ETH gas fees are the cost of getting a transaction included on Ethereum. You pay gas units × gas price: a simple ETH transfer always uses 21,000 gas, swaps and other contract calls use more, and the gas price is the network’s base fee plus an optional priority fee (tip), both quoted in gwei (one billionth of an ETH). Since the Dencun upgrade in March 2024, layer 2 networks such as Arbitrum and Base post data to Ethereum far more cheaply, which is why moving activity to a layer 2 is the most reliable way to pay less.
Key Takeaways
- Formula: fee = gas used × (base fee + priority fee).
- ETH transfer: 21,000 gas; a swap often uses 100,000-200,000 gas or more.
- Base fee is burned: since EIP-1559 in 2021 it adjusts automatically with demand.
- Layer 2s: usually a small fraction of mainnet cost for the same action.
How the Fee Is Calculated
| Part | What it is |
|---|---|
| Gas used | Work the transaction needs: 21,000 for an ETH transfer, more for contracts |
| Base fee | Network price per gas unit, set by demand, burned |
| Priority fee | Tip to the block builder to include you sooner |
| Max fee | The most you agree to pay per gas; unused amount is refunded |
Example: an ETH transfer at a base fee of 2 gwei plus a 1 gwei tip costs 21,000 × 3 = 63,000 gwei, or 0.000063 ETH. The same transfer during a spike at 40 gwei costs 0.00084 ETH, more than 13 times as much.
Why Gas Fees Spike
Each block has a target size. When demand pushes blocks above target, the base fee rises block after block until demand cools. Popular token launches, NFT mints and sharp market moves, when traders rush to adjust positions, are the usual triggers. Live prices are on the Etherscan gas tracker.
Layer 2 Networks After Dencun
The Dencun upgrade (March 13, 2024) added “blobs”, a cheaper way for rollups to post data to Ethereum. Fees on Arbitrum, Optimism and Base dropped sharply as a result. For frequent swaps, keeping funds on a layer 2 usually saves more than any timing trick.
7 Ways to Pay Less Gas
- Use a layer 2 for regular activity.
- Transact at quiet times, often weekends and late US hours.
- Set a modest priority fee; wallets often default high.
- Avoid repeated approvals: approve once, carefully.
- Batch actions when an app supports it.
- Compare routes: an aggregator may find a route with fewer steps.
- Do not cancel and resend unless needed; each attempt costs gas.
Gas on Other Networks
Every network has its own fee token: SOL on Solana, BNB on BNB Chain, TRX on Tron. You always need a little of the native token to move anything: sending USDT on Tron, for example, still needs TRX.