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On Ethereum, gas is a unit of measurement that represents the computational effort required to complete a transaction on the network. It is the fuel you must buy to incentivize miners to add your transaction to a block. Read our ETH Gas 101 article for a comprehensive overview of ETH gas, gas pricing, and the challenges of estimating gas.

Yes, always. To transact on the Ethereum network, you are charged a fee, which is paid out to a miner who processes and validates the transaction. It is important to note that not all transactions will cost the same amount of gas. Depending on the size of the transaction and the number of transactions actively competing to be submitted on-chain, gas fees will vary.

EIP-1559 changed how Ethereum transaction fees are calculated and where those fees go. Instead of a singular Gas Price, you now have to pay attention to three separate values:

  • The Base Fee, which is determined by the network itself, is the first value to be aware of. It is subsequently burned during the transaction.
  • A Max Priority Fee, which is optional, determined by the user, and is paid directly to miners.
  • The Max Fee Per Gas is the absolute maximum you are willing to pay per unit of gas to get your transaction included in a block. For brevity and clarity, we will refer to this as the Max Fee.

Read more in our blog A Definitive Guide to Ethereum EIP-1559 Gas Fee Calculations: Base Fee, Priority Fee, Max Fee.

Gwei is the smallest denomination of ETH that is equivalent to 1/1,000,000,000 of 1 ETH (1 ETH = 1,000,000,000 gwei). All transaction fees on the Ethereum network are denominated in gwei.

Since one unit of gwei is an extremely small amount of Ethereum (0.000000001 ETH), it is much simpler to interpret and transact in terms of gwei rather than fractions of a fraction of ETH.

The base fee is an algorithmically determined fee that users on the Ethereum blockchain must pay to complete a transaction. The base fee is designed to help smooth transaction fees and prevent sudden price spikes by targeting 50% full blocks. Depending on how full the new block is, the Base Fee is automatically increased (the block is more than 50% full) or decreased (the block is less than 50% full). Visit our blog to learn more about EIP-1559 base fees.

The Priority Fee is an 'optional' additional fee set by the user and paid directly to miners to incentivize them to include your transaction in a block. It is sometimes referred to as the miner tip. Users will always be charged their Priority Fee. Visit our blog to learn more about priority fees.

The max fee is the absolute maximum amount you are willing to pay per unit of gas to get your transaction confirmed. It is an 'optional' additional fee that is paid directly to miners, and incentivizes miners to include your transaction in a block. By monitoring mempool data, Blocknative users can accurately set their max priority fee to increase the chances that their transaction is confirmed as fast as possible. Visit our blog to learn more about max fees.

You are rarely charged your max fee.

The gas limit is the maximum amount of gas miners are authorized to consume to complete a transaction. Visit our blog to read more on Ethereum transaction gas limits.

EIP-1559 added complexity to the Ethereum gas fee marketplace compared to the previous first-priced auction system. Users now have to factor in a multitude of variables including base fee, priority fee, and max fee. Visit the Blocknative blog to view our guide to EIP-1559’s impact on gas fee calculations.

Ethereum gas fees are lowest when there is the least amount of competition in the mempool. Users can monitor gas fees to receive ETH gas price alerts right in their browsers through Blocknative’s gas price extension for Chrome, Brave, or Firefox.

Ethereum fees are high when the network experiences a rapid spike in demand for getting transactions submitted on-chain. A common cause of an Ethereum transaction fees spike is a highly anticipated NFT release. During these drops, it’s common for users to set high priority fees to be competitive for inclusion in the subsequent blocks. Congestion builds in the mempool as more people try to mint the NFT, causing base fees to rise due to blocks being more than 50% full. You can see these public gas auctions in action in our presentation How Everything (and Nothing) Changes With Gas Fees.

Blocknative’s ETH Gas API Platform leverages real-time mempool data to help you maximize predictability, and avoid overpaying when gas fees are high.

No, gas is not refunded for failed transactions on Ethereum, since miners had to use resources to process the transaction before it ultimately failed. However, any excess gas will be refunded to the originator. Learn more about Ethereum transaction errors and how to avoid them.

You can track ETH gas fees live with Blocknative’s Gas Estimator, available through the web version, or as a browser extension for Chrome, Brave, and Firefox. Sign up for a free Blocknative account to get gas notifications directly through your extension.


Gas updates every second

A Definitive Guide to Ethereum EIP-1559 Gas Fee Calculations: Base Fee, Priority Fee, Max Fee
When Ethereum upgraded its core gas-fee marketplace with EIP-1559, transactions moved from a ...
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ETH Gas 101: An Introduction to Ethereum Gas for Traders and Builders
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Comparing Ethereum Gas Estimators: How Blocknative Gas Platform Stacks Up
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“Blocknative is a trusted provider of reliable and accurate gas estimation to help users stop overpaying in transaction fees. MetaMask is excited to integrate Blocknative along with our existing services. We look forward to continued collaboration on how to improve user experience and accessibility for the broader ecosystem.”

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