Separate the cost of sending a bridge transaction from the fee a route quotes for its service: on Ethereum, gas is paid in ETH to execute the transaction, while a service fee is a separate charge shown in the route’s quote. For an ERC-20 deposit, an approval may require its own Ethereum transaction, so the gas cost can include two transactions before the tokens arrive on Manta Pacific.
- Ethereum source gas is calculated from gas used and the transaction’s effective gas price; it is not the bridge service fee.
- Check whether a quoted fee is deducted from the amount sent or charged separately, and compare the quoted receive amount.
- Keep ETH in the source wallet for Ethereum gas, even when bridging a token such as USDC.
What does source gas pay for?
Source gas pays Ethereum validators for executing the transactions you submit on Ethereum Mainnet. The actual charge is gas used multiplied by the effective gas price; with EIP-1559, the wallet’s max fee is a ceiling, not necessarily the amount paid.
For an ERC-20 transfer, the first deposit may need an approve transaction that lets the bridge contract spend the token. The deposit is another transaction, so budget for both; if the token allowance is already sufficient, the approval may be unnecessary. ETH deposits usually avoid the ERC-20 approval step.
For scale, an illustrative 150,000-gas deposit at 21 gwei costs 0.00315 ETH. An illustrative 45,000-gas approval at the same effective price adds 0.000945 ETH. These figures show the calculation, not a live estimate: contract path, calldata, wallet settings, and Ethereum congestion change the gas used or price.
What is a quoted bridge service fee?
A service fee is a charge for providing the route, separate from paying Ethereum to execute your transaction. Depending on the route, it may be a fixed amount or a percentage, or be reflected in the exchange rate or amount received. A route quote can also include network costs, slippage, or a relayer charge, so the word “fee” alone does not identify who receives each part.
Read the quote as a reconciliation: amount sent, any explicitly named service charge, estimated network costs, and expected amount received. Check whether a fee is taken out of the input amount or billed separately. If the route moves the same asset, a material difference between input and expected output needs an explanation in the quote; on a swap route, compare the output after price impact as well.
How should I budget for a Manta bridge deposit?
For a Manta bridge transfer from Ethereum Mainnet to Manta Pacific, treat the source wallet’s ETH balance as the gas budget and the route quote as the estimate of what reaches the destination. If you are sending USDC, the USDC covers the bridged value; ETH covers Ethereum gas. WalletConnect or MetaMask connects the signer, but does not itself pay gas unless the transaction explicitly uses sponsorship or a paymaster.
Suppose you want to move 500 USDC and the quote shows 500 USDC as the input. Check the expected USDC received and any separate fee line, then confirm that the Ethereum wallet has enough ETH for an approval if needed and for the deposit. After arrival, Manta Pacific uses ETH for transaction gas, so reserve some destination ETH if the next action is an app interaction rather than simply holding the tokens.
What can make the final cost differ?
A wallet’s gas estimate is a forecast; the mined transaction’s receipt records the actual gas used and effective gas price. If an approval succeeds but the deposit is delayed or rejected, the approval gas was still spent. A reverted deposit can also consume gas even though the intended transfer did not complete, so check the transaction status before resubmitting.
Before signing, compare the transaction’s network and asset with the quote, and verify whether the displayed fee is gas, a route charge, or both. For an ERC-20, make sure the approval is for the intended token and bridge contract. The decision point is the net amount expected on Manta Pacific against the source ETH you will spend, not a single headline “fee” number.
For a one-off transfer, use the Manta bridge route that matches your asset and destination, then review its quote alongside the wallet’s Ethereum gas estimate. If you are choosing a route for an integration rather than executing this deposit, continue with how to choose a Manta bridge route, which covers that selection in detail.