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What is gas in crypto?
Gas is the unit that measures how much computing work an operation takes on Ethereum and similar networks. You pay for it in the network's coin: a base fee that is burned, plus an optional tip to the validator who includes your transaction. A plain ETH transfer uses 21,000 gas.
What it means for you
The fee depends on how busy the network is at the moment you send, not on the amount you move, so a small transfer can cost as much as a large one. If a transaction runs out of gas it fails and the gas already used is still charged.
A common mistake: “Sending more ETH costs more gas.”
In fact: Gas measures computation, not value. A plain transfer uses 21,000 gas whether it moves a tiny amount or a large one; the fee changes with the base fee and tip at the moment you send.
How it works
Every operation the network runs consumes gas according to the computing work it takes, and each transaction sets a gas limit, the most units it may use; a standard ETH transfer needs 21,000. The fee is gas used times the base fee plus the priority fee. The protocol sets the base fee, burns it, and moves it by at most 12.5% per block depending on demand. The sender also sets a max fee and is refunded the difference between it and base fee plus tip. If the limit runs out, the changes are reverted but the gas is still consumed.
An example
Say the base fee is 10 gwei and you add a 2 gwei tip to a plain transfer: 21,000 x (10 + 2) = 252,000 gwei, or 0.000252 ETH. If you had set a max fee of 20 gwei, the unused 8 gwei per unit is refunded, not charged.
Source: ethereum.org: Gas and fees · checked 4 October 2026
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