Recently, I’ve found that many people are completely confused about Ethereum Gas, so I thought, why not just put together a practical guide.

Let’s start with the most core thing first: what is Gas? Simply put, Gas is the “fuel” you need to pay to carry out operations on the Ethereum network. Whether you’re transferring funds, swapping tokens, or interacting with a smart contract, you have to pay Gas fees. This concept is actually easy to understand—just like you need to add gasoline to drive a car.

When I first got into it, I was also confused by all kinds of explanations. Some people said Gas is consumption, and others said it’s a fee. Only later did I realize that you just need to remember one formula: fee = quantity × price.

For example, if you drive from point A to point B and consume 10 liters of gasoline, with each liter costing 8, then your fee is 80. Ethereum is the same. Suppose sending tokens requires 21000 units of Gas, and the Gas price is 100 gwei per unit—then the fee is 21000 × 100 = 2100000 gwei. See? Gas is basically that simple.

So what is Gas Limit? It’s the maximum amount of Gas you’re willing to pay for a transaction. Wallets usually set it automatically. If the actual amount consumed is less than this limit, the extra money will be refunded. But don’t think about lowering the Gas Limit to save money—your transaction is very likely to fail, and the fee will still be deducted. It’s not worth it.

Next, Gas price—this is the unit price of Gas. Why is it expressed in Gwei instead of ETH? Because 1 Gwei equals 0.0000000001 ETH, so saying “Gwei” just sounds more natural. After the London upgrade, Gas price became a bit more complicated: it is split into two parts—base fee and a tip (Max priority fee). The base fee is the network’s base price, and the tip is the incentive you give to miners. If you want your transaction to be confirmed quickly, you need to add a bit more to the tip.

The actual amount you pay is called the Gas fee—this is the final fee expressed in ETH or Gwei. The calculation method is still that same formula: Gas fee = Gas Limit × Gas price. For example, if Gas Limit is 21000 and Gas price is 63.97 gwei, then the Gas fee equals 1343454 gwei. Converted to ETH, that’s 0.001343 ETH.

Why are Gas fees sometimes so unbearably expensive? Mainly because Ethereum block space is limited. When there are hot events or periods of high demand, everyone rushes to get their transactions on-chain, which drives Gas prices up. From my experience, if you’re not in a hurry, try to do transactions in the afternoon to evening, when Gas prices are relatively stable.

If you want to save on Gas fees, here are a few strategies: First, check the current Gas price before you act—don’t submit blindly. Second, if there’s no urgent need, choose off-peak times. Third, consider using Layer 2 networks or sidechains, such as Polygon—Gas fees are much lower, especially suitable for airdrop interactions.

My strategy right now is: for small transactions, use sidechains like Polygon; for large transactions, use the Ethereum mainnet. This way, I can save a lot of money. Once you’ve grasped what Gas is, how to calculate it, and how to save on fees, you can avoid a lot of detours on Ethereum. If you’re interested, you can go check Gate for real-time data on different assets, try calculating it yourself, and deepen your understanding.