Bridge from Arbitrum to Optimism

Mechanically, not much: both are optimistic-rollup L2s that use ETH for gas, confirm in the low seconds, and keep fees around a few cents. What changes is the app layer around your funds. Arbitrum concentrates the deepest L2 DeFi liquidity, with GMX, Uniswap, and a heavy perpetuals scene, while Optimism anchors the Superchain and leans on Velodrome plus its retroactive public-goods funding culture. Most people cross because a specific pool, incentive, or app they want sits on OP Mainnet, not because one chain is technically better than the other.

Optimism uses ETH for gas, the same asset Arbitrum uses, so you don't need a new gas token. But if you bridge only a stablecoin like USDC, you can arrive with a balance you can't move because there's no ETH to pay the fee. Many liquidity bridges let you request a small amount of destination ETH as part of the transfer, and it's worth keeping a few dollars of ETH on OP Mainnet regardless. Gas there is usually a couple of cents, so a little stretches a long way.

Optimism carries both a native, Circle-issued USDC and an older bridged version often labeled USDC.e. Which one you receive depends on the route the bridge takes, and the two aren't always interchangeable inside a given app. If you're heading to a specific Velodrome pool or protocol, check which USDC it expects before you send, and pick a route that delivers that one.

A liquidity bridge quoting Arbitrum to Optimism usually settles well under a few minutes, since it fills you from a pool on the destination side rather than waiting on the rollup's own exit. Optimism's native withdrawal path, like other optimistic rollups, carries a challenge window that can run up to roughly a week before funds finalize — fine for large, patient moves, slow for everyday transfers. Times can still stretch during congestion or when a bridge rebalances liquidity, so treat any quoted estimate as approximate.

You'll pay three things: gas to send on Arbitrum, the bridge's fee or spread, and gas to receive on Optimism. Both legs run on L2s where gas is typically only a few cents, so the bridge fee is usually the largest line. On small transfers that fee can be a meaningful share of the amount, so it's worth comparing a couple of routes before you confirm.

Start with a small test amount before sending the full balance, especially the first time on a given bridge or aggregator. Confirm you're on the correct site, that the source chain reads Arbitrum One and the destination reads OP Mainnet, and that the token and receiving address are right. Sticking to well-known aggregators that quote multiple routes tends to give better pricing and a clearer picture of what you'll actually receive. As of publication, reputable liquidity bridges handle this L2-to-L2 pair routinely, but the usual on-chain caution still applies.