Gwei (gigawei) is a unit of measurement for Ethereum gas prices. One gwei equals one billion wei, which equals 0.000000001 ETH. The term "gwei" comes from "gigawei," similar to how "gigabyte" represents one billion bytes. On the Ethereum network, gas prices are universally quoted in gwei because it provides a readable number scale. Instead of saying "30000000000 wei," it is much clearer to say "30 gwei."
Wei is the smallest unit of Ethereum, where 1 ETH equals 10^18 wei (one quintillion wei). Gwei (gigawei) equals 10^9 wei or 0.000000001 ETH. ETH (Ether) is the primary unit. On the blockchain, all values are stored as wei for precision, but users and applications quote gas prices in gwei for readability. This unit system allows for both large amounts and precise fractional values.
Gas is the unit of computational work on the Ethereum network. Every transaction or smart contract operation consumes a specific amount of gas, measured in units. The gas price (in gwei) is what you pay per unit of gas. The gas limit is the maximum amount of gas you are willing to spend. Total transaction cost = gas price (gwei) times gas limit (units). For example, a simple ETH transfer requires 21,000 gas. If gas price is 30 gwei, the total cost is 21,000 times 30 gwei or 0.00063 ETH.
A simple ETH transfer costs 21,000 gas. ERC-20 token transfers cost around 65,000 gas. Uniswap swaps typically consume 150,000 gas depending on the pair. NFT minting can cost 150,000 to 250,000 gas depending on the contract. Layer 2 solutions like Optimism and Arbitrum reduce gas costs by 10-50x through batching and compression.
Enter an amount in the input field and select a unit (wei, gwei, or ETH) to see conversions to all other units. The USD conversion uses live Ethereum price data. For gas cost estimation, enter a gas price in gwei and gas limit in units. Click any Common Gas Limits button to quickly set typical transaction types. The tool immediately calculates total ETH and USD cost. Click Copy Results to copy all values to your clipboard.
Ethereum gas prices fluctuate based on network demand. During periods of high activity, gas prices spike as users compete to get their transactions included in blocks. Standard gas price on mainnet ranges from 20 to 100 gwei during normal conditions, rising to 200+ gwei during congestion. Layer 2 networks like Arbitrum or Optimism have dramatically lower costs, often below 1 gwei equivalent. Always check current gas prices before sending transactions to avoid overpaying.
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