Bridge transfers need gas on both sides of the transaction

Before bridging tokens from Ethereum, keep enough ETH in the sending wallet to cover the bridge transaction and any required token approval. The bridge moves assets between networks; it does not move the ETH needed to pay for the Ethereum transaction that starts the transfer.

That distinction matters when most of a wallet’s balance is in an ERC-20 token. A transfer can fail before it starts if the wallet cannot pay its Ethereum gas fee, even when the token balance covers the amount being bridged.

How much ETH should you reserve for a bridge?

Reserve the wallet’s displayed maximum fee for every source-chain transaction the route requires, plus a small balance for another transaction if something needs attention. The wallet estimates the gas limit and fee price; the actual fee depends on gas used and the price when the transaction is included.

Check whether the bridge flow asks for an approval before the transfer. A token approval lets a contract spend a specified amount, and it is a separate Ethereum transaction with its own gas cost. Some tokens or prior approvals may mean no new approval is needed, so follow the wallet’s current prompts rather than assuming every route has the same steps.

A fuller walkthrough of the manta bridge flow shows how those steps fit a treasury transfer. The same budgeting principle applies: account for each transaction the route asks the sender to sign.

What does a wallet’s gas estimate tell you?

The gas limit is the maximum computation the transaction can use; the fee price sets how much the sender offers per unit of gas. A higher fee price can help a transaction get included sooner when the network is busy, while the gas limit should match the contract action the wallet is preparing.

For Ethereum transactions using the current fee market, the wallet commonly shows a maximum fee. That is a ceiling, not necessarily the amount charged: unused gas is not billed, and the effective price can be below the maximum fee per unit. Network congestion can change the estimate between checking the quote and signing.

• Confirm the sending network and token contract in the bridge interface.
• Read the wallet’s fee estimate for each approval and transfer prompt.
• Keep enough ETH to cover the displayed maximum for those source transactions.
• Review the destination network’s gas token and keep some there for later actions.

Will the bridge pay gas on the destination network?

Not automatically: paying Ethereum gas starts the source transaction, but a later action on the destination network may require that network’s native gas token. Some routes or services bundle or sponsor parts of the process, so check the bridge quote and transfer status for what is included.

Before signing, compare the quoted amount received with the amount sent and any displayed bridge fee. A bridge may also require a separate claim or follow-up transaction; if so, check whether that action needs destination gas. The practical rule is to fund each network for the steps you expect to perform there, rather than treating one gas balance as covering the full route.

Once the source transaction is confirmed, use the bridge’s status page or transaction details to see whether the transfer is still processing or ready for another step. Keep the destination gas balance available until the tokens arrive and any required claim is complete.