For a cross-chain swap, set slippage tolerance just above the expected price movement during execution: a quiet, liquid route may need around 0.1–0.5%, while a volatile or thinly traded asset can need more. The right figure depends on the route’s liquidity and how long execution takes; a larger tolerance can let you receive less than the quote.
Slippage tolerance sets a limit on execution price
Slippage is the difference between the price shown when you request a swap and the price at which it executes. Tolerance is the maximum difference you agree to accept before a swap leg reverts; it does not improve the quoted price or guarantee a particular final value on the destination chain.
For example, if a destination swap quotes 100 tokens and you set 0.5% tolerance, that leg may accept as few as 99.5 tokens. If the market moves further before execution, the leg can fail instead. The Ethereum Foundation’s documentation on transactions is useful context here: execution happens on-chain, so the state available when a transaction is processed can differ from what you saw when it was prepared.
A cross-chain swap may involve a source-chain swap, a transfer between networks, and a destination-chain swap. Each part has its own timing and failure conditions. A tolerance displayed for one swap leg should not be read as a cap on every cost or price change across the whole journey.
Choose tolerance from the asset and route conditions
Start with the quoted output and the assets being exchanged. A liquid pair with steady trading usually needs less tolerance than a small token with shallow liquidity, where even a modest trade can move the pool price. For a volatile asset, prices can also change while the cross-chain transfer is underway.
As a working approach, compare the quote with the minimum output at several tolerance levels. Say a route quotes 100 destination tokens: at 0.5%, the minimum is 99.5; at 1%, it is 99. A wider setting may help a trade execute during fast price changes, but it also permits a worse price. If the minimum output looks unacceptable, reconsider the trade size or route instead of raising tolerance automatically.
When comparing routes, check where each one performs its swaps and which leg has the thinner market. how Biswap chooses a cross-chain route is a concrete example of the route question: the networks and assets involved shape the path, while liquidity and execution conditions affect the amount you may receive. Biswap is a cross-chain bridge and swap service for moving and exchanging assets across networks in one flow.
Know what a failed leg means before trading
A swap leg that cannot meet its minimum output may revert, but that does not mean every earlier step in a cross-chain flow is automatically undone. The bridge transfer and destination swap can be separate on-chain actions, with different confirmation times and recovery behavior. Before trading, check what the service says happens if a later leg fails, and keep the transaction references so you can follow each stage.
Also separate slippage from other deductions. Network gas, bridge costs, and token transfer taxes can reduce the amount that arrives, but they are not necessarily covered by a swap’s tolerance setting. Compare the expected final amount after the route’s stated costs, rather than judging safety from the tolerance number alone.
For a small first trade, choose a tolerance that gives only a modest cushion over the route’s expected movement, then check the minimum output before submitting. If execution fails, review the price and route conditions before trying again; increasing tolerance without understanding the failed leg can expose you to a worse fill.