What Are Gas Fees? Crypto Transaction Costs Explained (UK, 2026)

Gas fees are the cost of getting a transaction processed on a blockchain like Ethereum — you pay a small amount to the network to have your transfer, swap, or purchase confirmed. Think of it as postage for moving crypto: the network's computers do the work, and gas is how they're paid. Fees rise when lots of people are transacting at once and fall when it's quiet, so the same action can cost pennies one hour and pounds the next. On Ethereum you pay gas in ETH, even when moving other tokens.

The concept confuses newcomers because there's no fixed price list — the cost floats with demand, like surge pricing on a taxi app. Once you get that, gas stops being mysterious.

Why do I have to pay gas fees?

Because someone has to do the work of verifying and recording your transaction, and gas is how the network pays them. On a blockchain there's no central company running servers for free — instead, a global network of validators processes transactions, and gas fees reward them for that computing effort while also stopping people spamming the network with junk transactions.

So gas serves two purposes: it compensates the people keeping the network running, and it acts as a price signal that keeps the system from being flooded. Bitcoin has transaction fees too, though they work slightly differently; the "gas" terminology comes mainly from Ethereum. Our what is Ethereum guide covers how the network processes transactions in the first place.

Why are gas fees sometimes so high?

Because gas prices are set by demand — when the network is congested, users bid higher to get their transactions processed faster. If lots of people are trading, minting NFTs, or using DeFi at the same time, block space becomes scarce and the price to secure it rises. During big market moments, an Ethereum transaction that normally costs a little can spike sharply. It's an auction, essentially, and when demand surges, so does the clearing price.

This is why the same £10 swap can feel free one day and painfully expensive another. It also disproportionately hurts small transactions — paying several pounds in gas to move £20 of crypto makes no sense. Ethereum's upgrades and "layer-2" networks (built on top of Ethereum to process transactions more cheaply) are largely aimed at bringing these costs down, which we track in pieces like our Fusaka upgrade guide.

How can I reduce gas fees?

Transact when the network is quieter, use cheaper networks or layer-2s, and avoid unnecessary transactions. Practical ways UK users cut gas costs:

• Time it — fees tend to be lower during off-peak hours; there are trackers showing current gas prices.
• Use layer-2 networks — options built on top of Ethereum process transactions far more cheaply, though they add a step and their own risks.
• Consider lower-fee blockchains — networks like Solana have much lower transaction costs, which is part of their appeal, as our Ethereum vs Solana guide explains.
• Batch and plan — avoid lots of tiny separate transactions; each one costs gas.
• Don't over-transact — if you're just buying and holding on an exchange, you may not deal with gas directly at all.

For a simple buy-and-hold beginner, gas is often a non-issue — it mainly bites when you're actively using DeFi or moving tokens between wallets. Remember, too, that gas fees can sometimes count as an allowable cost for UK tax purposes, as our allowable expenses guide notes.

Frequently asked questions

What exactly are gas fees? Gas fees are payments to a blockchain network for processing your transaction — verifying it and recording it on the chain. On Ethereum you pay them in ETH. They compensate the validators doing the work and prevent network spam. The amount varies with how busy the network is.

Why do gas fees keep changing? Because they're set by supply and demand for block space. When many people transact at once, they bid higher to be processed quickly, pushing fees up. When the network is quiet, fees fall. There's no fixed price — it floats like surge pricing.

Do I pay gas fees buying crypto on an exchange? Often not directly — the exchange handles on-chain costs, though they may be built into its own fees. Gas becomes visible mainly when you move crypto to your own wallet or use DeFi apps. Simple buy-and-hold users may rarely deal with gas.

How do I pay lower gas fees? Transact during quieter periods, use layer-2 networks or lower-fee blockchains like Solana, avoid many tiny transactions, and don't transact when you don't need to. For active DeFi users these choices matter; for buy-and-hold investors, gas is usually a minor concern.

Are gas fees tax deductible in the UK? Sometimes. Transaction costs, including certain gas fees directly tied to buying or selling, can count as allowable costs that reduce a capital gain. The rules are specific, so keep records. Our allowable expenses guide covers what qualifies.

The practical next step

If you're just buying and holding on an exchange, gas fees probably won't affect you much — but once you start moving crypto to your own wallet or using DeFi, check current gas prices before you transact and consider cheaper networks or off-peak timing. Never let a rushed transaction cost you more in gas than it's worth. This isn't financial advice. To understand the network behind these fees, read our what is Ethereum guide.