Gas (Ethereum)

Gas is Ethereum’s unit of computational cost. Every operation the Ethereum Virtual Machine (EVM) can execute — add two numbers, read storage, hash a value, send a transaction — has a defined gas cost. Users pay validators in ETH for that gas, denominated as gas_used × gas_price.

Concrete examples (approximate, post-Cancun upgrade):

• Simple ETH transfer: 21,000 gas (fixed minimum)
• ERC-20 token transfer: ~65,000 gas
• Uniswap V3 swap: ~150,000 gas
• Deploy a basic smart contract: 500,000 - 2,000,000 gas
• Mint an NFT: 80,000 - 200,000 gas

Gas price (denominated in Gwei) varies with network congestion. Each block has a target gas usage; if the previous block used more than the target, gas price rises; less, it falls (the EIP-1559 mechanism, August 2021).

Total fee paid: fee = gas_used × gas_price. A simple transfer at 30 Gwei: 21,000 × 30 = 630,000 Gwei = 0.00063 ETH. At $3,000/ETH that’s about $1.89.

Post-EIP-1559 the gas price has two parts: base fee (set algorithmically, burned permanently) and priority fee (tip to validators, kept by them). The base fee burn is one source of Ethereum’s deflationary pressure — in high-usage periods, more ETH is burned via base fees than is issued in block rewards.