What is gas fees: the short definition
A gas fee is the fee a user pays, in the network's native coin, to have a transaction or smart-contract action processed and recorded on Ethereum or a similar blockchain.
"Gas" is the unit that measures how much computing work an action needs. A plain coin transfer needs little gas. A token swap or a DeFi contract call needs more.
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The precise definition
On Ethereum, the fee for a transaction is:
gas used × (base fee + priority fee)
- Gas used: the units of work the transaction actually consumed.
- Base fee: a price per unit of gas set by the protocol for each block. It rises when blocks are full and falls when they are not. The base fee is burned (removed from supply), not paid to anyone.
- Priority fee (tip): an extra amount per unit of gas that goes to the validator who includes the transaction.
- Gas limit: the maximum gas the sender allows the transaction to use. It caps the total fee.
- Gwei: the small denomination of ether in which gas prices are usually quoted.
Worked example (hypothetical)
Say you send a token from your crypto wallet. Before you confirm, the wallet shows an estimated gas amount for the action, the current base fee and a suggested tip.
- The wallet multiplies the estimated gas by the base fee plus tip.
- It converts the result from gwei into ETH and shows it next to your transfer.
- After the transaction is mined, the actual fee is the gas really used times the price paid. If the transaction used less gas than the limit, you are not charged for the unused part.
If the network gets busy before you confirm, the base fee goes up and so does the total. The same transfer can cost much more at a busy hour than at a quiet one.
Edge cases experienced users meet
- Failed transactions still cost gas. If a contract call reverts, the work done up to that point is paid for.
- Out of gas. If the gas limit is set too low, the transaction fails and the gas it used is spent.
- Fees are paid in the native coin. Sending a token on Ethereum still requires ETH in the wallet to pay gas. Other compatible networks use their own coin.
- Rollup and sidechain networks usually charge lower gas fees, but they add their own bridging steps and risks.
- Exchange withdrawal fees are set by the exchange. They may not match the live gas price.
Where the term appears
- Wallet confirmation screens: "network fee", "max fee", "priority fee".
- Block explorers: fields such as "Gas Used", "Gas Price", "Gas Limit" and "Transaction Fee" for each transaction.
- News and research: reports of "gas spikes" during busy periods, such as popular token launches or sharp market moves.
On-chain gas fees do not apply when you trade crypto CFDs. CFDs are price contracts with a broker, and their costs are the spread, commission and swap. Leveraged CFD trading on volatile crypto prices can lose money fast.
Related terms
Frequent questions
What does gas fees mean in simple words?
It is the fee you pay the network to process your transaction. More complex actions and busier periods mean a higher fee.
Who receives the Ethereum gas fee?
The base fee is burned. The priority fee goes to the validator who includes your transaction in a block.
Why did I pay a crypto gas fee for a failed transaction?
The network still did the computing work before the transaction failed, and that work is charged.
Can I avoid gas fees?
Not for on-chain transactions. Wallets usually let you change the tip, and fees are lower when the network is less busy, but some fee is always charged.