Acrossbridge fees span two gas markets and one relay quote

Acrossbridge fees split a cross-chain transfer across two gas markets: you pay to submit the deposit on the source chain, while the relay quote includes the cost of filling it on the destination. The distinction matters because the two costs are paid differently and can move for different reasons. Across’s fee materials at acrossbridge.dev describe the quote as a combination of liquidity and relayer costs. A transfer’s displayed fee is therefore not a single gas charge.

What does the source-chain gas fee pay for?

The source-chain gas fee pays for the transaction that records your deposit. Your wallet sends that transaction to a pool contract on the chain where your funds begin. The network charges gas in its own terms, and your wallet must have enough of the chain’s native token to submit it.

This charge sits outside the bridge’s quoted relay fee. A wallet may show the network fee separately from the amount that will arrive on the destination chain. If the source network is busy, this cost can rise even if the route’s relay quote has not changed. Conversely, a quiet source chain does not guarantee a cheap transfer if destination execution or liquidity costs are high.

How does acrossbridge price destination gas?

Acrossbridge prices destination execution through the relayer fee included in the quote. After the deposit is observed, a relayer uses its own funds to send the promised tokens to the recipient on the destination chain. It pays that chain’s gas to submit the fill transaction, so the user does not ordinarily need to spend destination-chain native tokens just to receive the bridged funds.

The relayer’s gas bill is only one piece of this fee. The quote can also account for the capital tied up while the relayer waits for settlement, along with the liquidity provider’s fee for capital use and rebalancing. The destination gas component varies with the chain and the transaction needed to fill the transfer. The liquidity component varies by route and pool conditions. In the protocol’s fee accounting, the total fee is the difference between the deposited amount and the quoted output amount.

Think of it like ordering something to a second city: the sender pays to place the order, while the courier advances the delivery cost and later settles the bill. The analogy stops there: a bridge fill is an on-chain transaction, and its price depends on the route’s live conditions.

How can you read a bridge quote?

Read the quote as a destination amount plus a breakdown, then check the source wallet’s network fee separately. A suggested-fees response can report relay costs, including relayer gas and capital fees, as well as route limits and an estimated fill time. These fields help explain why two routes for the same asset can have different costs.

• Check the source gas estimate in your wallet before signing the deposit.
• Compare the input amount with the quoted output, not just a fee percentage.
• Look at the relay fee breakdown and route limits for the exact chains, tokens and amount.
• Refresh the quote immediately before sending; gas prices and pool utilization change.

For most users, the best comparison is the amount that will arrive after all quoted bridge costs, with source gas added separately. A route that looks cheaper by its relay percentage may still cost more once the source transaction is included. And receiving funds without paying destination gas for the fill does not cover later actions: a swap or contract call after arrival may require that chain’s native token.

What changes from one quote to the next is the balance between two networks’ gas conditions and the route’s liquidity and capital costs. Watch the final output and refresh the full quote before depositing; neither chain’s gas market stands in for the other.