When you withdraw from a rollup, finishing on the destination chain can cost extra: an example claim using 200,000 gas at 20 gwei costs 0.004 ETH. The withdrawal amount does not automatically pay that bill. You may need the destination chain’s gas token in your wallet before the funds can arrive.
A withdrawal proof shows that the rollup recorded your exit
A withdrawal proof is evidence that the rollup recorded your request to move funds back to Ethereum. A rollup is a network that processes transactions separately, then records information about them on Ethereum. For example, Mantle Bridge is a way to move supported assets between Mantle and Ethereum.
When you start a withdrawal on Mantle, that transaction records your request on Mantle. The bridge does not usually send the funds to Ethereum in that same moment. Instead, the request must be included in rollup data that Ethereum can check.
A proof often works like a receipt with a cryptographic seal. It shows that your withdrawal is part of the recorded data. Ethereum.org explains how rollups use proofs to check transactions; the exact proof and waiting rules depend on the bridge’s design.
The recipient pays to submit the proof and claim funds
The destination chain needs a transaction to check the proof and release the funds. A person or service submits that transaction, and someone pays its network fee. If you submit it yourself, you pay the fee from your wallet on Ethereum.
That fee is called gas: payment for the computing work a blockchain performs. On Ethereum, gas is paid in ETH. So a withdrawal of MNT or another token can still require ETH in the receiving wallet.
Some bridges or relayers submit the final transaction for you. A relayer is a service that sends a transaction on your behalf; its cost may be covered by the bridge or included in its terms. Check who pays before you assume the recipient gets a fee-free transfer.
A small example shows why the destination balance matters
Suppose you withdraw 100 MNT from Mantle to Ethereum. For illustration, imagine the proof and claim together use 200,000 gas, and Ethereum’s gas price is 20 gwei. One gwei is one-billionth of an ETH, so the example fee is 200,000 × 20 gwei, or 0.004 ETH.
This is an example, not a current quote. Actual gas use depends on the contract calls; the gas price changes with Ethereum demand. If the transaction needs two separate steps, such as proof submission and final claim, each may need its own Ethereum transaction and fee.
The key edge case is a wallet that receives ETH as its withdrawal but has no ETH before the claim. The withdrawn ETH may be locked until the claim succeeds, so it cannot pay for the transaction that releases it. Arrange a small ETH balance on Ethereum first, or confirm that the bridge or a relayer covers the claim cost.
Check the fee payer before starting
Before withdrawing, confirm which wallet address will receive the funds and whether that wallet can pay Ethereum gas. Also check whether the bridge requires a separate proof and claim, and whether a waiting period applies. Mantle’s official repository identifies its bridge as the route between Mantle and Ethereum; the live bridge’s settlement rules determine the exact steps.
If the recipient can cover destination gas and wait for settlement, a direct withdrawal can work; if not, use a route with a clearly stated relayer or fee arrangement.