues that quote the network fee separately, let you see what is being bid on your behalf without participating in the auction yourself.