Glossary A–Z

Gas

Gas is the unit Ethereum uses to measure how much computation a transaction needs. The gas fee is that amount multiplied by a price per unit, paid in ETH.

By TokenTrail Editorial2 min read · 6 sources
Black-and-white photo of a petrol station at night in fog

Photo: “Untitled” by fusion-of-horizons, CC BY 2.0, via Flickr (edited: cropped and resized).

Quick answer

Gas is the unit that measures the computational effort an operation takes on Ethereum [1]. Your fee equals the gas used multiplied by the base fee plus a tip, quoted in gwei and paid in ETH. A plain ETH transfer uses 21,000 gas [1].

Key points

  • 1Gas is an amount of work; gwei per gas is its price. The fee is the two multiplied together.
  • 2The base-fee part of the fee is burned; the tip goes to the validator.
  • 3You pay for the gas used even if the transaction fails.

How does gas work?#

Every transaction on Ethereum is re-run by the network’s nodes, so every step of computation has a cost in gas. The Ethereum whitepaper introduced gas to stop accidental or hostile infinite loops: each transaction must set a limit on how many steps it may use [2]. That ceiling is the gas limit. A simple ETH transfer needs 21,000 gas, while a call to a smart contract needs more because the code does more work [1].

The price of gas is set in two parts. The base fee is calculated by the protocol from how full the previous block was and is burned. The priority fee, or tip, is chosen by you and paid to the validator who includes your transaction [1]. Prices are quoted in gwei: one gwei is one billionth of an ETH [3].

StepValue
Gas used21,000
Price per gas = 10 + 212 gwei
Fee = 21,000 × 12252,000 gwei = 0.000252 ETH
Of which burned = 21,000 × 100.00021 ETH
Of which paid to the validator = 21,000 × 20.000042 ETH

The fee is added on top of the amount sent; the recipient still gets the full amount.

Why is it called gas?#

ethereum.org compares it to the fuel a car needs to run [1]. A longer journey burns more fuel; a more complex transaction burns more gas. The fuel price changes from day to day, and so does the price per unit of gas. For the full mechanics, read Ethereum gas fees explained.

  • Gwei — one billionth of an ETH, the usual unit for gas prices.
  • Gas limit — the most gas a transaction (or a whole block) may use.
  • Base fee — the protocol-set price per gas that is burned; see EIP-1559 explained.
  • Smart contract — programs whose execution costs gas.
  • Mempool — where transactions wait before a validator picks them, often by tip size.

Frequently asked questions#

What does “gas price” mean?

The price you pay per unit of gas, usually in gwei. Since EIP-1559 it is made up of the base fee plus your tip [4].

Can I pay gas with a token other than ETH?

Not on Ethereum itself. Gas fees have to be paid in ETH, Ethereum’s native currency [1]. Even wrapped ether (WETH) cannot pay gas natively [5].

Do other blockchains use gas?

Many networks built on the same design use the word. Ethereum rollups, for example, use a gas fee scheme much like Ethereum’s [6], but each network sets its own prices.

Sources#

Grade A = primary source (regulator, protocol specification, client code, original author). Grade B = expert secondary source used for explanation only.

  1. Aethereum.org. Ethereum gas and fees: technical overview, 2026.
  2. Aethereum.org (Vitalik Buterin). Ethereum Whitepaper, 2014.
  3. Aethereum.org. Ethereum glossary, 2026.
  4. AEthereum Improvement Proposals. EIP-1559: Fee market change for ETH 1.0 chain, 2019.
  5. Aethereum.org. What is Wrapped Ether (WETH), 2026.
  6. Aethereum.org. Optimistic rollups, 2026.