Gas Fee
What is gas?
Gas refers to the unit that measures the amount of computational effort required to execute specific operations on the Ethereum network.
Since each Ethereum transaction requires computational resources to execute, those resources have to be paid for to ensure Ethereum is not vulnerable to spam and cannot get stuck in infinite computational loops. Payment for computation is made in the form of a gas fee.
The gas fee is the amount of gas used to do some operation, multiplied by the cost per unit gas. The fee is paid regardless of whether a transaction succeeds or fails.
How are gas fee calculated?
You can set the amount of gas you are willing to pay when you submit a transaction. By offering a certain amount of gas, you are bidding for your transaction to be included in the next block. If you offer too little, validators are less likely to choose your transaction for inclusion, meaning your transaction may execute late or not at all. If you offer too much, you might waste some ETH. So, how can you tell how much to pay?
The total gas you pay is divided into two components: the base fee and the priority fee (tip).
The base fee is set by the protocol - you have to pay at least this amount for your transaction to be considered valid. The priority fee is a tip that you add to the base fee to make your transaction attractive to validators so that they choose it for inclusion in the next block.
A transaction that only pays the base fee is technically valid but unlikely to be included because it offers no incentive to the validators to choose it over any other transaction. The 'correct' priority fee is determined by the network usage at the time you send your transaction - if there is a lot of demand then you might have to set your priority fee higher, but when there is less demand you can pay less.
For example, let's say Jordan has to pay Taylor 1 ETH. An ETH transfer requires 21,000 units of gas, and the base fee is 10 gwei. Jordan includes a tip of 2 gwei.
The total fee would now be equal to:
units of gas used * (base fee + priority fee)
where the base fee is a value set by the protocol and the priority fee is a value set by the user as a tip to the validator.
i.e. 21,000 * (10 + 2) = 252,000 gwei (0.000252 ETH).
When Jordan sends the money, 1.000252 ETH will be deducted from Jordan's account. Taylor will be credited 1.0000 ETH. The validator receives the tip of 0.000042 ETH. The base fee of 0.00021 ETH is burned.