Formiga.

Chapter · Master Base

Bridging to Base

Your ETH does not automatically live on Base. To move value from Ethereum to Base, you use a bridge. A bridge is a tool that locks your asset on Ethereum and gives you a matching amount on Base. When you want to go back, the process reverses. Many people skip the bridge entirely by withdrawing straight from a Coinbase account to Base, which is often the easiest path. Either way, the key idea is that funds have to cross over before you can spend them on Base.

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What this lesson covers

The withdrawal wait

Moving from Ethereum to Base is quick. Going the other way, from Base back to Ethereum through the official bridge, can be slow. Because Base is an optimistic rollup, there is a challenge window where withdrawals wait so anyone can dispute a bad batch first. On the official bridge this waiting period is about seven days. Many people avoid the wait by using third-party bridges or by withdrawing to a Coinbase account, but the official route trades speed for extra safety.

What you get asked

  1. What does a bridge do?

    A bridge locks your asset on the source chain and issues a matching amount on the destination chain, so value moves without being copied twice.

  2. Put the deposit-to-Base steps in order.

    Bridging into Base locks your ETH on Ethereum and hands you a matching balance on Base, which you can then spend on the network.

  3. About how many days is the challenge window for an official withdrawal from Base back to Ethereum?

    The optimistic rollup design uses roughly a seven day challenge window on the official bridge, which lets people dispute invalid withdrawals before they finalize.

  4. Why does an official withdrawal from Base to Ethereum take time?

    Optimistic rollups keep a challenge window so invalid withdrawals can be caught. That safety step is why the official exit takes about a week.

The rest of this chapter

Learn how Base works as Coinbase's Ethereum Layer 2, from rollups and the OP Stack to gas in ETH, bridging, the sequencer, and staying safe.