What Is Gas? Ethereum Fees, Gwei and EIP-1559

Gas is the unit that measures computation on Ethereum. Every operation — a transfer, a swap, an NFT mint — consumes a fixed amount of gas, and you pay for it in ETH. A simple ETH transfer costs 21,000 gas; a DeFi swap can cost 150,000 or more.

The EIP-1559 formula

Fee = gasUsed × (base fee + priority fee). The base fee is set by the protocol per block and burned (destroyed), rising when blocks are full and falling when they are empty. The priority fee (tip) goes to the validator as an incentive to include your transaction quickly.

What is gwei?

Fees are quoted in gwei: 1 gwei = 0.000000001 ETH. Example: a transfer using 21,000 gas at 20 gwei base fee costs 21,000 × 20 gwei = 420,000 gwei = 0.00042 ETH. At $3,000/ETH that is about $1.26.

Why do fees spike?

• Block space is scarce by design — demand outbids supply.
• NFT mints, memecoin frenzies and airdrop claims crowd blocks.
• Liquidation cascades: everyone rushing to transact at once.

Paying less

• Transact off-peak (weekends and UTC night hours are usually cheaper).
• Use Layer-2 networks (Arbitrum, Base, Optimism) where fees are cents.
• Set a max fee you are willing to pay instead of accepting the wallet default.
• Check our gas tracker first — it shows live low/standard/fast tiers from real fee history.