Moving assets from Ethereum’s mainnet to Arbitrum is one of the most common actions in DeFi today, and for good reason: Arbitrum offers dramatically lower gas fees and faster finality while inheriting Ethereum’s security model. If you hold ETH or ERC-20 tokens in MetaMask and want to access Arbitrum’s ecosystem of protocols, you need to bridge — but the process has a few steps that trip up newcomers. This guide walks you through exactly how to bridge Ethereum to Arbitrum using MetaMask, covering the official bridge, what fees to expect, how long it takes, and what can go wrong.
What “Bridging” Actually Means
A bridge is a smart-contract system that locks or burns tokens on one chain and mints equivalent tokens on another. When you bridge ETH from Ethereum mainnet to Arbitrum One, you are not “moving” the same tokens — you are locking ETH in a contract on Layer 1 and receiving a corresponding representation of ETH on Arbitrum’s Layer 2 network.
Arbitrum One is an optimistic rollup. According to the Arbitrum developer documentation, deposits (L1 → L2) typically finalize within roughly 10–15 minutes, while withdrawals (L2 → L1) are subject to a 7-day challenge period under the optimistic rollup security model. Third-party fast-exit services can shorten that withdrawal window, but they introduce counterparty risk.
What You Need Before You Start
- MetaMask installed — browser extension or mobile app, version current as of 2026. Download only from metamask.io (official site listed in the MetaMask documentation).
- ETH on Ethereum mainnet — you need ETH both as the asset you want to bridge and to pay the Layer 1 gas fee for the deposit transaction.
- Arbitrum One network added to MetaMask — instructions below.
- A basic understanding that L1 gas fees apply even for bridging small amounts; during high congestion these can exceed $5–$20 or more.
Step 1: Add Arbitrum One to MetaMask
MetaMask does not include Arbitrum One by default in older installations. You have two reliable ways to add it.
Option A — Via Chainlist
Chainlist (chainlist.org) aggregates verified RPC data from the ethereum-lists/chains repository on GitHub. Connect your MetaMask wallet on Chainlist, search for “Arbitrum One” (Chain ID 42161), and click “Add to MetaMask.” Confirm the network details in the MetaMask prompt.
Option B — Manual Entry
In MetaMask, go to Settings → Networks → Add a Network and enter these values as published in the Arbitrum developer documentation:
- Network Name: Arbitrum One
- New RPC URL: https://arb1.arbitrum.io/rpc
- Chain ID: 42161
- Currency Symbol: ETH
- Block Explorer URL: https://arbiscan.io
Step 2: Use the Official Arbitrum Bridge
The canonical bridge for Arbitrum is the Arbitrum Bridge, accessible at bridge.arbitrum.io — this is the URL listed in the official Arbitrum Foundation documentation and is the only bridge that settles against the core Arbitrum rollup contracts directly.
Connecting Your Wallet
- Navigate to bridge.arbitrum.io.
- Click “Connect Wallet” and select MetaMask.
- Approve the connection request in the MetaMask pop-up. Ensure MetaMask is set to Ethereum Mainnet before connecting.
Initiating the Deposit
- In the “From” field, confirm it shows Ethereum Mainnet. In the “To” field, confirm Arbitrum One.
- Select the token you want to bridge (ETH is shown by default; ERC-20 tokens appear after you search or paste a contract address).
- Enter the amount. The interface will display an estimated L1 gas fee in ETH.
- Click “Move funds to Arbitrum One.”
- MetaMask will open a transaction confirmation window. Review the gas fee carefully — do not lower the gas limit below what MetaMask estimates, as this can cause the transaction to fail.
- Click “Confirm.”
Waiting for Finality
Your transaction will appear as pending on Etherscan while the L1 transaction confirms. Once the L1 transaction is mined, Arbitrum’s sequencer processes the deposit. The Arbitrum developer documentation states that L1-to-L2 message execution is generally automatic, but in rare cases you may need to manually redeem the transaction via the bridge interface using the “Retryable Tickets” section.
Step 3: Verify Your Balance on Arbitrum
Once the deposit is processed, switch MetaMask to the Arbitrum One network. Your ETH balance should reflect the bridged amount. For ERC-20 tokens, you may need to add the token contract address to MetaMask manually. Token contract addresses for Arbitrum can be verified on Arbiscan (arbiscan.io), Arbitrum’s official block explorer.
Fees and Tax Implications to Know
Bridging is not free or tax-neutral. There are two cost categories to understand.
Gas Fees
You pay an L1 Ethereum gas fee when depositing. This fee fluctuates with mainnet congestion and is denominated in ETH. There is no additional protocol fee from Arbitrum itself for canonical deposits. When bridging back (withdrawing), you pay a small L2 gas fee (typically fractions of a cent) to initiate the withdrawal, plus an L1 gas fee to claim your funds after the 7-day challenge window.
Tax Considerations
The IRS has not issued specific guidance on bridge transactions as of 2026. However, under IRS Notice 2014-21 and the broader framework of crypto as property, the gas fees you pay on-chain in ETH may be considered a disposal of that ETH, potentially a taxable event. Some tax professionals treat a bridge as a non-taxable transfer since you receive a 1:1 representation of the same asset. You should document every bridge transaction — including timestamps, amounts, and gas costs — and consult a tax professional familiar with crypto. Tools like Koinly and CoinTracker can import transaction history from both Ethereum and Arbitrum.
Common Problems and How to Fix Them
- Transaction stuck as pending: If the L1 transaction is underpriced, it may sit in the mempool. Use MetaMask’s “Speed Up” feature to resubmit with a higher gas price.
- Funds not visible on Arbitrum: Wait the full 15 minutes, then check the Arbitrum Bridge interface under “Transaction History.” If a retryable ticket failed, you can manually redeem it there.
- Wrong network selected: If MetaMask is on Arbitrum One when you initiate the deposit, the bridge UI should warn you. Always double-check the “From” chain before confirming.
- Token not appearing in MetaMask: Add the Arbitrum token contract manually using the address verified on Arbiscan.
What This Means for You
Bridging Ethereum to Arbitrum using MetaMask is a straightforward process when you use the official Arbitrum Bridge and take time to verify network details before confirming transactions. The deposit direction (Ethereum → Arbitrum) is fast and inexpensive relative to most L1 actions. The withdrawal direction is slower due to the 7-day challenge period inherent to optimistic rollups — plan accordingly if you know you will need funds back on mainnet within a week. Always verify URLs against official documentation, never bridge through a link you received via DM or social media, and keep a record of your transactions for tax purposes.
