Gwei is a small unit of ETH equal to one billion wei, or 0.000000001 ETH. Gas prices are quoted in gwei because the numbers are easier to read than tiny fractions of an ETH.

Do I pay gas if my transaction fails?

Usually yes. A transaction that runs out of gas or is reverted still pays for the computation performed, because validators did the work. Only transactions rejected before execution cost nothing.

What is the cheapest way to use Ethereum?

Using a layer 2 network such as Arbitrum, Optimism or Base is typically the cheapest, with simple transactions often costing a cent or less. On mainnet, sending transactions during quiet periods with a modest tip helps.

Who receives Ethereum gas fees?

The base fee is burned, so nobody receives it and that ETH leaves circulation. The priority fee (tip) goes to the validator that includes your transaction in a block.

Why do I need ETH to send stablecoins?

All transactions on Ethereum and most of its layer 2 networks pay gas in ETH, regardless of which token you move. Without a small ETH balance on the right network, you cannot send your tokens.

Ethereum Gas Fees: How They Work and How to Pay Less

Q: How are Ethereum gas fees calculated?

Multiply the gas your transaction uses by the base fee plus your priority fee, both in gwei, then divide by 1,000,000,000 to get ETH. For example, 21,000 gas × 21 gwei = 441,000 gwei, or 0.000441 ETH.

Q: Why are Ethereum gas fees so high sometimes?

Block space is limited, and the base fee rises up to 12.5% for every block that is more than half full. During market swings, popular launches or bot competition, many full blocks in a row can push fees up several times within minutes.

Ethereum gas fees are what you pay, in ETH, for the computing work your transaction asks the network to do. The fee equals the amount of work (measured in units of gas) multiplied by the price per unit (measured in gwei). A simple ETH transfer uses 21,000 gas; a token swap or NFT mint uses several times more, so it costs more.

The price per unit is not set by any company. It moves block by block with demand, following rules introduced by an upgrade called EIP-1559 in August 2021. Part of every fee is burned, permanently removing that ETH from supply, and the rest goes to the validator as a tip.

This guide explains how Ethereum gas fees are calculated, with a step-by-step example from gas units to dollars, why fees spike, why failed transactions still cost money, and the practical ways to pay less.

What Are Ethereum Gas Fees?

Every action on Ethereum, from sending ETH to trading on a decentralized exchange, runs as code on thousands of computers. Gas is the unit that measures how much computation and storage an action uses. Fees exist for two reasons: they pay validators (the computers that propose and confirm blocks) for including your transaction, and they stop anyone from spamming the network with endless or wasteful code, because every step costs money.

It helps to separate three ideas that people often blur together:

Gas used (gas units): how much work the transaction needs. This depends on what you do, not on how busy the network is.
Gas price: how much you pay per unit of gas, quoted in gwei. This depends on network demand.
Gas limit: the maximum number of gas units you allow the transaction to use. Your wallet estimates it automatically as a safety cap.

The fee you actually pay is: gas used × (base fee + priority fee). The rest of this guide unpacks each part.

Gwei Explained: The Unit Behind Gas Prices

ETH can be split into very small units. The smallest is the wei: one ETH equals one quintillion (10 to the power of 18) wei. Writing gas prices in ETH or wei would mean awkward numbers, so the ecosystem uses gwei (“giga-wei”), which is one billion wei.

Unit	Value in wei	Value in ETH
1 wei	1	0.000000000000000001
1 gwei	1,000,000,000	0.000000001
1 ETH	1,000,000,000,000,000,000	1

So a gas price of 10 gwei means 10 billionths of an ETH per unit of gas. To turn any fee into ETH, multiply gas units by gwei and divide by 1,000,000,000.

Gas Units vs Gas Price: What Different Transactions Use

The number of gas units is fixed by the operations a transaction performs. Ethereum’s rules assign a cost to each step: reading data, writing to storage, running a calculation. Writing new data to the blockchain is among the most expensive steps, which is why complex smart contract interactions cost more.

Action	Approximate gas used
Send ETH to another address	21,000 (fixed)
Send an ERC-20 token (for example, a stablecoin)	About 45,000–65,000
Approve a token for a dapp	About 45,000
Swap tokens on a decentralized exchange	About 100,000–200,000 or more
Mint an NFT	Varies widely, often 50,000–200,000+

The figures other than the ETH transfer are rough ranges; the exact amount depends on the specific contract and your wallet’s state. Your wallet shows an estimate before you confirm.

How Are Ethereum Gas Fees Calculated? Base Fee and Priority Fee (EIP-1559)

Before August 2021, Ethereum used a simple auction: you named a gas price, and validators (then miners) picked the highest bids. Fees were hard to predict and users often overpaid. The London upgrade introduced EIP-1559, which splits the price per gas unit into two parts.

The base fee

The base fee is a minimum price per gas unit that every transaction in a block must pay. The protocol sets it automatically based on how full the previous block was. Each block has a target size equal to half its gas limit (the maximum gas a block can hold):

If the previous block used more gas than the target, the base fee rises, by up to 12.5%.
If it used less, the base fee falls, by up to 12.5%.

The base fee is burned, meaning that ETH is destroyed rather than paid to anyone. This removes ETH from circulation and prevents validators from stuffing blocks with their own transactions to push fees up. During busy periods, the burn can exceed the new ETH issued to stakers, making total supply shrink; during quiet periods, supply grows slightly. You can follow the running total on sites such as ultrasound.money.

The priority fee (tip)

The priority fee, or tip, is an extra amount per gas unit that goes to the validator who includes your transaction. When the network is calm, a small tip is enough. When many people are competing for space, a higher tip can get you into the next block faster.

The max fee and refunds

Your wallet also sets a max fee per gas, the most you are willing to pay per unit. Because the base fee can change between the moment you sign and the moment your transaction lands, the max fee gives you a buffer. You never pay more than base fee plus tip; any difference up to your max fee is never charged.

Worked Example: From Gas Units to Dollars

Example: Suppose you send ETH to a friend. All prices below are hypothetical.

Gas used: 21,000 (a standard ETH transfer)
Base fee: 20 gwei; priority fee: 1 gwei; total: 21 gwei per gas
Fee in gwei: 21,000 × 21 = 441,000 gwei
Fee in ETH: 441,000 / 1,000,000,000 = 0.000441 ETH
Fee in dollars at an ETH price of $3,000: 0.000441 × $3,000 = $1.32

Of that fee, 21,000 × 20 = 420,000 gwei (0.00042 ETH) is burned, and 21,000 × 1 = 21,000 gwei (0.000021 ETH) goes to the validator.

Now suppose you set a max fee of 40 gwei. You still pay only 21 gwei per gas; the 19 gwei per gas of headroom (399,000 gwei in total) is simply never charged.

Finally, the same prices applied to a token swap using 150,000 gas: 150,000 × 21 = 3,150,000 gwei = 0.00315 ETH, or about $9.45. Same network, same moment, roughly seven times the cost, because the swap does more work.

The formula is always the same: fee in ETH = gas used × (base fee + tip) in gwei ÷ 1,000,000,000. Multiply by the current ETH price for a dollar figure.

Why Are Ethereum Gas Fees So High Sometimes?

Block space is limited. When demand for it outruns supply, the base fee climbs block after block. Because each full block can raise the base fee by 12.5%, increases compound fast: ten full blocks in a row multiply it by 1.125 to the power of 10, about 3.2 times, in roughly two minutes (blocks arrive every 12 seconds).

Common triggers include:

Market volatility: sharp price moves send traders rushing to swap, rebalance or avoid liquidation on lending platforms.
Popular launches: token sales, NFT mints and airdrops where thousands of people transact at once.
Bots competing: automated traders pay high tips to get ahead of others in the same block.
Complex transactions: even at normal gas prices, a multi-step DeFi transaction uses far more gas than a transfer.

During the 2021 DeFi and NFT boom, mainnet fees regularly reached tens of dollars for simple actions. Since then, two changes have eased pressure: much activity moved to layer 2 networks, and validators have voted to raise the block gas limit several times since early 2025, adding capacity. Fees still spike during busy periods, so check a live tracker such as Etherscan’s Gas Tracker before you transact.

Failed transactions still cost gas. If a transaction runs out of gas or is reverted, for example because a swap’s price moved beyond your slippage limit, its changes are undone, but you still pay for the computation already performed. If it runs out of gas, you lose the full gas limit you set. Only transactions rejected before execution, such as one with a gas limit below the minimum, cost nothing.

How to Pay Lower Ethereum Gas Fees

1. Use a layer 2 network

This is the biggest saving. Layer 2 (L2) networks such as Arbitrum, Optimism and Base process transactions off Ethereum’s main chain and post compressed batches back to it. Since the Dencun upgrade in March 2024 added cheaper “blob” data space for rollups (EIP-4844), simple L2 transactions often cost a cent or less, though fees vary. Many popular apps run on L2s, and many exchanges let you withdraw directly to them. Our Ethereum layer 2 guide explains how rollups work and their trade-offs.

2. Time your transactions

Demand follows human activity. Fees tend to be lower on weekends and during hours when both US and European markets are quiet, though patterns are not guaranteed. If a transaction is not urgent, check a gas tracker and wait for a dip.

3. Do not overpay the tip

Wallets usually offer “low”, “market” and “aggressive” settings. Unless you are racing for something time-sensitive, the default or low setting usually confirms within a few blocks. Remember that the base fee is the same for everyone in a block; only the tip is your choice.

4. Batch and simplify

Each separate transaction pays its own overhead. Combining actions where an app allows it, avoiding unnecessary approvals and consolidating small moves into fewer, larger ones all reduce total gas. Use exact token approvals so you do not need to repeat risky unlimited ones, then revoke approvals you no longer need.

5. Check the fee before you sign

If your wallet shows a fee that seems far too high, stop. It can mean the transaction is likely to fail, the network is congested, or the contract is doing more than you expect.

Gas Fees on Mainnet vs Layer 2: Quick Comparison

Feature	Ethereum mainnet (layer 1)	Layer 2 rollups
Fee structure	Base fee (burned) plus priority fee	L2 execution fee plus a share of the cost to post data to Ethereum
Typical simple transaction	Cents to dollars, more when busy	Often a cent or less
Security	Ethereum’s validator set directly	Relies on Ethereum plus the rollup’s own design and operators
Best for	Large transfers, assets only on mainnet	Everyday swaps, payments, small amounts
Fee paid in	ETH	Usually ETH

Whichever network you use, you need a small ETH balance on that network for gas, even if you are only moving stablecoins. Keep a little extra in your crypto wallet so you are never stuck with tokens you cannot move. To see what all this gas is paying for, read what Ethereum is used for, or compare Ethereum’s fee model with Bitcoin’s in Bitcoin vs Ethereum.

Bottom Line

An Ethereum gas fee is gas used multiplied by the base fee plus your tip, converted from gwei into ETH. The base fee is set by demand and burned; the tip goes to validators. Complex actions use more gas, busy periods raise the price, and failed transactions still cost money. For most everyday activity, a layer 2 network and a little patience cut your costs by far the most. For the wider context, see our Ethereum guide.

Ethereum Gas Fees: How They Work and How to Pay Less

What Are Ethereum Gas Fees?

Gwei Explained: The Unit Behind Gas Prices

Gas Units vs Gas Price: What Different Transactions Use