Keep enough of the destination chain’s own coin to pay for what you plan to do after the swap. A token balance alone may not cover a later send or trade, even if the swap itself completed.
What coin pays for the next transaction?
Each blockchain has a native coin used to pay its network fees, often called gas. For example, Ethereum transactions use ETH, Solana uses SOL, and BNB Chain uses BNB. A token that represents dollars or another coin usually cannot pay this fee.
The fee depends on the network and the action. Ethereum.org explains that Ethereum gas is paid in ETH; Solana’s documentation says each transaction requires a fee in SOL. A simple send may cost less than a swap, and busy networks can raise the cost.
So, before bridging, name the action you want to take next: hold, send, or trade. If you only want to hold, you may not need to spend destination gas right away. If you want to move or trade the new asset, leave the network coin available for that step.
How much should you leave?
Use the estimated fee for the next action as your starting point, then leave a cushion for a second attempt or another transaction. The estimate is a planning figure, not a promise: fees change with network demand, and some actions use more than one transaction.
For example, say your wallet estimates a swap on Ethereum will cost 0.001 ETH. If you want room to retry or send the resulting token afterward, keeping around 0.003 ETH gives you roughly three times that estimate. Those numbers are illustrative; check the estimate shown for your actual action and destination network.
For a Manta bridge transfer that also swaps assets, the destination token and the fee coin can be different. Manta bridge swaps describes the service’s cross-chain flow; the practical check is still whether you will have the destination network’s coin for your next transaction. Don’t assume that receiving a token also means you received spendable gas.
Leave a little more when the next step is uncertain. For instance, a swap can fail because its price moved, and trying again may require another fee. I would keep enough for two likely actions, rather than sending every last unit into the first swap.
What can leave you short of gas?
The common trap is confusing the coin being moved with the coin that pays fees. A Bitcoin balance cannot pay an Ethereum fee, and a token on Solana cannot pay a Solana fee unless it is SOL. Also check that the destination is the network you intend to use; similar-looking tokens can exist on different chains.
Before confirming, check these three details:
- The destination network matches where you plan to use the asset.
- You know which native coin pays fees on that network.
- Your expected next action has a fee estimate, with some room left over.
Bitcoin fees work differently from Ethereum gas: Bitcoin.org explains that fees depend on transaction data size and demand for block space, rather than simply the amount sent. So a Bitcoin transfer does not create an ETH, SOL, or BNB gas balance on another chain.
For a Manta bridge swap, I would decide my next action first, check that chain’s fee estimate, and keep a cushion in its native coin. That small check makes the arriving asset useful instead of leaving it stuck until you fund gas.