Wei

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Pronunciation

[way]

Analogy

Wei is to what a penny is to a quadrillion dollars—an extremely small but indivisible unit. Just as all dollar transactions ultimately resolve to pennies, all transactions are calculated in wei at the level, regardless of how large the amount.

Definition

The smallest indivisible unit of (ETH) in the , named after cryptographer Wei Dai. One wei equals 10^-18 ETH (0.000000000000000001 ), serving as the unit for all calculations and transactions.

Key Points Intro

Wei provides the atomic unit of measurement for all value and computation on .

Key Points

Equals one quintillionth (10^-18) of one ether.

The fundamental unit used internally by the Ethereum Virtual Machine.

All gas prices and transaction values are ultimately denominated in wei.

Named after Wei Dai, influential cryptographer and creator of b-money.

Example

When setting a for an , you might specify 30 (30 billion wei), and your total might cost 0.005 ETH, which the network processes as 5,000,000,000,000,000 wei.

Technical Deep Dive

uses wei as its unit for all -level calculations to avoid floating-point precision issues, similar to how uses satoshis. At the implementation level, values, prices, and account balances are stored and manipulated exclusively as integers representing wei amounts. The extremely small denomination was chosen to provide granularity for both value transfer and computational pricing, allowing precise economic mechanisms even if 's value increases substantially. defines a series of named denominations between wei and : kilowei (10^3), megawei (10^6), gigawei/gwei (10^9), microether (10^12), milliether (10^15), and (10^18), though wei, , and are the most commonly used in practice.

Caveat

While wei provides extreme precision, most user interfaces display values in or for practical usability. The extreme granularity of wei means that many wei-level denominations have effectively no real-world value individually, though they remain crucial for -level precision.

Related Terms

Blockchain & Cryptocurrency Glossary

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