Ethereum gas fee calculator
Gwei × gas × ETH price. Know the USD cost before you click confirm.
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Gas fees on Ethereum swing 10x in a single day. A Uniswap swap that costs $4 at 3 AM can cost $42 during a popular NFT mint. This calculator turns abstract 'gwei' numbers into the USD you'll actually pay.
The math is simple: gas price (gwei) × gas units × ETH price ÷ 1,000,000,000 = USD cost. The presets cover the four transactions that make up 95% of what you'll do on mainnet.
Most wallets show gas in gwei and leave it to you to do the conversion. At 20 gwei with ETH at $3,200, a simple ETH transfer costs $0.68. A Uniswap swap at the same price costs $8.20. An NFT mint from a hot collection during peak demand at 80 gwei and $3,500 ETH can run $63. These are not hypotheticals — all three happened repeatedly during the 2021 bull market and the 2023 memecoin season.
Understanding gas before you transact protects you from two common mistakes: confirming a trade that costs more in fees than the transaction is worth, and setting gas too low and watching your transaction stall in the mempool for hours while markets move. This calculator gives you the dollar number before you click confirm.
Uniswap swap at 35 gwei with ETH at $3,200
Gas units for a typical Uniswap V2/V3 swap: ~150,000.
Fee in ETH: (35 × 150,000) ÷ 1,000,000,000 = 0.00525 ETH.
Fee in USD: 0.00525 × $3,200 = $16.80.
Swap the same tokens on Arbitrum One: ~$0.40. On Base: ~$0.10.
Common gas-unit costs (what goes in the 'gas limit' box)
These are approximate units for standard operations. Your wallet (MetaMask, Rabby) will estimate the exact number before you confirm.
- ETH transfer: 21,000 gas (hardcoded minimum).
- ERC-20 transfer (USDC, USDT, etc.): 50,000-65,000 gas.
- Uniswap V3 swap: 130,000-180,000 gas.
- NFT mint: 150,000-300,000 gas.
- Contract deploy: 500,000-2,000,000+ gas depending on size.
When mainnet is worth it vs when to bridge to an L2
Rule of thumb: if your transaction value is under ~$1,000 and you're paying $20+ in gas, you're handing over 2%+ of the trade to validators. Bridge to Arbitrum, Base, or Optimism — bridging costs $2-5 one time, and subsequent transactions cost $0.05-$0.50. For one-off large trades ($20,000+), mainnet is often fine because the bridge round-trip adds friction that outweighs the fee savings on a single tx.
How Ethereum gas pricing actually works after EIP-1559
Before EIP-1559 (August 2021), you set a single gas price and miners picked the highest bidders. Now there are two components: the base fee (set by the protocol, burned permanently) and the priority fee, also called the tip (goes to the validator who includes your transaction). The base fee adjusts every block up or down by 12.5% depending on whether the previous block was more or less than 50% full.
This means gas prices trend predictably during off-peak hours and spike hard during congestion. Etherscan's gas tracker shows 7-day gas charts — a $4 swap window appears most weekday nights between midnight and 6 AM UTC. If you're not in a hurry, checking gas before transacting saves real money. On a 10-transaction month, picking the right gas windows can cut your total fee spend by 60-70%.
Your wallet's 'slow', 'medium', and 'fast' gas suggestions map to different priority fee levels. Slow usually sets a priority fee of 0.1 gwei above base fee — fine for non-urgent transfers. Fast sets 2-5 gwei tip — appropriate when you want inclusion in the next 1-2 blocks. Never set priority fee to 0 unless you're intentionally letting the tx sit indefinitely.
Layer 2 gas costs by network: real numbers
Arbitrum One processes transactions using its own sequencer, posting compressed data back to Ethereum mainnet. A typical swap costs $0.10-$0.50 depending on mainnet L1 data costs. Base, Coinbase's L2, runs on the OP Stack and averages $0.01-$0.10 per swap — among the cheapest in the Ethereum ecosystem. Optimism mainnet runs $0.05-$0.30. zkSync Era averages $0.05-$0.20 with batch compression.
The L2 gas cost isn't just the sequencer fee — it also includes a small L1 data fee that fluctuates with Ethereum mainnet congestion. When mainnet gas spikes to 150+ gwei, L2 data fees tick up too, though they're still 10-50x cheaper than mainnet. For everyday DeFi users doing 20-30 transactions a month, L2s save $200-$500 annually in fees versus staying on mainnet.
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Ethereum gas — frequently asked questions
Why do gas fees spike during NFT mints even if I'm not minting?
Every transaction competes for the same block space. A hot NFT mint drives thousands of wallets to bid up gas prices — that demand pressure shows up for every transaction happening at that moment. You pay whatever the current market rate is, regardless of what you're doing.
What's the difference between gas price and gas limit?
Gas price (gwei) is what you pay per unit of computation — bid price essentially. Gas limit is how many units your transaction consumes. Total fee = gas price × gas used. Setting a high gas limit doesn't cost more if the transaction uses less; unused gas is refunded.
Can I set gas too low and have my transaction stuck?
Yes. If you set a gas price below the current market, your tx sits in the mempool until either gas prices drop to your level, or you cancel. On MetaMask you can 'speed up' by replacing with a higher gas price, or 'cancel' by sending a 0-ETH tx to yourself with higher gas using the same nonce.
Is EIP-1559 base fee the same as gas price?
Not quite. Post-EIP-1559, total gas price = base fee + priority fee (tip). Base fee is burned (removes ETH from supply). Priority fee goes to validators as an incentive to include you. During normal conditions, most of your gas cost is base fee.
How much does bridging to Arbitrum or Base actually cost?
Official bridges: $2-8 depending on gas. Third-party bridges like Across or Hop: often $1-3 with faster finality. On Base specifically, the canonical bridge is highly efficient — the round-trip usually pays for itself in 3-5 L2 transactions.
What's the cheapest time of day to transact on Ethereum mainnet?
Weekday nights between midnight and 6 AM UTC consistently show the lowest base fees — often 8-15 gwei versus 40-80 gwei during US and European business hours. Weekend early mornings are also low. Etherscan's gas tracker shows a 7-day heatmap so you can see your target window without guessing.
Why did my transaction fail but I still paid gas?
Gas fees compensate validators for computation, not for successful outcomes. If your transaction runs out of gas mid-execution, reverts due to a contract error, or fails a slippage check on a DEX, the validators still did the work and keep the fee. Failed swap on Uniswap at 35 gwei, 150,000 gas, $3,200 ETH costs $16.80 for nothing. Always set slippage tolerance wide enough to avoid unnecessary reverts, and let your wallet estimate gas rather than setting an artificially low limit.
Does sending ETH to a contract cost more gas than sending to a wallet?
Yes. A plain ETH transfer to an externally owned account (EOA, i.e., a regular wallet) always costs exactly 21,000 gas. Sending ETH to a smart contract triggers the contract's fallback or receive function, which may execute additional logic. That can run 25,000-100,000+ gas depending on the contract. Always confirm you're sending to the right address type before transacting.
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