What is Ethereum gas?

Gas is the unit that measures how much work an Ethereum transaction does. Adding two numbers costs a few units and writing to storage costs thousands, and the fee you pay is the gas your transaction consumed multiplied by the price you agreed to pay per unit.

A gwei is one billionth of an ether, or 0.000000001 ETH. Gas prices are quoted in gwei because the numbers are unreadable written out in whole ether, and the name is short for gigawei.

Why do Ethereum gas prices change?

Each block holds a limited amount of gas and has a target set at half that limit. After every block the protocol compares the gas actually used against the target and moves the base fee up or down for the next block, by at most 12.5%, so the price tracks demand for block space.

EIP-1559 is the fee market Ethereum has used since the London upgrade. Every transaction pays a base fee that the protocol sets and burns, plus a priority fee that goes to the block proposer, and the max fee is the ceiling you set on the two together.

How much should you tip on an Ethereum transaction?

The base fee is charged to everyone in the block, so the priority fee is the only number you actually choose. Match it to what recent blocks paid rather than picking a round figure, because overpaying buys position you rarely need and underpaying leaves the transaction pending.

How do you set gas fees in MetaMask?

On the confirmation screen, open the network fee row and choose Advanced to get the editable fields instead of the presets. Set the priority fee to match what recent blocks paid, set the max base fee above the current base fee with room to spare, and leave the gas limit alone.

When is the best time to send an Ethereum transaction?

Activity thins out during the small hours UTC and over weekends, so fees are usually lowest then. The pattern is real but weaker than most advice implies, and event-driven spikes move the price far more than the hour of the day does.

Learn about Ethereum gas

Short guides on what you pay for when you send a transaction, why the price moves, and how to pick a tip yourself instead of taking whatever your wallet suggests.

What is Ethereum gas?
What you are paying for when a transaction costs money.
What is gwei?
The unit gas prices are quoted in, and how it relates to ETH.
Why gas prices change
Block space is limited, so the price of it moves with demand.
EIP-1559 explained
Base fee, priority fee, max fee, and which part gets burned.
How much should you tip?
Picking a priority fee, and what it costs to get it wrong.
How to set gas in MetaMask
Where the custom fee fields are and what each one does.
Best time to transact
Whether waiting for cheap gas is worth it, and how to wait.

For the specification itself, read the Ethereum documentation on gas.

Learn about Ethereum gas

What is Ethereum gas?

What is gwei?

Why gas prices change

EIP-1559 explained

How much should you tip?

How to set gas in MetaMask

Best time to transact