Guide

What Is Ethereum Gas?

Gas is the unit EVM chains use to measure computation and storage costs. Transfers, approvals, swaps, and NFT minting all consume Gas.

Basic Formula

Fee = Gas Used × Gas Price

An ordinary ETH transfer typically consumes 21000 gas. Contract calls involve more logic and may consume tens to hundreds of thousands of gas.

Gas Limit Is Not Actual Gas Consumption

Gas Limit is the maximum gas a transaction is allowed to consume; the actual execution fee is calculated from the Gas Used in the receipt and the effective price. With 21,000 gas used at an effective price of 15 Gwei, the fee is 315,000 Gwei, or 0.000315 ETH. Failed transactions may also consume Gas.

What Is Gwei?

Gwei is a small denomination of ETH, commonly used to display gas price.1 Gwei = 10^-9 ETH。

Why Do Wallet Estimates Change?

Since EIP-1559, the base fee changes with block utilization, and the priority fee is paid to the block proposer. Effective price = min(maxFeePerGas, baseFee + maxPriorityFeePerGas); the fee cap must meet the requirements for inclusion in a block. For example, with a base fee of 12 Gwei, a priority fee cap of 2 Gwei, and a total fee cap of 20 Gwei, the effective price is 14 Gwei. The total cap is not necessarily the price charged.

References:Official Ethereum Gas Documentation. L2 data fees, blob transaction fees, and similar charges must be calculated separately.