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

# Amounts

Every amount in the Orchestra API is an integer string in the asset's smallest units. `"50000000"` is \$50.00 of 6-decimal USDC. `"100000"` is 0.001 BTC in sats. There are no floats and no decimal points anywhere in the API.

Decimals per asset come from the `source` and `destination` detail objects on `GET /v1/orchestration/routes`. Read them from there; never hardcode decimals in your integration.

## amountMode

One field, `amount`, interpreted by `amountMode`. The mode answers which side of the swap the user is fixing.

**`exact_in`** (the default): the user knows their budget. `amount` is what the user sends; `estimatedOut` is what arrives after fees and execution. Use this for "swap \$50 of USDC" flows.

**`exact_out`**: the recipient must receive an exact amount. `amount` is what the recipient gets, and the API computes `requiredAmountIn` (what the user must deposit) and `maxAcceptedAmountIn` (the ceiling above which the deposit refunds). Use this for payment intents: "the merchant needs exactly 100 USDC."

Exact-out constraints:

* It is per-route. Check `exactOutEligible` on `GET /v1/orchestration/routes` before offering it.
* Stablecoin exact-out amounts must be whole-cent values: multiples of `10000` for 6-decimal stables. A non-cent value returns `400 invalid_request`.
* `refundAddress` is required for `exact_out`, and for any Lightning destination in either mode.

## amountFiatUsd

`amountFiatUsd` pins the sender's USD figure instead of a crypto amount. It is available on `/onramp` and pay links only, and is mutually exclusive with `amount`.

The server converts USD to sats at request time using a Coinbase and Kraken spot oracle. When the spot price is stale, the request fails closed with `503 spot_unavailable` rather than pinning a wrong dollar figure. The accepted range is $1.00 to $50,000.00.

`amountFiatUsd` runs as `exact_in`. Combining it with `amountMode: "exact_out"` is gated to USD-stablecoin destinations and invoice-billing partners, and rejects app and affiliate fees. See [USD-pinned mode](/products/orchestration/onramp#usd-pinned-mode-amountfiatusd) for the full contract.

## Limits

`GET /v1/orchestration/limits` is the authoritative per-route min/max source. The bounds are operator-tuned and change without notice, so query the endpoint instead of hardcoding numbers.

A few constraints are static and enforced in code: BTC swap inputs need at least 5,000 sats from Bitcoin L1 and 1,200 sats from Spark, and Bitcoin L1 delivery needs at least 10,000 sats after route fees. `/limits` reports these alongside the runtime bounds, typed per constraint.

## When the deposit differs from the quote

Deposits do not need to match the quoted amount exactly, and the rules differ by `amountMode`. [Order Lifecycle](/products/orchestration/order-lifecycle#what-happens-if-the-deposit-amount-differs-from-the-quote) owns the full behavior: underpayment, overpayment, and the exact-out refund conditions.

## Where to go next

* [Pricing](/products/orchestration/concepts/pricing) for estimates, quotes, and fixed delivery
* [Fees](/products/orchestration/concepts/fees) for what gets deducted before delivery
* [Quotes and Orders](/products/orchestration/api/quotes-and-orders) for request and response shapes