// GLOSSARY -- BLOCKCHAIN & CRYPTO FUNDAMENTALS
What is Gwei?
Gwei (gigawei) is a denomination of Ether equal to 10^9 wei or 0.000000001 ETH — the standard unit for expressing Ethereum gas prices, making fee calculations human-readable.
WHY IT MATTERS
Gas prices on Ethereum are typically in the range of 1-500 gwei per unit of gas. Expressing this in ETH (0.000000001 - 0.0000005) or wei (1,000,000,000 - 500,000,000,000) would be unwieldy. Gwei is the Goldilocks unit.
When someone says 'gas is 30 gwei,' they mean each unit of gas costs 30 gwei. A simple ETH transfer uses 21,000 gas, so at 30 gwei it costs 21,000 × 30 = 630,000 gwei = 0.00063 ETH.
Understanding gwei is essential for managing transaction costs, setting gas prices, and building fee estimation into agent systems.
FREQUENTLY ASKED QUESTIONS
What's a normal gas price in gwei?
On Ethereum L1: 10-50 gwei during calm periods, 100-500+ during congestion. On L2s like Base and Arbitrum, the equivalent is fractions of a gwei.
How do I calculate transaction cost?
Gas used × gas price (in gwei) = cost in gwei. Convert to ETH by dividing by 10^9. A 21,000 gas transfer at 20 gwei = 420,000 gwei = 0.00042 ETH.
What is the base fee vs priority fee?
Since EIP-1559: base fee is burned (set by the protocol based on demand), priority fee (tip) goes to validators. You pay base fee + priority fee per gas unit.