EIP-1559 Gas Fee Planner
Work out what to set for max fee and priority fee under EIP-1559, what you will actually pay, how much is refunded, and how far the base fee can rise before your transaction stalls.
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You are refunded the difference between your max fee and what was needed
EIP-1559 splits the gas price into a base fee that is burned and set by the protocol, and a priority fee that goes to the validator. You specify a maximum you are willing to pay per unit and a priority fee, and you are charged the base fee plus the priority fee, with the remainder of your maximum refunded. Setting a high maximum therefore does not cost more; it only widens the range of base fees at which your transaction can still be included. The common instinct to set the maximum tightly to save money is exactly backwards.
The base fee moves predictably and the priority fee does not
The base fee changes by at most 12.5 percent per block, in a direction determined by whether the previous block was more or less than half full. That makes it forecastable: even a sustained run of full blocks takes several blocks to double it, so a maximum set at twice the current base fee survives roughly six consecutive full blocks. The priority fee is a market for inclusion in the next block specifically, and it is what actually decides whether you are picked up quickly.
A stuck transaction is a max fee problem, not a priority problem
If the base fee rises above your maximum, your transaction cannot be included at any priority fee, because the maximum bounds the total. It sits in the mempool until the base fee falls back or you replace it. Raising the priority fee on a replacement without raising the maximum does nothing, which is why the standard advice to bump the tip fails in exactly the situation people reach for it.
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Frequently Asked Questions
Does a high max fee cost more?
No. You pay the base fee plus your priority fee and the rest is refunded, so a high maximum only widens the range of base fees at which you can still be included.
Why is my transaction stuck?
Usually because the base fee rose above your maximum, at which point no priority fee can get it included because the maximum bounds the total. Raising only the tip on a replacement does nothing.
How fast can the base fee rise?
By at most 12.5 percent per block. A doubling therefore takes about six consecutive full blocks, which makes a maximum set at twice the current base fee reasonably durable.
Where does the base fee go?
It is burned rather than paid to anyone. Only the priority fee reaches the validator, which is why the priority fee is what determines how quickly you are included.
What is a good priority fee?
Enough to beat the transactions competing for the same block. On a quiet chain that is a fraction of a gwei; during contention it is whatever the current market is, and it is the only part that affects your position in the queue.
Privacy & Security
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How to Use
Enter the current base fee and your settings to plan a transaction.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.