> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rialto.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Quoting (getAmountOut)

> Implement the read-only quote function Rialto samples at request time.

## Parameters

| Param      | Type    | Meaning                                                                     |
| ---------- | ------- | --------------------------------------------------------------------------- |
| zeroForOne | bool    | true = sell token0, buy token1; false = the reverse.                        |
| amountIn   | uint256 | Exact input amount, in the input token's smallest units.                    |
| returns    | uint256 | Output amount you would deliver now, in smallest units of the output token. |

## Requirements

* View and read-only. getAmountOut must not write state.
* Exact-in only. There is no exact-out path today.
* Unsupported sizes. For an amountIn or pair you cannot fill, return 0 or revert.
  Do not return a price you will not honor.
* Self-consistent with settlement. The price getAmountOut returns is what Rialto
  routes on. Occasional slips from volatility between quote and settle are
  expected, but quotes and swaps should generally agree. Quote your currently
  executable price; if it is oracle-driven, quote from the same oracle you settle
  against.
* Gas. Rialto assigns your leg a gas estimate when ranking routes net of gas,
  calibrated from observed usage at roughly p90 plus 10% headroom. Give a realistic
  gas figure for your swapExactIn; an unrealistically cheap estimate makes your
  route look better than it settles.