Cross chain swaps can involve more than one type of cost, and the final amount isn't always just a simple “swap fee.”
WHAT ARE YOU PAYING FOR?
The total cost can include:
Source chain gas: The blockchain fee required to initiate the transaction.
Execution costs: Fees associated with processing and settling the cross chain swap.
Destination costs: Depending on the route, additional blockchain or execution costs may apply.
Price impact: Your trade can move the price, especially with larger or less liquid swaps.
WHY FEES VARY
Different blockchains have different fee structures and network conditions.
A transaction involving Ethereum can have a very different gas cost from one using Base or Polygon, so the same cross chain swap may have different costs depending on the route.
FEE ≠ PRICE IMPACT
These are different.
Fee is what you pay for transaction or execution services.
Price impact is the difference caused by your trade interacting with available liquidity.
Slippage can also occur when the market moves between the quoted price and execution.
BEFORE YOU CONFIRM
Always review the swap quote first.
Check the amount you're sending, amount you'll receive, estimated fees, route, and any price impact or slippage information before confirming.
MY TAKE
The cheapest looking route isn't always about the lowest fee alone. You also need to consider the final amount you receive after execution costs and price effects.