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What are gas fees in crypto? How they work

What are gas fees in crypto? How they work
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Gas fees are what you pay to have a transaction processed on a blockchain. Miners or validators doing the work get compensated. Block space is finite, which is why a price exists at all.

Costs have collapsed on Ethereum's scaling networks. Following the Dencun upgrade in March 2024, Layer 2 fees fell from $0.50 to $5.00 down to roughly $0.001 to $0.05. That is a reduction of 80 to 90%.

Why gas fees exist at all

Two reasons, both structural.

Paying for work. Someone has to run the hardware that validates your transaction, records it, and keeps the resulting ledger available to everyone else. Fees fund that arrangement.

Rationing scarce space. Blocks hold a limited amount, and without a price attached to that space, spam would fill every one of them instantly and leave nothing for anyone with a genuine transaction to send. Fees make block space expensive enough that only transactions worth making get made.

People forget that second reason when complaining about cost. Free transactions produce unusable blocks.

How Ethereum prices gas

Three components since EIP-1559, which activated in August 2021.

ComponentWhat it doesWhere it goes
Base feeSet algorithmically by network demandBurned permanently
Priority feeOptional tip to get included fasterThe validator
Gas limitMaximum units you authorize for the transactionUnused portion refunded

Multiply gas used by the gas price and you have your total, denominated in gwei. One gwei is one billionth of an ETH.

Note what the base fee does. Burned permanently, it removes ETH from circulation, which is the mechanism behind Ethereum's token burn.

Why gas costs vary so much

  • Network demand. Base fee rises as blocks fill. A quiet Sunday costs a fraction of a busy launch day.
  • Transaction complexity. Sending ETH is cheap. A multi-step DeFi interaction touching several contracts costs considerably more.
  • The network you use. Same action, wildly different prices across chains.
  • Timing. Fee markets are cyclical, tracking activity in the dominant trading regions.
  • Token approvals. Granting a contract permission is a separate transaction with its own fee.

The Layer 2 fee shift after Dencun

This is the biggest structural change in crypto's fee landscape since Ethereum launched, and it deserves the detail.

Before March 2024, rollups posted transaction data to Ethereum as calldata, competing directly with everyone else for the same block space. Expensive. It also capped how cheap Layer 2 could get.

With EIP-4844 came blob-carrying transactions. Blobs form a separate data lane, priced independently and pruned after roughly 18 days. Rollups stopped competing with users for mainnet block space.

The effect landed immediately, and it has held since, reshaping where ordinary retail activity on Ethereum actually happens. By mid-2026, median fees sit around $0.02 to $0.05 on Base, roughly $0.07 on zkSync Era, and around $0.09 on Arbitrum One and OP Mainnet. On Base, simple transfers can drop to $0.0007.

Ethereum mainnet still costs more. Simple ETH transfers run $0.10 to $0.25, complex transactions $2 to $14. Against pre-Dencun conditions, where equivalent operations averaged far higher, L2 users see reductions exceeding 95%.

What gas fees are not

  • Not paid to a company. No exchange or foundation collects them. Validators and burn addresses do.
  • Not proportional to the amount sent. Moving $10 and $10 million cost the same, because the computation is identical.
  • Not refundable on failure. Reverting still consumed computation, so the fee still applies. This surprises people constantly.
  • Not a fixed price. Estimates are estimates. Between seeing a quote and landing your transaction, fees move.
  • Not payable in stablecoins, usually. Most networks require the native token, which is why holding USDC on Ethereum with no ETH means being unable to move it. Account abstraction is changing this.

Practical ways to reduce gas costs

Descriptively, since what suits you depends on what you are doing.

  • Use a Layer 2 where the application supports it. The difference is two orders of magnitude.
  • Transact during quiet periods, since base fees track demand.
  • Batch actions where the wallet allows it, combining approval and swap into one transaction.
  • Check the network before withdrawing from an exchange. Sending USDT over Tron costs less than over Ethereum, and the recipient must support that network.
  • Set a sensible gas limit rather than an inflated one, since the unused portion is refunded but a too-low limit wastes the fee on a failed transaction.

Where mb.io fits

Inside a centralized exchange, trades never touch a blockchain and incur no gas at all. Only deposits and withdrawals do.

mb.io is a regulated crypto spot exchange backed by MultiBank Group, a financial institution founded in 2005 that serves more than 2 million clients across 100+ countries.

  • Regulated by VARA in the UAE and AUSTRAC in Australia
  • Deposit and withdrawal flows that name the network explicitly before funds move
  • 10/10 security score from Hacken, an independent blockchain security auditor
  • Institutional-grade MPC custody powered by Fireblocks, with segregated client funds
  • Buy, sell, and swap in three steps, from sign-up to purchase
  • 24/7 multilingual customer support

Open your account and start trading on mb.io.

Frequently asked questions

Why are gas fees so expensive sometimes?

Because the base fee rises as blocks fill. Demand for block space sets the price, so heavy activity costs far more than quiet periods.

What is gwei?

A denomination of ETH used to price gas. One gwei is one billionth of an ETH, keeping fee figures readable without long decimal strings.

Do I get a gas refund if my transaction fails?

No. Failed transactions still consumed computation, so the fee still applies. Unused gas below your limit comes back. Work already done does not.

Why did Layer 2 fees drop so much?

EIP-4844, introduced in the Dencun upgrade of March 2024, gave rollups a separate data lane called blobs. Data-posting costs fell 80 to 90%, and fees dropped from dollars to fractions of a cent.

Can I pay gas fees in a stablecoin?

On most networks, no. Because fees require the native token, holding USDC on Ethereum without ETH leaves you unable to transact. Account abstraction is starting to change this.

Does the amount I send affect the gas fee?

No. Gas prices computation rather than value. Moving $10 and $10 million cost the same, since both require identical work.

Which network has the cheapest gas fees?

Among major Ethereum Layer 2 networks in mid-2026, Base sits lowest at roughly $0.02 per transaction. Arbitrum One and OP Mainnet run around $0.09. zkSync Era sits near $0.07.

Do centralized exchanges charge gas fees?

Not on trades, since those settle in the platform's internal ledger. Withdrawals move funds on-chain, so a network fee applies there.

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