Compare the value you actually receive, then subtract any costs paid separately. A quoted rate can hide the difference between the market price and your execution price, while network fees may be charged outside the swap. To compare routes fairly, value each one in the same currency against the same reference price.
What counts as the full cost of a cross-chain swap?
The full cost is the value you send minus the value you receive, plus any extra fees you pay separately. This includes the trading price, network fees, and any fee charged by the swap service.
The trading price can differ from the market reference price because of a spread or price impact. A spread is the gap between a buyer’s and seller’s prices. Price impact means a large trade moves the price as it uses available offers. Ethereum.org explains that Ethereum gas fees vary with network demand; Solana’s official fee documentation describes a base fee and an optional priority fee. So the network part of your cost depends on where the transaction happens and when.
Use the amount that will reach your destination, not a headline rate. If a fee is already reflected in that amount, do not subtract it twice. Add a fee separately only when you will pay it outside the quoted swap amount.
How do you compare two routes with a real example?
Imagine sending $1,000 worth of USDC to receive bitcoin, with bitcoin’s reference price at an illustrative $100,000. A perfect market-price exchange would produce 0.010 BTC before costs. Now suppose Route A estimates 0.00982 BTC at the destination and charges $3 in separate source-network fees.
At the example reference price, Route A delivers $982 in bitcoin. Your total cost is $21: the $18 gap from the reference value, plus the $3 separate fee. If Route B estimates 0.00978 BTC and charges $1 separately, it delivers $978 and costs $23. Route A is cheaper, even though its separate fee is higher.
Use the same input amount, destination asset, reference price, and timing for each comparison. The Chainflip example fits this method: its just-in-time automated market maker, a trading system where liquidity providers update prices around each swap, can affect the final trading price. Compare the expected destination amount and separately paid costs together, rather than judging by a fee label alone.
Why might the final amount change?
An estimate can change because the market moves before the swap executes or because available offers change. In Chainflip’s documented process, a deposit is first confirmed on its source chain; then the State Chain, Chainflip’s own accounting blockchain, processes the swap. That delay means the estimate is not a guarantee of the final amount.
Before choosing, check when the estimate expires and whether a lower-than-expected output would change your decision. Confirm the destination asset and address, then compare the final amount you expect to receive with any fees paid separately. If timing or price movement matters, repeat the comparison close to when you intend to act.
For a fair cost comparison, value the destination amount at one shared reference price, then add only fees paid outside that amount. This shows which route leaves you with more of the asset you wanted.