Three Slippage Checks Before a Cross-Chain Swap

A THORChain cross-chain swap can pass through two liquidity pools. That means the price you see depends on liquidity and activity across the route, as well as the time it takes to complete.

Slippage is the difference between the expected price and the price you receive when the swap executes. It is separate from network and protocol fees, though those also reduce your final amount. Before sending funds, make three checks: the minimum output, the route’s liquidity and the timing of the quote.

What does the minimum output tell you?

The minimum output sets the lowest amount you are willing to receive for the input you send. It turns your slippage tolerance into a limit: if the swap cannot meet it, the swap may fail or return funds, depending on the protocol and interface.

Compare the quoted output with that floor before you confirm. A wider gap gives the transaction more room to execute after prices move, but also means you accept a worse result. A narrow gap protects your price more tightly, but a routine change in pool prices or fees could make the swap miss its limit.

Read the amount in the destination asset, not just the displayed rate. Check whether the interface shows fees separately or has already included them in the quote. If a fuller explanation of why one chain’s congestion can affect the timing is useful, this thor swap reference covers that timing question in more detail.

Do not treat a quoted tolerance as a prediction of how much the market will move. It is a boundary you choose, not a guarantee that the trade will execute or that the displayed estimate will hold.

How can you judge the route’s price impact?

Check how much of the available pool liquidity your swap uses. In an automated market maker, a larger trade relative to pool depth shifts the pool’s asset ratio further, which worsens the execution price. A small displayed fee does not necessarily mean the price impact is small.

On a two-pool route, each leg can contribute to the final result. A deep first pool cannot make up for a shallow second one; the output asset may be most exposed to price impact on the thinner leg. If the interface shows the route or per-leg estimates, look at both rather than judging only by the headline exchange rate.

Use the preview to compare the expected output with the amount you would consider acceptable. The useful questions are:

• Does the interface show the source and destination assets and the route between them?
• Is the estimated output close to your minimum, leaving little room for a price change?
• Are fees and price impact shown in a way you can distinguish?

For a large swap, the choice is often between speed and price. THORChain’s streaming swaps divide execution into smaller parts over time, which can reduce the impact of a single large trade on pool prices. The trade-off is that completion takes longer, so later parts still face changing conditions.

When should you check the quote again?

Recheck the quote if there is a meaningful delay before you send the source-chain transaction. A quote reflects conditions at a moment; while the transaction waits for confirmation, pool balances can change, and congestion can delay one leg of a cross-chain route.

Congestion does not automatically mean the swap has a worse exchange rate. It can, however, stretch the time between quoting, depositing and receiving the destination asset. During that interval, the pool price may move, and the transaction may no longer fit the minimum output you chose.

Before you confirm, use this sequence:

1. Review the input, destination asset, route, fees and estimated output.
2. Set a minimum output you can accept, based on the quote and the trade’s purpose.
3. If the quote has gone stale or conditions have changed, refresh it and review the new terms before sending.

After sending, use the transaction details provided by your wallet or swap interface to follow its progress. Avoid submitting a second swap just because the first takes longer than expected; first check whether it is pending, completed or refundable.

The practical rule is to use the minimum output to define your price boundary, pool depth to judge likely price impact, and a fresh quote to account for timing. Together, those checks help you decide whether the expected destination amount is worth accepting before you commit funds.