On Ethereum, a gas fee is units of gas used multiplied by the sum of the base fee and the priority fee. The ethereum.org gas guide gives this formula. Chainlink offers a broader definition. A gas fee is the cost a user pays to have a blockchain network carry out an operation. A plain transfer of ether (ETH) is listed at 21,000 units of gas. Gas fees are not fixed. They change with network congestion.
Key facts from the ethereum.org gas guide
- Formula: Units of gas used × (base fee + priority fee).
- Base fee: Set by the network. It has to be paid for a transaction.
- Priority fee: An optional tip that gives node operators a reason to include a transaction.
- Sending ETH: Listed at 21,000 units of gas.
- Price changes: Gas prices go up and down every twelve seconds, depending on congestion.
Why you pay a gas fee at all
Chainlink describes two jobs for gas fees. They compensate validators, who supply the computing resources that process transactions. They also help secure the network by preventing spam and malicious attacks. The ethereum.org guide makes the same point about spam. Because every computation costs gas, flooding Ethereum with expensive transactions costs the sender real money.
The formula, part by part
The ethereum.org guide splits the price of gas into two parts. The base fee is set by the network, and every transaction has to pay it. The priority fee is an optional tip for node operators to include a transaction. Both prices are added together and multiplied by the units of gas the transaction uses. One more term is easy to confuse with the fee. Chainlink defines the gas limit as the most computational units a user is willing to spend on an operation. It is a ceiling on work, not a price.
Work out a simple ETH transfer
Sending ETH is listed in the ethereum.org guide at 21,000 units of gas. The D'CENT wallet blog gives 21,000 as the gas limit for a simple Ethereum transfer. It also prices gas in gwei, a small unit of ETH, where one gwei equals 0.000000001 ETH. To get a fee, add the base fee and the priority fee in gwei. Multiply that sum by 21,000. Then convert the result from gwei to ETH.
Gas fee for a plain ETH transfer
Enter a base fee and a priority fee in gwei to see what a simple ETH transfer costs in ETH.
| Gas used to send ETH | Base fee | Priority fee (tip) | ETH per gwei | Fee for a plain ETH transfer |
|---|---|---|---|---|
| 21,000 gas | 20 gwei | 3 gwei | 0.000000001 ETH | 0.000483 ETH |
| 21,000 gas | 10 gwei | 2 gwei | 0.000000001 ETH | 0.000252 ETH |
| 21,000 gas | 30 gwei | 5 gwei | 0.000000001 ETH | 0.000735 ETH |
- The base fee and priority fee are figures you enter, not current network prices.
- The gas figure is the amount listed for sending ETH, not for other kinds of transactions.
No source gives a current base fee or priority fee, so the result is only as good as the gwei prices entered and covers a plain ETH transfer only.
Who receives each part
Chainlink says the base fee is often burned, which removes it from circulation. The priority fee acts as a tip that gives validators a reason to put a transaction ahead of others. Under the ethereum.org formula, the network sets the base fee and the tip is optional. That leaves the tip as the part of the price a sender chooses.
Why fees rise and fall
The ethereum.org guide says gas prices move up or down every twelve seconds. Fees begin to rise once the amount of computation on Ethereum passes a certain threshold. Chainlink describes what happens during a rush. More users try to transact than a block can hold, so the network becomes congested. Users then raise their priority fees to compete for block space.
How to pay less
The ethereum.org guide names timing and layer 2 among its ways to pay less. The first is timing. Ethereum is generally cheaper to use when North America is asleep. The second is to move the activity off the main network. Layer-2 chains are built on top of Ethereum. They offer lower fees and handle more transactions.
Analysis: what the formula leaves out
The formula has no term for the amount of ETH being sent. Read that way, a small transfer and a large one use the same listed 21,000 units of gas. The bill depends on the work a transaction needs and on two prices. Because those prices move every twelve seconds, a fee seen a minute ago is not a quote. Of the two prices, only the tip is set by the sender. That makes the tip, the time of sending and a layer-2 chain the sender's real choices.
Limits and next step
The formula and the 21,000 figure come from the undated ethereum.org guide. They describe Ethereum. The sources here do not set out fee formulas for other blockchains. The ethereum.org gas guide remains the place to check the formula and its terms. A separate explainer covers how to use a blockchain explorer to check a transfer. Before you confirm a transfer, check the fee your wallet shows against the gas fee formula. Then rerun the calculator with the base fee and priority fee you see.
Sources: What Are Gas Fees? A Guide to Blockchain Costs | Chainlink (chain.link), accessed Oct 14, 2026 · Ethereum fees: what is gas and how to pay less? | ethereum.org (ethereum.org), accessed Oct 14, 2026 · What is a Gas Fee? Understanding Blockchain Transaction Fees & How to (store.dcentwallet.com), accessed Oct 14, 2026
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