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What is gwei?
Gwei is a small unit of ether used to quote gas prices. One gwei is one-billionth of an ETH (10^-9 ETH). Wallets show fees in gwei so the numbers are readable instead of long decimals.
What it means for you
A gas price in gwei is a price per unit of gas, not the total fee. The total is the gas used multiplied by the price, so check the fee your wallet shows in ETH or dollars before you sign, not just the gwei figure.
A common mistake: “A 30 gwei fee means I pay 30 gwei.”
In fact: 30 gwei is the price per unit of gas. A plain transfer uses 21,000 units, so at 30 gwei the fee is 630,000 gwei, or 0.00063 ETH; a contract call uses more units and costs more.
How it works
Ether's smallest unit is the wei: 1 ETH is 10^18 wei, so one gwei is 10^9 wei, or 10^-9 ETH. Gas prices are quoted per unit of gas in gwei: the base fee the protocol sets, plus the tip you offer the validator. The total fee is the units of gas used multiplied by that per-unit price, so the same gwei figure means a larger fee for a contract call that uses more gas than a plain 21,000-gas transfer.
An example
Say the base fee is 10 gwei and you tip 2 gwei. A plain transfer uses 21,000 gas, so the fee is 21,000 x 12 = 252,000 gwei, which is 0.000252 ETH. If ETH were $2,000, that would be about 50 cents.
Sources: ethereum.org: Gas and fees, ethereum.org: Transactions · checked 4 October 2026
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Educational content, not financial advice. Written by hand and checked against the source named above. Something wrong? Tell us and we reply within two business days.