L2 Gas Fees: Live Comparison

What is a Layer 2, and why use one?

Ethereum mainnet is secure but expensive. A Layer 2 is a separate chain that settles back to Ethereum, giving you mainnet-level security at a fraction of the cost. Rollups (Arbitrum, Optimism, Base) batch transactions and post compressed proofs to L1. Sidechains (Polygon PoS) run their own consensus and checkpoint to Ethereum periodically. Either way, you pay cents or less for an operation that would cost dollars on mainnet.

How to pick the right L2

• For routine DeFi: any major L2 works. Pick the cheapest with the app you need.
• For Coinbase users: Base wins — free direct withdrawals from Coinbase, no bridge round-trip.
• For deep liquidity: Arbitrum has the largest L2 TVL — most depth for big swaps.
• For OP-native apps: Optimism hosts Velodrome and other native venues with tuned gas usage.
• For tiny fees and gaming/NFTs: Polygon PoS has near-zero gas and stays cheap even when Ethereum is congested.

The two-part fee model — why rollup costs track mainnet

Every rollup transaction pays for two things: L2 execution (running the EVM on the sequencer) and L1 data posting (publishing the transaction to Ethereum so it inherits L1 security). Execution is a few cents on a quiet day. Data posting is what moves with mainnet base fee — and on most days, it dominates the bill.

• OP Stack (Base, Optimism): the estimate on this page includes both components — L2 execution gas plus the L1 data fee, queried live from the GasPriceOracle predeploy at 0x420…00F. The L1 portion (sized from calldata) is why a Base/Optimism wallet fee is more than “L2 gas price × gas limit” — and it's already folded into the figure shown.
• Arbitrum Nitro: folds the L1 calldata fee directly into eth_gasPrice. What your wallet shows is what you pay — no separate L1 fee. This makes Arbitrum quotes simpler but means the displayed gas price spikes when mainnet does.
• Polygon PoS: not a rollup. No L1 data posting on each transaction (only periodic checkpoints). Fees are paid in POL/MATIC and stay near-zero regardless of mainnet conditions.

EIP-4844 (Dencun, March 2024) introduced blob-carrying transactions and dropped the L1 data cost for rollups by 10-20x. Every rollup in the table above adopted blobs within weeks. The effect: rollup fees stayed cheap through every mainnet congestion event since — even when mainnet base fee hit triple digits. The next upgrade (PeerDAS) will scale blob throughput further; expect another step-function reduction in rollup costs when it ships.

Withdrawal timing — the L2's hidden cost

L2 gas fees are only part of the story. Withdrawing back to mainnet via the native bridge is where the time cost shows up:

• Arbitrum: ~1 hour for the rollup to finalize, then ~7 days for the optimistic challenge period before you can claim on L1.
• Optimism / Base: also ~7-day challenge window. The exact period depends on the chain's fault-proof parameters; expect ~6 days, 22 hours.
• Polygon PoS: 30-90 minutes for a checkpoint, plus the L1 finalization transaction.

If you need to exit faster, paid bridges (Across, Stargate, Hop) front the withdrawal for a fee — usually 0.05-0.15% on stablecoins, often higher on volatile tokens. They're much faster than the native bridge (minutes vs days) but more expensive than depositing in the first place. See cheapest bridge to Base for current rates.

Mainnet vs L2 — when to stay on Ethereum

L2s win for most active use, but mainnet is still right when you need composability with mainnet-only contracts, are depositing to a centralized exchange that does not support L2 withdrawals, or moving very large value where the bridge round-trip plus L2 finality wait exceeds the fee savings. See the live Ethereum mainnet gas fees and full guide to reducing mainnet gas.

Frequently asked questions