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

# Metering

> How Compose prices provider output and settles paid inference.

Metering is the part of the request that turns provider output into a bill. Compose does it after execution, using the resolved catalog row and the usage or media evidence returned by the adapter.

For text models, that usually means tokens. For media models, it can mean generated images, audio seconds, video seconds, or provider-specific units from the catalog pricing table.

## Amounts

All settlement amounts are USDC atomic units. USDC has 6 decimals:

```text theme={null}
1 USDC = 1000000
```

The final amount is:

```text theme={null}
provider amount + platform fee
```

The API applies a 1% platform fee on top of the raw amount. Our fees are the lowest in the space, minimum 5.5x times lower than other aggregators (e.g., OpenRouter charges 5.5%).

## Meter subject

Meter subjects use the resolved provider and public model ID:

```text theme={null}
{provider}:{modelId}
```

Examples:

```text theme={null}
azure:gpt-5.5
openai:openai/gpt-5.5
cloudflare:@cf/meta/llama-3.3-70b-instruct-fp8-fast
```

The public model ID stays in the subject so receipts match what the client requested.

## Line items

A metered quote contains one or more line items:

```json theme={null}
{
  "subject": "azure:gpt-5.5",
  "lineItems": [
    {
      "key": "input",
      "unit": "usd_per_1m_input_tokens",
      "quantity": 1000,
      "unitPriceUsd": 1.25,
      "amountWei": "1250"
    }
  ],
  "providerAmountWei": "1250",
  "platformFeeWei": "13",
  "finalAmountWei": "1263"
}
```

Units are normalized before settlement. The metering code supports per-unit pricing, per-1k and per-1m units, and time-based units such as seconds.

## Authorization and settlement

Compose separates authorization from settlement:

| Phase         | What happens                                                                                  |
| ------------- | --------------------------------------------------------------------------------------------- |
| Authorization | The request reserves an exact amount or an `upto` cap.                                        |
| Execution     | The selected adapter runs the provider call.                                                  |
| Settlement    | The API extracts authoritative usage/media evidence, prices it, and settles the final amount. |
| Abort         | If execution fails before settlement, the prepared payment is released.                       |

Audio requests can be quoted exactly up front when request-side billing metrics are known. Usage-priced text, image, and video calls usually use a budget cap and settle after output.

## Quote a model manually

```bash theme={null}
curl https://api.compose.market/api/payments/meter/model \
  -H "Content-Type: application/json" \
  -d '{
    "modelId": "gpt-5.5",
    "provider": "azure",
    "modality": "text",
    "usage": {
      "promptTokens": 1000,
      "completionTokens": 250,
      "totalTokens": 1250
    }
  }'
```

Use this endpoint when you need to inspect how a catalog row prices a known usage record.

## Related

* [x402](/x402/introduction)
* [Facilitator](/x402/facilitator)
* [Model catalog](/inference/reference/specification)