ChainTools

Ethereum Gas Calculator

Gas used times gas price — the formula behind every Ethereum transaction's cost.

Gas used (units)

Gas price (Gwei)

Cost (ETH)

0.001

A simple ETH transfer uses 21,000 gas; smart contract interactions (swaps, mints, etc.) use much more — check the specific transaction type.

What you entered

Gas used (units): 21000Gas price (Gwei): 30

1
Cost = gas used × gas price ÷ 1e9
21000 × 30 Gwei ÷ 1,000,000,000= 0.00063000 ETH

Result

Cost (ETH): 0.001

21000 gas at 30 Gwei costs 0.00063 ETH.

Ethereum gas cost by operation and gas price

Cost in ETH is gas units multiplied by gas price in gwei, divided by a billion. A plain ETH transfer is always 21,000 gas; contract calls use more.

Operation	Gas units	Gas price	Cost in ETH
ETH transfer	21,000	5 gwei	0.000105
ETH transfer	21,000	10 gwei	0.000210
ETH transfer	21,000	30 gwei	0.000630
ETH transfer	21,000	100 gwei	0.002100
ERC-20 transfer	65,000	30 gwei	0.001950
Token swap	150,000	30 gwei	0.004500

Gas units depend on what the transaction does and barely vary; gas price is set by network demand and can move twenty-fold in a day. That is the number to watch.

Different actions use very different amounts of gas

A simple ETH transfer costs a fixed 21,000 gas, but smart contract interactions like token swaps, NFT mints, or complex DeFi transactions can use hundreds of thousands of gas — check the specific transaction type's typical gas usage.

Gas price fluctuates with network demand

Gas price in Gwei rises and falls with how busy the Ethereum network is — the same transaction can cost dramatically more during periods of high demand than during quiet periods.

Frequently asked questions

A simple ETH transfer uses 21,000 gas at 30 Gwei — what does that cost?

0.00063 ETH. At a $3,000 ETH price, that's about $1.89. Simple transfers have a fixed 21,000 gas cost, so the total fee depends entirely on the current gas price.

Why did my token swap cost $50 in gas but a simple transfer cost $2?

Token swaps interact with smart contracts and consume much more gas — a Uniswap swap might use 150,000-300,000 gas versus 21,000 for a simple ETH transfer. The gas price is the same, but you're paying for 7-14x more computation.

How do I find the current gas price?

Check a gas tracker like Etherscan's gas tracker or GasNow. Gas prices vary by the minute — quiet periods (late nights, weekends) often have lower prices. Some wallets let you set custom gas prices to save money at the cost of slower confirmation.