What Are Gas Fees and Why Do They Change?

What you are paying for

Every blockchain has limited capacity per block. Gas is the unit measuring how much of that capacity your transaction consumes, and the fee is what you pay to have it included.

A simple transfer consumes little. A complex smart contract interaction consumes considerably more, because it makes the network do more work.

Why the price moves

Blockspace is auctioned. When more transactions compete than fit in a block, the ones paying more get included first. Demand changes minute to minute, so the price does too.

The fee has two parts on most networks: a base fee that adjusts algorithmically with congestion, and a priority fee you add to jump the queue. Your total is roughly gas used, multiplied by base fee plus priority fee.

What makes fees spike

A heavily anticipated token launch or mint
Sharp market moves, when everyone transacts at once
Large liquidations cascading through lending protocols
Airdrop claims opening

These are all correlated with the moments you most want to transact, which is the frustrating part.

How to pay less

Check current rates on a gas tracker before transacting rather than accepting the default.
Wait if you can. Fees vary by an order of magnitude across a day; nothing routine needs to happen in the next ten minutes.
Use a Layer 2. Layer 2 networks settle to the main chain in batches, which is why their fees are a fraction of it.
Batch your actions where the application supports it.
Set approvals thoughtfully. Repeatedly re-approving tokens costs gas each time.

Fees differ hugely by network

Network type	Typical cost profile
Ethereum mainnet	Highest; varies widely with congestion
Layer 2 rollups	A small fraction of mainnet
Alternative Layer 1s	Usually low, with different trade-offs
Bitcoin	Fee per byte of transaction size, not per computation

Low fees are not free performance. They generally reflect different choices about decentralisation, validator count or security model. Cheap is a trade-off, not a free improvement.

Failed transactions still cost

This catches people out: a transaction that runs out of gas or reverts still consumed computation, so the fee is still charged. You pay for the attempt, not the outcome.

Setting a gas limit too low to save money is therefore a false economy — it risks paying the fee and getting nothing.

Tax note for Indian users

Gas fees are generally not deductible from VDA gains under Section 115BBH, which permits only the cost of acquisition. See crypto tax calculation in India — this is one of the more expensive surprises for active on-chain users.

Gas limit versus gas price

Two separate numbers are often confused. The gas limit is the maximum units of computation you authorise; the gas price is what you pay per unit.

You are charged for gas actually used, not the limit — so setting a generous limit does not cost more, while setting one too low risks the transaction running out partway and failing while still charging for the work done. Wallets estimate the limit, and the estimate is usually right; overriding it downward to save money is rarely wise.

Approvals and why they cost twice

Using a token in a decentralised application typically takes two transactions: one approving the contract to move the token, then the action itself. Both cost gas.

This surprises people the first time. It also means that revoking approvals — a good security practice — costs gas as well, which is one reason so few people do it.

Priority fees and when to raise them

The priority fee is what actually determines your position in the queue when blocks are full. In calm conditions the minimum works fine. During congestion, a transaction with a low priority fee can sit pending for a long time.

Stuck transaction — most wallets allow a speed-up, which resubmits with a higher fee.
Cancelling — send a zero-value transaction to yourself with the same nonce and a higher fee, which replaces the pending one.
Nonce order matters — a stuck low-nonce transaction blocks every later one from that address until it clears.

Estimating before you commit

Before any expensive interaction, check the estimated fee in the wallet and compare it against what the action is worth. Claiming a small airdrop can cost more in gas than the tokens are worth, and the transaction is not reversible once sent.

For routine transfers, the combination of checking a gas tracker and using a Layer 2 where the destination supports it eliminates most of this cost entirely.