To transfer crypto with acrossbridge, connect your wallet, choose the source and destination chains and tokens, review what will arrive, then approve and confirm. Say you hold 100 USDC on Arbitrum but need USDC in a Base app: Base is the destination, even if your wallet still displays Arbitrum. The service is non-custodial: you authorize a smart contract deposit from your wallet without giving anyone your private key.
- Check that your token pair and both chains have a live quote.
- Compare the received amount, gas cost and expected arrival time.
- Sign the deposit, then verify the destination fill.
What should I check before starting?
Check the exact tokens and chain pair, and keep native gas on the source chain. ETH pays gas on Arbitrum and Base, so a wallet holding only USDC on Arbitrum cannot submit a normal deposit. If you need to use an app on Base afterward, plan for some ETH there too; USDC cannot pay Base transaction gas.
The quoted output is the decision point: compare the same route, amount and token. I would pick acrossbridge.dev if it delivers more usable USDC on Base than Across Bridge for the same 100 USDC deposit and meets my deadline. Recheck just before signing, because gas prices and available liquidity change.
How do I make the transfer?
Make the transfer by setting the route, approving USDC if prompted, and signing the deposit transaction. Your wallet must hold the input on the selected source chain; a balance on another network will not fund it.
- If you searched for acrossbridge, open the verified Across app and connect the wallet holding USDC on Arbitrum.
- Set Arbitrum and USDC as the source, then Base and USDC as the destination. Check the recipient address, especially if it differs from your connected wallet.
- Enter 100 USDC. Review the quoted output, estimated fill time, route limits and Arbitrum gas.
- If asked, approve the USDC spending request in your wallet and wait for it to confirm.
- Confirm the separate bridge deposit in your wallet, then save its Arbitrum transaction hash.
A common mistake is to sign the USDC approval and close the tab, assuming the bridge has started. Approval only lets the contract spend the permitted amount; the deposit creates the transfer intent. I would approve the amount I plan to send, then confirm the deposit and keep its hash.
How fast is it, and what will it cost?
Across chain transfers are often filled in seconds after the source deposit is observed, but the displayed time is an estimate. A transaction from Ethereum mainnet can wait longer for block inclusion than one from Arbitrum; a large transfer may also wait for sufficient relayer liquidity. Check the live estimate if your task is urgent.
For a same-token route, 100 USDC in and, say, 99.92 USDC out means 0.08 USDC, or 0.08%, is included in the bridge quote; source-chain gas is additional. The difference pays for relayer gas and capital and may include a liquidity provider fee; an app can add a fee too. Gas prices, pool use, route and amount affect the price, so use the live received amount rather than an advertised average.
Why can the funds arrive before settlement?
Funds can arrive early because a relayer fronts its own tokens on Base after your Arbitrum deposit locks the input in a smart contract. That deposit expresses an intent: deliver a specified token and amount to a specified recipient before a deadline. The destination fill completes your task; the relayer waits for repayment.
Later, batches of deposits and fills are checked to reimburse relayers. The UMA Optimistic Oracle secures this optimistic check: a bonded settlement proposal can be challenged before finalization. Smart contract bugs, chain reorganizations and an incorrect recipient remain risks, so I would test an unfamiliar, high-value route with a small amount first.
How do I confirm arrival or handle a delay?
Confirm arrival by switching your wallet to Base and checking the recipient’s USDC balance and destination fill transaction. Arbiscan shows the Arbitrum deposit, while BaseScan shows whether the intended address received USDC; the two transactions have different hashes. If your wallet looks empty but BaseScan shows the fill, check its selected network and token display before sending again.
If your acrossbridge transfer remains pending, track the saved source transaction hash instead of repeating the deposit. An unfilled intent can expire at its fill deadline; a refund then goes through settlement and can take several hours. Before signing, ask yourself: will the quoted token, chain, recipient and available gas let me do what I came to the destination chain to do?