How to Set a Safe Minimum Output for a Cross-Chain Swap
A minimum output is the least amount of the destination asset you are willing to receive for a swap. The key is setting it low enough to allow for normal price movement, but high enough that you would rather have the swap fail than accept less.
What does a minimum output protect?
It sets a floor for the swap’s execution: if the available price falls below that floor, the swap should not complete under the protection rules you chose. The comparison may happen at the trading step, before all network costs are taken out, so a minimum output does not always mean that exact amount will land in your wallet.
For the full walkthrough of swapping between networks, read how Chainflip swaps BTC for ETH. This guide focuses on the separate decision you face before sending: how much output is too little to accept.
A quote is an estimate based on conditions at a particular moment. In a cross-chain swap, the deposit must first be confirmed on its source chain, so the market can move before the trade executes. With Chainflip, Validators witness the incoming transfer, then the trade is processed in its JIT AMM, where liquidity providers compete to fill it. That process can improve the execution price, but it does not make an earlier quote a guaranteed result.
How do you choose a floor that fits your trade?
Start with the quoted output, then choose how much movement you are willing to tolerate. Express that tolerance as a percentage and multiply the quote by one minus that percentage.
Write down the quoted output. Suppose you plan to swap 0.10 ETH and the estimate is 15 SOL. Treat 15 SOL as a reference for your calculation, not a promise of what will arrive.
Choose your tolerance. If you choose 1%, you are saying that you will accept up to a 1% drop at the protected trading step. A smaller tolerance means a stricter floor and a greater chance the swap will be delayed or refunded if the market moves.
Calculate the minimum. Multiply 15 SOL by 0.99 to get 14.85 SOL. That example floor means the trade can proceed at 14.85 SOL or better under the relevant price check; if its result is lower, the protection should prevent it from executing at that price.
Check whether the amount is net or before costs. A cross-chain transfer can involve a fee on the source-chain deposit, trading fees, and a fee for broadcasting the destination transfer. Some costs are accounted for outside the AMM price check. A 14.85 SOL floor at the trading step may therefore result in less than 14.85 SOL arriving. Read how the estimate defines its output before treating your calculated floor as a wallet balance.
Which price protection should you use?
Use a minimum output when you care about the least amount you will accept in the destination asset. It is direct: you set a floor for the trade’s result. Some swap routes also offer protection against movement from an external reference price, often called oracle or live-price slippage. That compares the execution with an indexed market price rather than only with your quoted output.
Those checks answer different questions. A minimum output asks, “Will I receive at least this amount from the swap?” A live-price check asks, “Is the swap price still close enough to the broader market?” Where both are available, use the check that matches your concern and make sure the asset pair supports it. The external price check may not include protocol or broker charges either.
For Chainflip, the AMM can execute a trade after Validators confirm the deposit, and its JIT AMM gives liquidity providers a short window to compete on price. This is why the estimate can change between deposit and execution. A tighter minimum can stop an unattractive result, but it may also cause the swap to wait for another attempt and then return funds if the limit is still unmet before its retry period ends.
What should you check before sending?
Use this final pass to make sure the floor protects the outcome you actually care about:
Check the destination asset and address. The floor is only useful if the swap is set to deliver the asset you intend to receive to the address you control on the correct network.
Compare the quote with your calculated floor. If the quote itself is close to the least amount you would accept, consider waiting or changing the amount. Do not raise the floor just to make the swap more likely to proceed.
Allow for execution time. Source-chain confirmations and price movement can make a quote stale. Recheck the estimate before committing, especially if the market is moving quickly or the route uses multiple trading pools.
Know what a failed check means. Depending on the protocol and route, the swap may retry and then refund to a specified source-chain address if the price stays outside your limit. A refund can still involve transaction costs, so use an address you can access and understand that a refund is not the same as an instant cancellation.
Set the floor from the least net outcome you can accept, and leave room for the fees and timing that sit outside the price check.