What a destination gas estimate covers in a cross-chain swap

A destination gas estimate forecasts the cost of completing a cross-chain swap on the receiving chain. It helps a quote account for work that happens after the tokens arrive, such as swapping them or delivering them through a contract. That cost can affect how much the wallet receives, even though the user’s first transaction happens on the source chain.

What does a destination gas estimate include?

It estimates the network fee for the destination-side transaction or transactions in a route. A route that only delivers a token may need less work than one that also swaps it or calls a contract. On an Ethereum-compatible chain, the estimate commonly depends on the amount of computation, called gas, and the network’s current price per unit of gas.

The estimate is separate from the fee for sending the first transaction. That source-side fee is usually paid from the wallet’s balance on the sending chain. Destination costs may instead be covered by a relayer, a service that submits the receiving-chain transaction, and reflected in the quoted fees or output. LI.FI’s quote format lists estimated gas costs and fees separately, while Across describes relayer gas as a cost of filling a transfer on the destination chain. The exact presentation depends on the route.

How does the estimate change the quoted amount?

The route provider estimates the receiving-chain work for the selected path, then uses that estimate when calculating fees and expected output. If the route includes a destination swap, the estimate can differ from a simple token delivery because the swap adds another step. Network conditions matter too: a higher gas price can make the same transaction cost more.

For an example of how a route can connect different networks, see this QuickSwap Ethereum-to-Solana routing guide. Ethereum and Solana do not use the same transaction model, so “gas estimate” is not a universal unit. On Solana, fees relate to a different execution system; compare the quoted cost and what it covers, rather than assuming an Ethereum-style gas figure applies.

What should you check before approving a swap?

Read the quote as a breakdown, not just a headline receive amount. Check whether destination costs are paid separately, deducted from the output, or handled by a relayer. Then compare the minimum output with the estimate. The minimum is the lower bound the route promises under its stated slippage setting; it is not a guarantee that the estimate itself will stay unchanged.

• Confirm the source and destination chains and the token you expect to receive.
• Check which fees are included in the quoted output and which need a separate balance.
• Look for a simulation status or gas limit; skipped simulation can make a gas limit less accurate.
• Refresh an expired or old quote, since gas prices and route conditions can change.

For most users, the practical choice is the route with a clear net receive amount and fee breakdown, not the smallest gas figure on its own. A low destination estimate is useful only if it covers the actual steps needed to deliver the asset. If the quote does not make that clear, compare another route or wait for a fresh quote before signing.