Acrossbridge quotes distinguish transfer fees from destination amounts

Expected output and minimum output

The expected output estimates the destination tokens that a route will deliver, while the minimum output states the quoted lower bound. The fields expectedOutputAmount and minOutputAmount therefore have different jobs: one helps compare expected outcomes, and the other specifies an execution requirement. When those figures differ, the gap allows for execution variation. It does not establish that the protocol charges the entire difference. The bound applies within the quote's trade type, slippage settings, and execution conditions; it does not promise that every deposited intent will fill.

A route that cannot meet an enforced output requirement may fail before delivering tokens.

The amount field follows the trade type

With exactInput , amount refers to the input token: the request fixes the quantity to spend. The API calculates destination output after fees. For minOutput and exactOutput , amount instead refers to the output token, and the API calculates the required input.

minOutput targets at least the specified output and allows a larger delivered amount. exactOutput targets a precise amount, subject to the route satisfying that trade type. Enforcing strictTradeType=true prevents a fallback when the requested type cannot be met. In the response, inputAmount gives the quoted input and maxInputAmount gives its maximum. These are spending amounts, not separate charges to add together.

Token decimals set the scale

The API expresses token quantities in the smallest unit for the relevant token. USDC uses six decimal places, so 1,000,000 units represent 1 USDC. Token decimals translate API quantities into readable amounts; they do not create an extra charge. Different tokens can use different scales, and matching decimal counts do not imply equal token values. Each amount needs its token identity, chain, and decimals for an accurate conversion.

Origin gas has its own cost line

Origin gas pays for the transaction submitted on the starting chain. The Swap API response reports origin-chain gas separately under fees.originGas . Its token metadata identifies the gas asset, so its raw amount may use a different denomination from the transfer fee.

The relayer's charge already includes compensation for submitting the destination-chain fill transaction. Adding that destination gas component again to the full bridge fee would count the same quoted cost twice. Conversely, omitting origin gas would understate the wallet's spending. A cost comparison in one currency needs consistent value conversions, rather than a sum of unrelated token quantities. The quote's gas estimate also remains an estimate until execution.

Bridge fees compensate different participants

The bridge fee combines a liquidity provider, or LP, component with the relayer's charge for filling the intent. LPs supply capital and bear utilization and rebalancing costs. Relayers advance destination funds, pay fill gas, and face capital costs while awaiting repayment.

A single fee percentage can therefore cover several cost drivers. Destination gas varies by network. Relayer pricing also reflects capital tied up before settlement and risks such as chain reorganizations or settlement delays. The breakdown identifies these components without assigning permanent proportions to them. Fast delivery to the recipient and later relayer repayment concern different time intervals; a fast fill does not eliminate the capital cost built into the quote.

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LP pricing and the repayment-chain condition

LP pricing responds to pool utilization and the selected token and route. The utilization curve raises rates as available liquidity becomes more heavily used, with a steeper slope beyond a configured threshold. A reusable flat percentage can therefore misdescribe a later quote.

An annualized rate differs from a transfer charge. The model converts that rate to a weekly rate using (1 + R_annual)^(1/52) - 1 and applies the weekly rate to the transaction size. The week is the fee's rate-conversion period, separate from the fill time.

The LP fee is zero when the relayer takes repayment on the deposit's origin chain. Repayment on another chain brings rebalancing into the LP calculation. The relevant condition concerns the relayer's repayment chain, not simply the destination selected by the user. Relayer charges and separately quoted origin gas can remain.

Swap impact and maximum quoted costs

Swap impact describes value changes introduced by trading within a route. It differs from the charge for bridging the intermediate asset. The response can include origin-swap and bridge details, with token metadata attached to each amount.

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The total breakdown can report swapImpact beside bridge and app costs. A negative entry reduces the displayed total relative to its other components. The response also distinguishes fees.total from fees.totalMax , including a maximum-swap-impact breakdown. These represent estimated and maximum costs under the quote's execution constraints, not two bills to add together. Origin gas retains its separate line.

An origin swap can change the asset before the bridge step. The bridge component then describes the intermediate asset, while any app charge uses the destination token. Each fee amount's attached token metadata identifies its denomination. When the response supplies amountUsd , that field gives the quoted dollar valuation; it does not turn the original amount into a dollar quantity.

App fees in the destination token

An integration can add an optional appFee beyond the LP and relayer charges. It collects that fee in the output token on the destination chain through appFeeRecipient . The parameter uses a decimal fraction: 0.01 means 1%. A positive fee requires a recipient address valid for that destination. EVM destinations use an EVM address; Solana destinations use a base58 public key. This integration charge can coexist with a zero LP fee.

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Slippage across the route's swap legs

Numeric slippage sets an allowance for execution variation, and the API expects a decimal fraction. A setting of 0.005 represents 0.5%. The automatic option lets the API select that allowance. A tolerance setting belongs to the quote's execution constraints, separate from the protocol's fee components.

For a route with swaps on both origin and destination, a numeric tolerance splits equally across those legs. The request's value is therefore not a full allowance duplicated at each end. The expected output, minimum output, and enforced trade type must be read together. Increasing tolerance changes the accepted execution range; it does not establish that the expected amount will arrive or that the entire allowance will become a fee.

Quote expiry and fill deadlines

Quote expiry ends the validity of pricing data, while the fill deadline limits when a relayer can complete a deposited intent. The response's quoteExpiryTimestamp and the intent's fillDeadline serve those separate purposes. Fees change with gas prices, market conditions, and utilization, so execution needs fresh pricing.

The quote also includes expectedFillTime , an estimate in seconds. If an unfilled deposit expires and qualifies for a refund, settlement must process it before funds return. Refund processing can take several hours after expiry, including bundle processing, the challenge period, and bridge delays. That period differs from the quoted fill estimate.

Fresh fixed-input quotes compare destination amounts for the same token input. Output-targeted quotes compare the input needed to meet a shared destination requirement, with each quote's origin gas counted separately.