What is Gas Fee?

On the Ethereum network, every operation — from a simple token transfer to executing a complex smart contract — requires a measurable amount of computational work. Gas is the unit that measures that work. Users pay a fee denominated in ETH to compensate the validators who process and include their transaction in a block.

Gas fees are determined by two factors:

• Gas units required: A fixed amount determined by the complexity of the operation. A standard ETH transfer costs 21,000 gas; interacting with a complex DeFi contract may cost hundreds of thousands of gas.
• Gas price: The amount of ETH (denominated in a sub-unit called gwei) a user is willing to pay per unit of gas. This is set by the user and fluctuates based on network demand.

After Ethereum’s EIP-1559 upgrade in 2021, the fee mechanism changed. Each block now has a base fee — automatically calculated by the protocol based on network congestion — which is burned (destroyed). Users can add an optional priority fee (tip) to incentivize faster inclusion by validators.

Gas fees rise significantly during periods of high network activity, such as NFT launches or volatile market conditions, and fall during quieter periods. High fees have been a major driver of user migration to Layer 2 networks, which process transactions off the Ethereum main chain at a fraction of the cost.

Other blockchain networks use similar fee mechanisms with different names and pricing structures.