Estimate endpoint

POST /estimate/{sourceFileExtension} estimates one file and one options payload without uploading the file.

Find valid options

Call GET /options/{format} before building an options payload. It returns the valid capability ids, default selections, and allowed option values for that source format.

GET /options/mp4
X-Fast-Api-Key: YOUR_API_KEY

{
  "format": "mp4",
  "job": "extract.mp4",
  "defaults": {
    "selectedCapabilities": ["video.audio", "video.frames", "video.metadata", "video.subtitles"],
    "includeManifest": true,
    "capabilityOptions": {
      "video.audio": {
        "audioFormat": "mp3"
      },
      "video.frames": {
        "frameMode": "every-n-seconds",
        "frameIntervalSeconds": 1,
        "maxExtractedFrames": 500
      }
    }
  },
  "capabilities": [
    {
      "id": "video.audio",
      "output": "audio",
      "defaultSelected": true,
      "options": [
        {
          "id": "audioFormat",
          "type": "enum",
          "defaultValue": "mp3",
          "allowedValues": ["mp3", "wav", "m4a", "original", "best"]
        }
      ]
    },
    {
      "id": "media.transcript",
      "output": "transcript",
      "defaultSelected": false,
      "options": [
        {
          "id": "transcription.mode",
          "type": "enum",
          "required": true,
          "defaultValue": "fast",
          "allowedValues": ["fast", "quality", "meeting-intelligence"]
        }
      ]
    }
  ]
}

Use capabilities[].id in options.extraction.selectedCapabilities. If a selected capability has options[], put each value under options.extraction.capabilityOptions[capability.id][option.id].

Request

POST /estimate/mp4
Content-Type: application/json
X-Fast-Api-Key: YOUR_API_KEY

{
  "fileSizeMb": 25,
  "durationMinutes": 3,
  "options": {
    "extraction": {
      "selectedCapabilities": ["video.audio", "video.metadata", "media.transcript"],
      "capabilityOptions": {
        "media.transcript": {
          "transcription.mode": "quality"
        }
      }
    }
  }
}

Path params

Param	Required	Notes
`sourceFileExtension`	Yes	Source extension with or without the dot, such as `mp4`, `pdf`, `docx`, or `zip`.

Fields

Field	Required	Notes
`fileSizeBytes` or `fileSizeMb`	Yes	Used for file-credit pricing and limits.
`durationSeconds` or `durationMinutes`	Yes for audio and video	Those formats price on duration.
`pageCount`, `slideCount`, `sheetCount`, `documentUnitCount`	Yes for documents	Send the metric that matches the source type: `pageCount` for PDF and Word, `slideCount` for PowerPoint, `sheetCount` for Excel.
`frameCount`	Yes for frame-billed images	Applies to `avif`, `avifs`, `gif`, `ico`, `png`, `tif`, `tiff`, and `webp`, including single-frame files.
`workflow`	No	`extract` by default; use `transcribe` for transcript-only estimates.
`mode`	For transcript-only mode override	`fast`, `quality`, or `meeting-intelligence`.
`options`	No	Same extraction option object accepted by `POST /extract`.

Most formats price on the highest of two or more metrics — for example a PowerPoint deck costs the greater of 1 credit per 5 MB and 1 credit per 5 slides. The endpoint prices only from metrics you send, so it refuses to answer at all when one is missing rather than return the cheaper partial figure. Read the metric from the file before estimating; every value is available locally without uploading anything.

Response

{
  "job": "extract.mp4",
  "category": "video",
  "quotedCredits": 16,
  "lineItems": [
    {
      "kind": "base",
      "credits": 1
    },
    {
      "kind": "capability",
      "capabilityId": "media.transcript",
      "credits": 15,
      "mode": "quality",
      "unit": "minute"
    }
  ]
}

Credit quote

quotedCredits is the quoted credit cost for the file and option payload. lineItems breaks that quote into base extraction and selected priced add-ons.

Errors

Status	Code	Meaning
400	`estimate.unsupported_format`	The source extension is not supported.
400	`estimate.invalid_file_size`	`fileSizeBytes` or `fileSizeMb` is missing, zero, or negative.
400	`estimate.duration_limit_exceeded`	The duration exceeds the limit for your plan.
422	`estimate.exact_metrics_required`	A metric this format prices on was not supplied.

estimate.exact_metrics_required names exactly what to send:

{
  "error": "estimate.exact_metrics_required",
  "format": "pptx",
  "job": "extract.pptx",
  "params": {
    "format": "pptx",
    "job": "extract.pptx",
    "missingMetrics": ["documentUnits"],
    "documentUnitKind": "slides",
    "fields": ["slideCount", "documentUnitCount"]
  }
}

Send any field from params.fields and retry. A 647 KB, 9-slide deck costs 2 credits (ceil(9 / 5) beats ceil(0.647 / 5)), so quoting it on file size alone would show 1 credit and then charge 2. The endpoint returns this error instead of a number it cannot stand behind.

PreviousRate limits

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