Price Impact and Slippage on Cross-Chain Swaps

Uniswap Labs defines price impact as the price change caused by a trade; slippage is the difference between a quoted output and what execution returns. On a cross-chain swap, these measures describe different risks: the trade can move a pool’s price, while conditions can change before one or more route steps complete.

What is price impact on a cross-chain swap?

Price impact estimates how much the trade itself changes the price in the liquidity pool or pools it uses. Uniswap Labs says impact depends on trade size and pool liquidity: a larger order relative to available liquidity generally gets a worse average rate. That cost is part of the quote, even if the market does not move before execution.

A cross-chain route may combine a swap on the source chain, a transfer between chains and a swap on the destination chain. Across’s Swap API documentation describes routes with different combinations of those steps, so the displayed output can reflect multiple swaps, transfer fees and exchange rates. For a walkthrough of the interface, see these QuickSwap cross-chain swap steps.

What does slippage mean when swapping across chains?

Slippage is the difference between the amount shown in a quote and the amount received when the transaction executes. Uniswap Labs describes a swap’s maximum slippage as a setting that determines its minimum output. If the final output falls below that limit, the swap may fail instead of completing at a worse rate.

Across’s Swap API documentation says a numeric slippage setting can be divided between the origin and destination legs of a route. That makes the setting a limit on execution, not a prediction that the full allowance will be used. A tighter limit reduces how much worse the output can be, but raises the chance that the transaction will not execute if prices shift.

How should you compare the quote and slippage setting?

Check the estimated output, minimum output, fees and route before signing. Uniswap Labs lists price impact, fees, network cost and maximum slippage as separate swap details; Across also notes that cross-chain output varies with fees, slippage and exchange rates.

• Price impact: the estimated price effect of the trade size on pool liquidity.
• Slippage: the permitted difference between quoted and executed output.
• Fees: costs charged by the route that reduce what reaches the destination.
• Minimum output: the least amount accepted under the selected slippage limit.

A high price impact calls for reviewing the trade size or route; a wide slippage limit allows a larger execution shortfall. Compare both figures with the minimum output before signing. The final received amount remains unknown until the route executes, and the exact outcome depends on the pools, fees and route used.