Keep around 0.1 POL on Polygon for a later transaction; it is a practical buffer, not a fee quote. Polygon PoS charges transaction fees in POL, while BNB pays fees on BNB Chain. The balance you need depends on what you do next and current network traffic.
A cross-chain swap moves value from one network to another and exchanges it along the way. A separate POL top-up means another transfer; the quickswap swap service can move and swap assets across chains in one flow. Either way, check that your wallet receives value on Polygon PoS before relying on it for gas.
Choose one flow when you can receive POL
A single cross-chain flow is convenient when you want to arrive with both your main asset and some POL. It saves you from arranging a separate top-up, but only works if the route can deliver POL to Polygon PoS. Check the destination network and final asset before you confirm.
For example, say you start with $100 worth of an asset on BNB Chain and want $95 worth of a stablecoin on Polygon, leaving about $5 of value for POL. Those figures are illustrative: the actual amounts depend on prices, network fees, and the available route. The important check is that the result includes POL on Polygon PoS, rather than POL or another token on BNB Chain.
The mechanism has two parts: the source asset is sent from BNB Chain, then the destination side settles the assets on Polygon. A stablecoin arriving on Polygon cannot pay the network fee by itself. Polygon’s POL guidance identifies POL as the gas token for Polygon PoS, so keep some available even if most of your balance is in another token.
I’d pick this approach when the route clearly leaves a useful POL balance and you want fewer separate transactions. It may not fit if the route cannot deliver POL, or if you need to control the exact amount you keep for fees.
Top up on Polygon when you need control
A separate top-up is the clearer option when you already have assets on Polygon but no POL, or when you want to choose the gas reserve yourself. You need POL to arrive on Polygon PoS: sending it to the same wallet address on BNB Chain does not help pay a Polygon fee.
Suppose your next action is a token transfer followed by a swap. Around 0.1 POL is a reasonable illustrative reserve for a few routine actions, but the wallet’s current fee estimate is the better guide. PolygonScan’s gas tracker distinguishes actions such as transfers and swaps; a swap can use more gas than a simple transfer because it calls a trading contract.
If the wallet shows too little POL, arrange a small deposit on Polygon PoS before starting the next action. You can buy or transfer POL from a source that supports that network, but check the selected network carefully. A token with the same name on another chain is not a substitute for POL on Polygon PoS.
This option adds a transaction and may add a separate transfer cost, but it gives you a direct way to set aside gas. If a swap arrives without POL, the assets are not necessarily lost; you may simply need a small POL deposit before you can move them.
For a quickswap cross-chain swap, think about the next Polygon action before choosing what you want to receive: keep a small POL reserve there, or plan a separate top-up.