Why a cross-chain swap can deliver less than its quote

A cross-chain swap can deliver fewer tokens than its quote when prices or available liquidity change before both sides of the trade finish. Slippage is the gap between the quoted amount and the amount you receive.

• Price changes while the swap is pending
• Limited liquidity in a pool or route
• Fees and exchange rates on each chain
• The slippage limit set in your wallet

Why does a cross-chain swap have slippage?

A cross-chain swap depends on trades or transfers on more than one network, so its final amount can depend on several prices and pools. A route may exchange your token for an intermediate asset, move value across chains, then exchange that asset for the token you want.

On an automated market maker, a pool’s price shifts as trades change the balance of its tokens. A large trade against a small pool can move the price more than the same trade against a deeper pool. This is called price impact: the effect your own trade has on the pool price.

Slippage can also come from other trades changing the pool before yours is processed. A quote is a snapshot, not a promise. On a cross-chain route, the second step may happen after the first, leaving more time for prices or liquidity to change.

What does a wallet’s slippage tolerance control?

Slippage tolerance sets how far the execution price can move from the quote before the swap is rejected. It is a limit, not a forecast of how much you will lose. If the final amount falls outside that limit, a wallet or route may stop the swap rather than complete it at a worse price.

Some routes show a minimum received amount. This is the least the transaction is set to deliver under its conditions. Check that amount before you approve the swap, and compare it with the quote and any fees the interface lists.

A tighter tolerance can protect you from a larger price change, but it can also cause a swap to fail when the market moves slightly. A wider tolerance makes execution more likely, while allowing a worse result. The useful setting depends on the route and the amount; copying a setting from another swap may not suit yours.

How do bridge delays and fees affect the final amount?

Each cross-chain route handles transfers differently. Some use liquidity on both chains; others rely on a bridge or a service that coordinates separate steps. The route’s timing and exchange rates matter, so check whether the quote is fixed for a period and what happens if one step takes longer than expected.

Fees can reduce what arrives even when the token price barely changes. A route may charge for a swap, a bridge transfer, or the destination-chain transaction. Network fees may be paid in a different token from the one you send, so make sure you have enough for any wallet prompt that asks for one.

If you are checking what happens when a bridge transfer involves an unsupported token, the mantle bridge guide covers the recovery steps in more detail. That issue concerns token support and delivery; it is separate from the price movement usually meant by slippage.

How can you decide whether to proceed or retry?

Start by checking the quoted output, minimum received amount, route, and fees together. A good headline rate can be offset by a costly second swap or by fees on the destination chain. If the wallet does not explain what each amount includes, pause and inspect the route details before approving.

For a large trade relative to the available pool, splitting it into smaller swaps may reduce price impact, though each swap can add fees and expose you to further price changes. Compare the total expected cost rather than assuming smaller transactions are always better. If the quote changes while you review it, request a fresh quote.

When the minimum received amount is too low for you, wait for a better quote or choose a route with a clearer cost. If a swap fails, check whether the wallet reports a fee or a completed first step before trying again; cross-chain routes can have different failure handling. Treat the quote as an estimate, and use the minimum amount to judge the result you are willing to accept.