Crypto glossary
Gwei
Gwei is the unit used to price gas on Ethereum; one gwei equals one billionth of an ether (0.000000001 ETH), or one billion wei.
Ether can be divided to 18 decimal places, and the smallest unit is the wei, named after the computer scientist Wei Dai. Gwei, short for gigawei, equals one billion wei. Because gas prices expressed in ether would need long strings of zeros, wallets, block explorers and fee trackers quote them in gwei instead.
A transaction's cost is the gas it uses multiplied by the price per unit of gas, in gwei. Since EIP-1559, that price is the base fee set by the protocol plus the tip offered to the validator. In quiet periods Ethereum's base fee can fall below 1 gwei, while during popular NFT mints and market crashes it has spiked into the hundreds.
A low gwei figure does not guarantee a cheap transaction in dollars, since the final cost also depends on the gas used and the price of ETH. Setting the tip too low can leave a transaction stuck, which is why wallets usually estimate fees automatically.
Example
A simple ETH transfer uses 21,000 gas; at 10 gwei it costs 210,000 gwei, or 0.00021 ETH.
