Keep some ETH on both networks because fees are paid separately from the USDT you move. ETH pays for the Ethereum transaction and, later, for actions on Manta Pacific.
What does “gas” mean during a token transfer?
Gas is the fee for having a network process an action. On Ethereum, a token transfer through a bridge may involve more than one action, such as approving a contract to use your USDT and then sending the bridge transaction.
An approval is a wallet permission for a contract to move a set amount of your tokens. It does not move the USDT by itself, and it can require its own Ethereum fee. Ethereum’s transaction documentation explains that actions involving smart contracts require gas.
For the full transfer flow, read how Manta Bridge moves assets. This article focuses on planning for fees, so you can avoid having the right token but too little ETH to complete an action.
Why can’t USDT pay the fee?
USDT is a token, while ETH is the asset used to pay network fees on Ethereum and Manta Pacific. Holding enough USDT for the transfer does not guarantee that your wallet can pay the fee to approve or send it.
Think of the fee as separate from the amount you want to move. If you plan to bridge 100 USDT, you need enough USDT for that transfer and enough ETH in your Ethereum wallet for any required approval and bridge transactions.
The OP Stack documentation describes token bridges as cross-network transfers that use smart contracts. That helps explain why sending a token can involve contract actions, even when the amount and destination look simple in a wallet.
How much ETH should you leave on each network?
There is no single amount that fits every transfer. Ethereum fees change with network demand, and the amount of ETH needed on Manta Pacific depends on the actions you plan to take after the USDT arrives.
Before sending, check the fee estimate shown by your wallet for each Ethereum action. Keep that estimated amount available in ETH, with a little extra in case the estimate changes before the transaction is included. Do not treat the entire ETH balance as available to bridge if that would leave too little for the fee.
For example, imagine you have 0.02 ETH and want to move USDT. Your wallet shows that approval and the bridge transaction together may use 0.004 ETH. That estimate is only an example: check your wallet at the time, then keep enough ETH for those actions instead of trying to send the full balance.
Also plan for the destination. If you receive USDT on Manta Pacific and want to send it, swap it, or use it in an app, you will need ETH there to pay for those transactions. The incoming USDT cannot pay that fee for you.
What should you check before using Manta Bridge?
Before using Manta Bridge, make sure the wallet has ETH on Ethereum for the transfer’s source-side fees. If you want to use the USDT after it arrives, plan to have ETH available on Manta Pacific too.
A failed or delayed action can leave you with USDT still in your wallet while you sort out the fee balance. Check which network your wallet is set to, and look at its ETH balance on that network. An ETH balance on Ethereum is separate from an ETH balance on Manta Pacific.
Use Manta Bridge’s official app as a way to make a transfer between Ethereum and Manta Pacific. The decision rule is simple: keep enough ETH on the network where each planned transaction will happen, and check the wallet’s fee estimate before approving it.