Definition
Gwei means gigawei, or one billion wei. Since one ETH contains one quintillion wei, one gwei equals 0.000000001 ETH. Gwei is a smaller unit of ether, not an independent token. It allows fee prices to be displayed without repeatedly writing many decimal places.
Gas Price versus Gas Quantity
Gas measures computational work, while gwei is often used to quote the ETH price per unit of gas. A transaction using 21,000 gas at an effective price of 10 gwei per gas would incur an execution fee of 210,000 gwei, or 0.00021 ETH. This is an illustrative calculation, not a current fee quote or a guarantee of the gas required by every transfer.
Key Considerations
The fiat cost also depends on ETH’s exchange rate. A displayed maximum fee per gas is a ceiling, not necessarily the effective price paid. Different networks may use similar terminology with their own native assets, and Layer 2 transactions can include additional data-related costs. Always check the network and the units before interpreting a fee estimate.