Ethereum and EVM Concepts

Wei

Wei is the smallest possible unit of Ether (ETH), the cryptocurrency used on the Ethereum blockchain. Just like how a cent is a smaller part of a dollar (1 dollar = 100 cents), Wei is a tiny part of 1 Ether. However, the difference is that 1 Ether is made up of a massive number of Wei — exactly 1,000,000,000,000,000,000 Wei (1 quintillion).

Why is Wei Important?

Ethereum deals with very small transactions, like paying tiny amounts of gas fees for smart contracts and transactions. If we used whole numbers like 1 Ether for these small payments, it would be impossible to handle fractions properly. So, instead of using Ether directly, the network uses Wei to break Ether into very tiny parts. This ensures that every single transaction, even the smallest one, can be handled accurately without rounding errors.

Example

Let’s say you need to pay 0.000000000000000001 Ether in gas fees. Writing out so many decimal places is hard to manage, so Ethereum represents this as 1 Wei, which makes things much easier.

Key Points