How to bridge ETH to Layer 2: Arbitrum, Optimism and Base explained

Bridging ETH means moving your ETH from Ethereum Mainnet to a Layer 2 network such as Arbitrum, Optimism or Base. Layer 2 networks process transactions faster and at a fraction of the cost of Mainnet. A simple token swap that costs $20 on Mainnet costs under $0.50 on Arbitrum and under $0.30 on Base. This guide covers what a Layer 2 bridge is, how to add each network to MetaMask, step-by-step instructions for bridging ETH to all three networks, how to withdraw back to Mainnet, and the most common mistakes to avoid.

What is a Layer 2 bridge?

A Layer 2 bridge is the mechanism that moves ETH between Ethereum Mainnet and a Layer 2 network. When you bridge ETH, your ETH is not actually transferred anywhere. It is locked in a smart contract on Mainnet, and an equivalent amount of ETH is issued on the L2 network for you to use. When you bridge back, the L2 version is burned and your original ETH is released from the Mainnet contract.

Arbitrum, Optimism and Base are all optimistic rollups. They process transactions off Mainnet in batches and post compressed data back to Ethereum. Because they inherit Ethereum security, the funds on these networks are protected by the same proof-of-stake consensus that secures Mainnet itself. The difference between Mainnet and these networks is cost: Mainnet gas fees run roughly $5-50 per transaction, while Arbitrum and Optimism average $0.10-0.50, and Base averages $0.05-0.30. The full mechanics of how Ethereum validates and records transactions are covered in the guide on how Ethereum works.

Arbitrum, Optimism and Base compared

The three networks share the same rollup architecture but differ in focus, fee levels and who they suit best. Before bridging, check which network fits your use case.

The chain IDs you need when adding these networks to your wallet are: Arbitrum One: 42161, Optimism: 10, Base: 8453. A note on Base: the original bridge at bridge.base.org was deprecated in September 2025. Do not use it. The options covered below are the current working alternatives.

For DeFi users who need deep liquidity, Arbitrum is the default choice. For users who already hold funds on Coinbase or want the lowest gas fees, Base is the better starting point. Optimism is strongest for users building on OP Stack chains or those who prefer the Superchain network of connected L2s. The underlying proof-of-stake mechanism that secures all three is explained in the guide on Ethereum proof of stake.

What you need before you bridge

Before you bridge ETH to any Layer 2, make sure you have the following in place.

• A Web3 wallet. MetaMask is the most widely supported option. Coinbase Wallet and Rainbow also work with all three networks covered here.
• ETH in your wallet, not on an exchange. Bridge interfaces connect to your wallet directly. ETH sitting on Coinbase or Binance cannot be bridged until you withdraw it to your wallet first.
• Extra ETH for gas on Mainnet. The bridge transaction itself costs a gas fee paid from your Mainnet balance. Never bridge your entire ETH balance. Leave at least 0.005 ETH in your wallet to cover the gas fee.
• The destination network added to MetaMask. Your wallet needs to know about the network you are bridging to before it can display your balance there. The next section covers exactly how to do this.
• Verified bridge URLs bookmarked. Phishing sites copy the exact appearance of bridge interfaces. Always navigate to the bridge directly and bookmark the URL rather than relying on search results.

One additional tip before bridging larger amounts: send a test transaction first. Bridge 0.005 ETH as a test run before committing a larger amount. The process is identical regardless of size, and a test confirms that your wallet setup and network configuration are correct. The guide on how to buy Ethereum covers acquiring ETH if you do not have any yet.

Native bridge vs third-party bridge: which should you use?

There are two categories of bridge for moving ETH to Layer 2: native bridges operated by the network itself, and third-party bridges such as Across Protocol and Hop Protocol. Each has different tradeoffs for speed, cost and security.

Use the native bridge when you are moving amounts above $10,000 and want the highest possible security. Use a third-party bridge such as Across or Hop when you need funds on L2 quickly, or when withdrawing back to Mainnet and do not want to wait seven days. For a first-time bridge, third-party options are easier to use and faster to confirm.

The main third-party options in 2026 are Across Protocol (across.to) for the fastest transfers, typically 18 seconds L1 to L2. Hop Protocol (hop.exchange) for strong liquidity and reliable fast withdrawals, and Orbiter Finance (orbiter.finance) for L2-to-L2 routes. All three are non-custodial: your private keys never leave your wallet.

Bridging mistakes to avoid

Most problems with bridging ETH come from a small number of avoidable errors. The seven below cover the ones users encounter most often.

• Selecting the wrong destination network. The most common mistake. Confirm both the From and To chain selections before clicking Confirm. If you send ETH to the wrong network, you will need to bridge again to reach the intended destination, paying another gas fee.
• Bridging from an exchange account instead of a wallet. Exchanges hold ETH on their own internal systems. Sending from an exchange directly to a bridge interface does not work and can result in stuck or lost funds. Always withdraw from the exchange to MetaMask first, then bridge.
• No ETH on the destination chain after arrival. When you first arrive on a new Layer 2, you have ETH but no transaction history. If you bridge exactly the amount you want to use, you may not have enough left to pay for transactions. Bridge slightly more than you need.
• Not enough ETH for gas on the source chain. The bridge deposit itself costs a gas fee paid from your source chain balance. If you try to bridge your entire ETH balance, the transaction will fail because there is nothing left for gas. Always keep at least 0.005 ETH in reserve.
• Using a deprecated bridge URL or a phishing site. Bridge interfaces are frequently copied by phishing sites. The original Base bridge at bridge.base.org no longer works. Always navigate to bridge URLs directly and bookmark them. Do not click bridge links in search ads or social media messages.
• Confusing token addresses across networks. Your wallet address (0x…) is the same on all EVM networks. Token contract addresses are not. USDC on Arbitrum has a different contract address than USDC on Optimism. Use the bridge interface to handle the correct token rather than copying contract addresses manually. The process of transferring ETH between addresses on the same network is explained in the guide on how to transfer Ethereum.
• Resubmitting a pending transaction. Bridge deposits can take 15-30 minutes. If a transaction shows as pending, wait. Submitting the same transaction again does not speed it up and may result in a duplicate charge. Track progress on Etherscan using your wallet address.

Is it safe to bridge ETH?

Bridging ETH to Arbitrum, Optimism or Base through their official native bridges is considered low-risk within the crypto space. These bridges are operated by the same teams that run the networks, inherit Ethereum security directly, and have been running without major incidents since their respective launches.

Third-party bridges such as Across Protocol and Hop Protocol are non-custodial: your private keys never leave your wallet and the bridge contracts hold funds only in transit. Both protocols have been independently audited multiple times. The main risk with any smart contract is a bug that was not caught in the audit, but this risk is lower for established, heavily used protocols than for new or unaudited ones.

All three Layer 2 networks include an escape hatch mechanism. Even if a Layer 2 sequencer stops operating, users can submit withdrawal transactions directly to Ethereum Mainnet without relying on the L2 at all. Funds on Arbitrum, Optimism or Base are not permanently stuck if the L2 goes offline.

The bridge hacks that made headlines (Ronin, Wormhole, Nomad) were cross-chain bridges connecting entirely separate blockchain network of protocolss, not native Layer 2 bridges of the type covered here. Native L2 bridges route through Ethereum itself and do not rely on external validator sets or multisig arrangements in the same way. The smart contract architecture that underpins both bridging and Layer 2 security is covered in the guide on the Ethereum Virtual Machine.

FAQ

How long does it take to bridge ETH to Layer 2?

Using a native bridge such as the Arbitrum Bridge or Optimism bridge, deposits from Mainnet to Layer 2 take 15-30 minutes. Using a third-party bridge such as Across Protocol, the same deposit takes 18 seconds to 2 minutes. L2-to-L2 transfers on Across typically complete in around 3 seconds. The time depends on Mainnet congestion and which bridge you use.

How much does it cost to bridge ETH?

The deposit fee is made up of the Mainnet gas cost to initiate the bridge transaction, typically $2-10 depending on congestion, plus any bridge-specific fee. Third-party bridges add a relayer fee of roughly $0.50-3. On average, bridging ETH from Mainnet to Arbitrum or Optimism costs $2-8 total. Bridging to Base costs slightly less because it is built on more efficient infrastructure. L2-to-L2 transfers avoid Mainnet gas and cost under $1 in most cases.

Can I bridge ETH directly from an exchange?

No. Bridge interfaces connect to your Web3 wallet, not to an exchange account. To bridge ETH, first withdraw it from the exchange to your MetaMask wallet on Ethereum Mainnet, then use the bridge. Some exchanges such as Coinbase allow direct withdrawals to Base, which bypasses the need to bridge at all for that specific network. If you need to convert bridged ETH back to fiat, the guide on how to sell Ethereum covers the full process from wallet to bank account.

What happens if I bridge to the wrong network?

Your ETH will arrive on the wrong Layer 2 network rather than the intended one. It is not lost. You can bridge it again from the wrong network to the correct destination, or bridge it back to Mainnet and start over. Both options cost additional gas fees. To avoid this, always double-check the From and To chain selections on the bridge interface before confirming.

Why does withdrawing from Layer 2 take 7 days?

Arbitrum and Optimism are optimistic rollups. They assume all transactions are valid and post them to Ethereum without verifying each one individually. The 7-day window exists so that anyone who spots a fraudulent transaction has time to submit a fraud proof and challenge it. Once the window closes with no challenge, the withdrawal is finalised on Mainnet. Third-party bridges like Hop Protocol bypass this wait by using liquidity providers who complete the exit immediately.

What is the fastest way to bridge ETH?

Across Protocol is the fastest option for bridging ETH from Mainnet to Layer 2, completing most transfers in around 18 seconds. For L2-to-L2 transfers, Across completes in approximately 3 seconds. Hop Protocol is also fast for withdrawals back to Mainnet. Both are non-custodial and audited. Speed comes at the cost of a slightly higher fee compared to native bridges, but for most amounts the difference is under $2. The original decision to design Ethereum as a settlement layer that L2 networks could build on is explained in the guide on who created Ethereum.

Do I need ETH on the destination chain to start using it?

No. You do not need any ETH on a Layer 2 before bridging to it. The ETH you bridge becomes your starting balance on that network and is used to pay gas fees for subsequent transactions. This is why it is important not to bridge your exact intended amount. Bridge slightly more so you have enough ETH left to pay for the transactions you want to make.

Is MetaMask the only wallet I can use for bridging?

No. Any EVM-compatible Web3 wallet works with the bridges covered in this guide. Coinbase Wallet, Rainbow and WalletConnect-compatible wallets all support Arbitrum, Optimism and Base. MetaMask is the most widely tested option and the one most bridge interfaces list first, but it is not the only choice. All wallets use the same wallet address format and the same network settings covered in this guide.