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Gas Fee
Gas fee is the fee paid by the sender for computation and recording a transaction on a blockchain. On Ethereum, it goes to validators and is partly burned.
Gas fee is the payment for processing an operation on a blockchain. Any token transfer, smart contract call, DEX swap, or NFT mint requires the network's computing resources, and the user pays for them in the network's native coin (ETH for Ethereum, and also ETH for most EVM-compatible networks, with caveats about their native token).
## How it works
The cost of a transaction is calculated as gas used multiplied by gas price. The price unit is usually measured in gwei, which is one billionth of an ETH. After Ethereum moved to the EIP-1559 model, the price consists of a base fee, which is burned, and a priority fee (tip), which goes to the validator. The gas limit sets the maximum the user is willing to spend; any unused portion is refunded.
## Where it appears
Gas exists on networks that run smart contracts: Ethereum, BNB Chain, Polygon, Arbitrum, Optimism, and Solana (which has its own model, but a similar principle). On Bitcoin, a similar fee is charged based on transaction size in bytes, and the term 'gas' is used loosely. For arbitrage, airdrop farming, and DeFi activity, gas is an expense that must be factored into the economics of a deal.
## What affects it
Network load, the complexity of the operation, and the type of contract determine the final price. For small transfers, the fee can be comparable to the amount sent or even exceed it, so the choice of network and timing directly affects the outcome. Layer-2 solutions reduce costs through batch processing and by posting data to the main network.
## Common mistakes
Not accounting for gas when calculating profit, sending tokens on a network that does not match the wallet or exchange network, and having no native token balance to pay the fee. A failed transaction (revert) also consumes gas, so the fee is not returned after an error. Setting the gas limit too low leads to the same loss.
FAQ
Why is gas sometimes so expensive?
Costs rise when network load is high and many users send transactions at the same time. Complex contracts also require more gas.
What happens to the gas if a transaction fails?
The fee for the computation used is still charged even if execution fails. It usually cannot be refunded.
How does gas limit differ from gas price?
Gas limit is the maximum number of computation units the user allows to be spent. Gas price is the cost of one unit; the total fee equals their product based on the gas actually used.