How to Bridge from Ethereum Mainnet to Arbitrum One
Bridging from Ethereum Mainnet to Arbitrum One moves your assets from Ethereum's base layer into Arbitrum's optimistic rollup, where transactions settle faster and cost less. You do this by locking assets in a smart contract on Ethereum and receiving a representation of them on Arbitrum. The official process uses Arbitrum's native bridge, which is the most reliable method for most users.
What the bridge actually does
Arbitrum One is a Layer 2 network that posts transaction data to Ethereum but executes transactions off-chain. To use it, you need funds on Arbitrum's side. The native bridge locks your Ether (ETH) or ERC-20 tokens in a contract on Ethereum and mints an equivalent amount on Arbitrum. When you want to move back, the reverse happens: tokens are burned on Arbitrum and unlocked on Ethereum. This is a one-to-one process - no exchange rate or slippage, though you pay gas on both chains.
Prerequisites
Before you start, make sure you have:
- An Ethereum wallet (MetaMask, Rabby, or any wallet that supports Arbitrum) with enough ETH to cover gas fees on Ethereum Mainnet - typically $10 - $50 worth depending on network congestion.
- The Arbitrum One network added to your wallet. Most wallets auto-detect it, but you can add it manually using chain ID 42161 and the RPC URL from Arbitrum's documentation.
- The asset you want to bridge (ETH or an ERC-20 token that Arbitrum supports). Check the bridge interface for supported tokens.
Step-by-Step: Bridging with the Native Bridge
1. Open the Arbitrum Bridge
Go to bridge.arbitrum.io. Connect your wallet. The interface will show your Ethereum balance and a destination address (your same wallet on Arbitrum). Confirm the destination is correct - sending to the wrong address is irreversible.
2. Select Your Asset and Amount
Choose the token you want to bridge from the dropdown. Enter the amount. The interface will estimate the gas cost on Ethereum and show the expected time for the transaction to complete (usually a few minutes). Note that bridging ERC-20 tokens may require a separate approval transaction first - this is a standard Ethereum token approval that lets the bridge contract spend your tokens.
3. Initiate the Deposit
Click "Move funds to Arbitrum One". Your wallet will prompt you to confirm a transaction on Ethereum Mainnet. This transaction sends your assets to the bridge contract. Gas fees here are paid in ETH on Ethereum and can vary. Once confirmed, the bridge waits for enough Ethereum block confirmations (typically 12 - 15 blocks, about 3 - 5 minutes) to consider the deposit final.
4. Claim on Arbitrum
After the deposit is confirmed, the bridge automatically mints the equivalent tokens on Arbitrum. In most cases, they appear in your wallet within minutes. If they don't, you may need to click a "Claim" button in the bridge interface - this happens rarely but is possible during network congestion. The claiming transaction itself costs a small amount of gas on Arbitrum (paid in ETH on Arbitrum, which you receive as part of the bridge).
Speed and Costs
The deposit from Ethereum to Arbitrum takes about 5 - 15 minutes total. Cost consists of:
- Ethereum gas: The main expense. At average Ethereum fees, bridging $100 of ETH might cost $15 - $30 in gas. This is fixed regardless of the amount you bridge, so larger transfers are more cost-efficient.
- Arbitrum gas: Negligible (often under $0.10) for the claiming step.
The withdrawal (moving back to Ethereum) is slower - typically 7 - 8 days due to Arbitrum's optimistic fraud proof window. If you need faster withdrawals, consider a third-party bridge (covered elsewhere on this site) that may offer instant exits at a premium.
What can go wrong
- Wrong network: If you send to a wallet address on a different chain (e.g., Optimism), the funds are lost. Double-check the destination network.
- Unsupported token: Some tokens exist on Ethereum but not on Arbitrum. The bridge will reject them. Check Arbitrum's token list before starting.
- Gas spikes: If Ethereum gas prices spike during your deposit, the transaction might stall. You can speed it up by replacing the transaction with a higher gas price, or wait. The bridge will eventually process it.
- Pending too long: If more than an hour passes with no confirmation, check your wallet's transaction history. You may need to cancel and retry.
When to Use the Native Bridge
Use the native bridge when:
- Security is your priority. The native bridge is directly maintained by the Arbitrum team and relies on the same fraud proof system that secures the rollup.
- You are moving large amounts (over $1,000). The gas cost is fixed, so percentage fees drop with size.
- You are not in a hurry. The deposit is fast, but the return trip is slow.
For small amounts or urgent moves, consider a third-party bridge that might offer faster withdrawals or lower gas costs - but review those trade-offs in the native bridge vs third-party bridge comparison on this site.
After Bridging
Once your funds arrive on Arbitrum, you can use them on any dApp that supports the network - decentralized exchanges, lending protocols, or NFT marketplaces. To check your balance, switch your wallet to the Arbitrum One network. To move funds back to Ethereum, reverse the process through the same bridge interface, but expect the 7-day wait.
Not financial advice. mycoin.hk publishes market data and general information about digital assets. Crypto assets are volatile and you can lose everything you put in. Nothing here is a recommendation to buy, sell or hold, and we make no price predictions.
Prices are sourced from third parties and may be delayed or wrong. Verify anything you intend to act on against a primary source.