Wei (Ether Denomination)
Wei is the smallest denomination of ether — 1 ETH equals 10^18 wei. Gas prices are quoted in gwei (10^9 wei), and Ethereum tooling works in wei to avoid floating-point error.
The denomination table
The units you will actually meet: wei (1), gwei (10^9 — gas prices and tips), and ether (10^18). Between them sit legacy names from Ethereum’s early days — kwei, finney (10^15), szabo — which surface in old documentation but rarely in practice.
Everything on-chain counts in wei: balances, transfer amounts, gas price × gas used. Solidity arithmetic is integer-only, so contracts and calldata always express value in wei — which is why a transfer of 0.5 ETH appears as 500000000000000000 in the ABI-encoded arguments.
Gas economics
Transaction cost = gas used × gas price, where gas price is quoted in gwei. Since EIP-1559 the price splits into a burned base fee and a priority tip — both still denominated in gwei. Our converter translates between wei, gwei, finney, and ether instantly, and the units explainer walks through worked examples.
Related Standards
- •Ethereum yellow paper — denominations
- •EIP-1559 — fee market reform
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Further Reading
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