What Are Gas Fees? Why Blockchain Network Fees Change and How to Save

Gas fees accompany cryptocurrency transfers and token swaps. If you have wondered why the same transfer can cost a few hundred Korean won one day and tens of thousands another, start with how these fees work.

What is a gas fee?

A gas fee is the network fee paid to have a transaction processed on a blockchain. Blockchain transactions are recorded and checked by miners or validators distributed around the world, and they do not work for free. Gas is the cost of getting a transaction included in a block.

The name “gas” is an analogy with vehicle fuel. Just as a car needs fuel to move, a blockchain needs gas to execute transfers, token swaps, NFT purchases and other operations. More complex work, such as a DeFi transaction rather than a simple transfer, consumes more gas.

Why do gas fees change?

The main reason gas fees fluctuate is supply and demand. A block has limited transaction capacity. When many people transact at once, they compete by offering higher fees for earlier processing. This resembles an auction: congestion pushes fees up.

• Network congestion: Popular NFT mints, major airdrops and sharp price moves can cause transaction surges and higher fees.
• Transaction complexity: Staking, swaps and multi-step smart contracts consume more gas than simple transfers.
• Network type: The same operation can cost tens or hundreds of times more on one chain than another.

During volatile markets with surging trading volume, exchange deposits and withdrawals can coincide with heavy on-chain activity, commonly pushing gas fees to several times their usual level.

Ethereum's gas structure

Ethereum is the network most closely associated with gas fees. Its fees are generally calculated as follows.

Gas fee = gas used × gas price (Gwei)

Gwei is a unit of gas price: 1 Gwei equals 0.000000001 ETH, or one billionth of an ETH. Since the 2021 London upgrade, EIP-1559, fees have been divided into a network-set base fee and a priority fee, or tip, paid to validators.

Practical ways to reduce gas fees

You cannot control the market price of gas, but your choices can substantially reduce the cost.

1. Choose the network: Instead of Ethereum mainnet, layer 2 networks such as Arbitrum and Optimism, or lower-cost chains such as Polygon and Solana, may handle the same operation at a fraction of the cost—tens or hundreds of times less. Always confirm that the asset you are sending supports that chain.
2. Choose the time: Congestion often rises during the overlap of US and European trading hours, corresponding to night through early morning in Korea. Quieter periods, such as weekend mornings, often offer lower gas prices.
3. Use gas-tracking tools: Check current Gwei prices with tools such as Etherscan's Gas Tracker. If the transaction is not urgent, wait for a lower reading.
4. Combine transfers: Sending once rather than splitting a transfer into several transactions can reduce repeated basic costs.

However, setting gas too low can leave a transaction waiting for a long time or cause it to fail, and gas fees may not be refunded after failure. The cheapest chain is not necessarily the safest. Consider asset compatibility and network reliability together, and choose carefully according to your wallet and capital-management principles.