Gwei, short for giga-wei, is a denomination of ether (ETH) equal to one billion wei, or one billionth of an ether. It is the unit in which Ethereum users, wallets and developers quote gas prices: the base fee, the priority fee and the maximum fee a sender is willing to pay for each unit of gas.
Gwei exists for readability. Gas prices expressed in ether would need eight or more zeros after the decimal point, and in wei they would run to ten or eleven digits. A billionth of an ether turned out to be a convenient size, so wallets, fee trackers and block explorers show prices such as "12 gwei" rather than "0.000000012 ETH". In older developer libraries the same unit is also called the shannon, after the information theorist Claude Shannon.
Gwei in plain terms
Petrol stations price fuel per litre, often to a tenth of a cent, even though nobody pays with tenths of a cent. The small unit makes it easy to compare prices; the final bill is rounded into ordinary money.
Gwei plays the same role for Ethereum's "fuel". The gas price tells you what one unit of computation costs, in a unit small enough to compare at a glance. Multiply it by the amount of work your transaction needs and you get the bill, which a wallet then shows in ether or in dollars.
Conversions
The relationships between the three units in daily use are fixed:
| Unit | In wei | In gwei | In ether |
|---|---|---|---|
| 1 wei | 1 | ||
| 1 gwei | 1 | ||
| 1 ether | 1 |
The full list of historical unit names, from kwei to finney, is in the wei entry. Converting a fee quoted in gwei into ether is a division by one billion:
- is the amount of computational work the transaction consumed.
- is the effective price per unit: base fee plus priority fee.
- is the number of gwei in one ether.
Example: a token transfer under the ERC-20 standard uses about 50,000 gas. At an effective price of 15 gwei, the fee is 50,000 × 15 = 750,000 gwei, and 750,000 ÷ 1,000,000,000 = 0.00075 ETH. If ether traded at $3,000, that would be $2.25; at 1.5 gwei it would be a tenth of that.
Reading a fee screen
Since the London upgrade of August 2021, wallets ask for several numbers in gwei. Each corresponds to a field of an Ethereum Improvement Proposal (EIP) 1559 transaction:
- Base fee. The protocol price per gas for the next block, burned when paid. The wallet reads it from the latest block and the user cannot change it.
- Priority fee (tip). An amount per gas offered to the validator for including the transaction; often 1 to 2 gwei in quiet periods.
- Max fee. The highest total price per gas the user will accept, a safeguard against a rising base fee.
The fee screen also shows the gas limit, which is a count of gas units, not gwei. Mixing up the two is a common beginner error: setting "21,000" in the price field instead of the limit field would offer 21,000 gwei per unit, and a wallet should warn before signing. The overall cost model is described in the gas fee entry.
Typical levels and what drives them
Gas prices measured in gwei swing widely. During the NFT and decentralized finance (DeFi) booms of 2020 and 2021, base fees of more than 100 gwei were common at busy moments. After validators raised the block gas limit several times in 2025, and with most retail activity moved to Layer 2 networks, mainnet base fees at times fell below 1 gwei. Wallets therefore often display gas prices with decimals, such as 0.4 gwei.
Gwei is used the same way on Ethereum-compatible blockchains, including BNB Chain, Polygon and Avalanche C-Chain, even though their native coins are not ether. There "gwei" means one billionth of the chain's own coin, so the same number of gwei does not mean the same fee in dollars on different networks.
Gwei in code and accounting
Smart contracts never store gwei directly; the Ethereum Virtual Machine (EVM) works only in wei. In Solidity the literal 1 gwei is shorthand that the compiler turns into 1,000,000,000 wei. Libraries in a typical Ethereum software development kit (SDK) offer helpers that parse and format gwei for the same reason.
For finance teams, the practical advice is to record fees in wei or ETH, which are exact, and treat gwei purely as a display unit. Reports of transaction fees paid by a treasury or a payment service are then reconciled against the on-chain record without rounding differences, and can be matched to burned supply figures where needed.