What are Wei, Gwei, and ETH?
Wei is the smallest, indivisible unit of Ether — everything on Ethereum is ultimately denominated in wei under the hood. One ETH equals exactly 1,000,000,000,000,000,000 (1018) wei. Gwei (“giga-wei”) sits in between: 1 Gwei equals 1,000,000,000 wei, and 1 ETH equals 1,000,000,000 Gwei. Gwei is the unit gas prices are quoted in, since wei values for gas would be unreadably long and ETH values would be inconveniently small.
Why this matters
Smart contracts, RPC responses, and block explorers routinely return values in wei — a raw integer with no decimal point, because the Ethereum Virtual Machine only understands integers; ETH’s 18 decimal places are a display convention layered on top. Converting by hand risks a stray zero, and floating-point math in a spreadsheet or browser console can silently round large wei values, since they exceed JavaScript’s safe integer range. This tool converts using arbitrary-precision integer (BigInt) arithmetic, so a value like 21,000 gas × 30 Gwei never loses precision, however many digits are involved.
How to use it
Type into any of the three fields — Wei, Gwei, or ETH — and the other two update instantly. Use the copy icon next to a field to grab the exact value for a transaction, a contract call, or a gas estimate, then paste it wherever you need it.