Gwei
A subunit of Ether equal to one billionth of an ETH (10⁻⁹ ETH). Gas prices on Ethereum are quoted in gwei because individual transactions cost only fractions of an ETH.
The unit hierarchy
Ether has multiple denominations, each useful at different scales:
- 1 ETH = 10¹⁸ wei (the base unit)
- 1 gwei = 10⁹ wei = 0.000000001 ETH
- 1 wei = the smallest unit possible
Gwei sits at a useful middle layer. Gas prices are typically 10-100 gwei, which is small enough to be meaningful per transaction but large enough not to involve confusing scientific notation.
Why gwei is the standard for gas
Average Ethereum gas fees are denominated in fractional ETH amounts that wouldn't be readable without a smaller unit. A typical transaction might cost 0.005 ETH at 25 gwei × 200,000 gas. Quoting "25 gwei" is much easier to communicate and compare than "0.000000025 ETH per gas unit."
Most wallet UIs default to gwei when showing gas prices. Block explorers (Etherscan) report gas in gwei. Gas-tracking services (ETH Gas Station, Blocknative Gas Estimator) all use gwei.
Common gas-price ranges
A rough sense of what different gwei levels mean:
- Below 10 gwei — quiet network, off-peak hours.
- 10-30 gwei — typical normal conditions.
- 30-80 gwei — busy network.
- 100+ gwei — congestion; major events (popular NFT mints, market volatility).
- 200+ gwei — extreme conditions, sometimes seen during peak NFT manias or market crashes.
Where gwei appears
A few practical contexts:
- Wallet "fast/average/slow" gas options — usually expressed in gwei.
- Setting custom gas prices — when manually adjusting, you specify gwei.
- EIP-1559 base fee and priority fee — both in gwei.
- Etherscan transaction details — show gas price in gwei.
Honoring Wei Dai
The unit is named after Wei Dai, a computer scientist who proposed "b-money" in 1998 — one of the earliest precursors to Bitcoin. Satoshi Nakamoto cited b-money in the Bitcoin whitepaper. Naming the smallest Ether unit after Wei Dai is a tribute to the lineage of cryptocurrency ideas.