Gas & Costs on Ethereum

What You Probably Got Wrong

Your gas estimate is 100-600x too high. Most LLMs confidently state gas is 10-30 gwei. Post-Fusaka (Dec 2025), typical base fee is under 1 gwei — usually 0.1-0.5 gwei. Verify: cast base-fee --rpc-url https://eth.llamarpc.com

• Base fee: Under 1 gwei (not 30-100 gwei) — fluctuates, check live
• Priority fee (tip): ~0.01-0.1 gwei
• ETH price: ~$2,000 (not $2,500-3,000) — volatile, always check a Chainlink feed or CoinGecko

What Things Actually Cost (Early 2026)

Costs calculated at ETH ~$2,000. Gas fluctuates — use cast base-fee for current. These are order-of-magnitude guides, not exact quotes.

Mainnet vs L2 Costs (Early 2026)

Key insight: Mainnet is now cheap enough for most use cases. L2s are 5-10x cheaper still.

Why Gas Dropped 95%+

1. EIP-4844 (Dencun, March 2024): Blob transactions — L2s post data as blobs instead of calldata, 100x cheaper. L2 batch cost went from $50-500 to $0.01-0.50.
2. Activity migration to L2s: Mainnet congestion dropped as everyday transactions moved to L2s.
3. Pectra (May 2025): Doubled blob capacity (3→6 target blobs).
4. Fusaka (Dec 2025): PeerDAS (nodes sample 1/8 of data) + 2x gas limit (30M→60M).

L2 Cost Components

L2 transactions have two cost components:

1. L2 execution gas — paying the sequencer
2. L1 data gas — paying Ethereum for data availability (blobs post-4844)

Example: Swap on Base

• L2 execution: ~$0.0003
• L1 data (blob): ~$0.0027
• Total: ~$0.003

Real-World Cost Examples

Deploy a production ERC-20 on mainnet: ~$0.50 (was $200-500 in 2021-2023)

DEX aggregator doing 10,000 swaps/day:

• Mainnet: $150/day ($4,500/month)
• Base L2: $10/day ($300/month)

NFT collection mint (10,000 NFTs):

• Mainnet: $150 total
• Arbitrum: $10 total

Practical Fee Settings (Early 2026)

// Rule of thumb for current conditions
maxFeePerGas: "1-2 gwei"          // headroom for spikes (base is usually 0.1-0.5)
maxPriorityFeePerGas: "0.01-0.1 gwei"   // enough for quick inclusion

Spike detection:

const feeData = await provider.getFeeData();
const baseFee = Number(feeData.maxFeePerGas) / 1e9;
if (baseFee > 5) console.warn(`Gas spike: ${baseFee} gwei. Consider waiting.`);

Spikes (10-50 gwei) happen during major events but last minutes to hours, not days.

Checking Gas Programmatically

# Foundry cast
cast gas-price --rpc-url https://eth.llamarpc.com
cast base-fee --rpc-url https://eth.llamarpc.com

When to Use Mainnet vs L2

Use mainnet when: DeFi, governance, identity, high-value transfers, composing with mainnet liquidity, or when you don't have a concrete reason for an L2. Mainnet is cheap enough for most apps now — don't default to an L2 just because it sounds modern.

Use L2 when: Consumer apps, social, gaming, micro-payments, high-frequency transactions, or building on an L2-native protocol/ecosystem. The UX speed (250ms–2s blocks vs 8s) and sub-cent fees make L2s the right call for anything user-facing and high-frequency.

Hybrid: Many projects store value on mainnet, handle transactions on L2.

Live Gas Trackers

• https://etherscan.io/gastracker
• https://ultrasound.money
• L2 costs: Arbiscan, Basescan, etc.

Data Freshness

Last verified: 2026-03-17 | Base fee: ~0.05 gwei | ETH: ~$2,329 | Gas limit: 60M (post-Fusaka)

If this date is more than 30 days old, verify current gas with:

cast base-fee --rpc-url https://eth.llamarpc.com

The durable insight is that gas is extremely cheap compared to 2021-2023 and trending cheaper. Specific numbers may drift but the order of magnitude is stable.

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