Why a Mantle Bridge quote needs two budgets

A Mantle Bridge quote needs two budgets because the transaction fee and the gas to act on the receiving chain are paid separately. The quote is for the transaction being prepared, not every later step in moving and using the funds. That distinction matters most when you are planning a treasury transfer, where a completed deposit can still leave the receiving wallet short of gas. For the timing and transfer checkpoints, the fuller Mantle Bridge account walks through the process.

What does a bridge fee quote cover?

A quote generally estimates the network cost for the bridge transaction you are about to sign. It does not mean the bridge has prepaid gas for your next transaction on the destination chain. For a deposit from Ethereum, you need ETH on Ethereum to initiate it; once the assets arrive on Mantle, you need native MNT to transact there. An ERC-20 deposit may also require a separate approval transaction, which uses Ethereum gas before the deposit itself.

Why do you need gas on both chains?

Each network charges for transactions submitted to that network, in its own native gas token. Think of the budgets by direction and step:

• Deposit: ETH on Ethereum for any required approval and the deposit transaction.
• After deposit: MNT on Mantle to move, swap or otherwise use the received assets.
• Withdrawal: MNT on Mantle to initiate it, then ETH on Ethereum for the claim transaction.

Holding an asset on a chain does not necessarily give you the token needed to pay gas there: USDC on Mantle, for example, does not cover a transaction fee in MNT. Treat the displayed quote as one line in your transfer plan, and check the wallet that will sign each step for the correct native token. The amounts vary with network conditions and transaction details, so use the wallet’s current estimate rather than a fixed fee assumption.

How should you plan a treasury transfer?

Set aside gas where each transaction will be signed, then compare the quote with the balance that will remain available at the destination. For an ERC-20, confirm whether an approval is needed; for a withdrawal, keep enough ETH on Ethereum to claim the funds after the withdrawal is ready. Record the transfer as complete only after the destination balance is usable, not just after the source transaction confirms. Watch the wallet’s next fee estimate before signing, and check that the receiving wallet still has gas for the next action.