What Is a Wei?
A wei is the smallest unit of Ether (ETH), the native cryptocurrency of the Ethereum network. One ether equals 10^18 wei, so a single wei is one quintillionth of an ether. The unit exists because Ethereum records balances and payments as whole numbers, and tiny fractions of ether would otherwise require long decimal strings. The name honors Wei Dai, a cryptography researcher known for proposing early digital-currency ideas.
How It Is Used
Most people see amounts in ether, while the underlying software of wallets and the network itself works in wei. The relationship is fixed:
1 ETH = 10^18 wei
Other intermediate units also exist. A gwei equals one billion wei, and it is commonly used to express the cost of a transaction, known as a gas fee. Ether itself can be divided into these smaller units for convenience, but each step is a simple power of ten.
Why It Matters to Investors
Investors who hold ether or use Ethereum applications may encounter wei in wallet software, blockchain explorers, or transaction records. Recognizing the unit helps prevent misreading an amount by many orders of magnitude. For example, a value shown as 1,000,000,000,000,000,000 wei represents exactly 1 ETH.
Wei is a unit of measurement, not a separate asset. It does not carry its own market price, and its value depends entirely on the value of ether, which can rise or fall over time. Understanding the denomination makes records easier to read, but it does not indicate whether an asset is worth more or less.
Updated November 10, 2026. For general education only; not financial, tax or legal advice.