Video inference API

Generate videos from text prompts, use images to guide video generation, or transform existing videos with Runware's video inference API. Complete reference for all video generation parameters.

Introduction

Video inference enables video generation and transformation. This page is the complete API reference for video inference tasks. All workflows and operations use the single videoInference task type, differentiated through parameter combinations.

Core operations

Text-to-video: Generate videos from text descriptions.
Image-to-video: Generate videos using images to guide content or constrain specific frames.
Video-to-video: Transform existing videos based on prompts.

Advanced Features

Style and control: Camera movements with cinematic lens effects, keyframe positioning.
Content generation: Video extension capabilities, multi-shot storytelling with scene transitions.
Visual effects: Effect templates and stylized filters.
Identity and character: Character lip-sync, reference-based generation.
Audio: Native audio generation with synchronized dialogue and effects.

Each feature includes detailed parameter documentation below.

Video generation uses asynchronous processing due to longer processing times. Setting "deliveryMethod": "async" queues your task and returns an immediate acknowledgment. Use the getResponse task to poll for status updates and retrieve the final video when processing completes.

Request

Our API always accepts an array of objects as input, where each object represents a specific task to be performed. The structure varies depending on the workflow and features used.

The following examples demonstrate how different parameter combinations create specific workflows.

Text to Video

{
    "taskType": "videoInference",
    "taskUUID": "24cd5dff-cb81-4db5-8506-b72a9425f9d1",
    "positivePrompt": "A cat playing with a ball of yarn, high quality, detailed",
    "model": "klingai:5@3",
    "duration": 10,
    "width": 1920,
    "height": 1080,
    "seed": 42,
    "numberResults": 1
  }

Image to Video

{
    "taskType": "videoInference",
    "taskUUID": "b8c4d952-7f27-4a6e-bc9a-83f01d1c6d59",
    "positivePrompt": "smooth animation, natural movement, cinematic quality",
    "model": "klingai:3@2",
    "duration": 10,
    "width": 1920,
    "height": 1080,
    "frameImages": [ 
      { 
        "inputImage": "c64351d5-4c59-42f7-95e1-eace013eddab",
        "frame": "first"
      },
      { 
        "inputImage": "d7e8f9a0-2b5c-4e7f-a1d3-9c8b7a6e5d4f",
        "frame": "last"
      } 
    ],
    "numberResults": 1
  }

taskType string required: The type of task to be performed. For this task, the value should be videoInference.

taskUUID string required UUID v4

When a task is sent to the API you must include a random UUID v4 string using the taskUUID parameter. This string is used to match the async responses to their corresponding tasks.

If you send multiple tasks at the same time, the taskUUID will help you match the responses to the correct tasks.

The taskUUID must be unique for each task you send to the API.

outputType "URL" Default: URL

Specifies the output type in which the video is returned. Currently, only URL delivery is supported for video outputs.

URL: The video is returned as a URL string using the videoURL parameter in the response object.

outputFormat "MP4" | "WEBM" Default: MP4

Specifies the format of the output video. Supported formats are: MP4 and WEBM.

MP4: MPEG-4 video format, widely compatible and recommended for most use cases.
WEBM: WebM video format, optimized for web delivery and smaller file sizes.

outputQuality integer Min: 20 Max: 99 Default: 95: Sets the compression quality of the output video. Higher values preserve more quality but increase file size, lower values reduce file size but decrease quality.

deliveryMethod "async" required

Determines how the video generation results are delivered. Currently, video inference only supports asynchronous processing due to the computational intensity of video generation.

When set to "async", the task is queued for background processing and you receive an immediate acknowledgment. Use the getResponse task to poll for status updates and retrieve the final video when processing completes.

Asynchronous delivery is essential for video generation as processing times can range from several seconds to minutes depending on the complexity and length of the requested video.

uploadEndpoint string

Specifies a URL where the generated content will be automatically uploaded using the HTTP PUT method. The raw binary data of the image or video file is sent directly as the request body (not as JSON), enabling webhook-like functionality for immediate processing once generation is complete.

Common use cases:

Cloud storage: Upload directly to S3 buckets, Google Cloud Storage, or Azure Blob Storage.
Webhook services: Send content to your API endpoints or serverless functions for processing.
CDN integration: Upload to content delivery networks for immediate distribution.

URL customization:

You can include query parameters in the URL to help identify and process the uploaded content:

// Using our task UUIDs
https://your-api.com/webhook/media?taskUUID=991e641a-d2a8-4aa3-9883-9d6fe230fff8

// Using your own IDs
https://api.example.com/receive-content?id=img_abc123&projectId=proj_789

// Direct cloud storage upload
https://your-bucket.s3.amazonaws.com/generated/content.mp4

// Multiple parameters for tracking
https://api.example.com/process-media?userId=12345&timestamp=1640995200

The content data will be sent as the request body, allowing your endpoint to receive and process the generated image or video immediately upon completion.

includeCost boolean Default: false: If set to true, the cost to perform the task will be included in the response object.

positivePrompt string required Min: 2

The text description that guides the video generation process. This prompt defines what you want to see in the video, including subject matter, visual style, actions, and atmosphere.

The model processes this text to understand the desired content and creates a video that matches your description. More detailed and specific prompts typically produce better results.

For optimal results, describe the motion, scene composition, and visual characteristics you want to see in the generated video.

negativePrompt string

Specifies what you want to avoid in the generated video. This parameter helps steer the generation away from undesired visual elements, styles, or characteristics.

Common negative prompts for video include terms like "blurry", "low quality", "distorted", "static", "flickering", or specific content you want to exclude.

frameImages object[]

An array of objects that define key frames to guide video generation. Each object specifies an input image and optionally its position within the video timeline.

The frameImages parameter allows you to constrain specific frames within the video sequence, ensuring that particular visual content appears at designated points. This is different from referenceImages, which provide overall visual guidance without constraining specific timeline positions.

When the frame parameter is omitted from frameImages objects, automatic distribution rules apply:

1 image: Used as the first frame.
2 images: First and last frames.
3+ images: First and last frames, with intermediate images evenly spaced between.

View examples

Single frame (automatic positioning): When only one image is provided, it automatically becomes the first frame of the video.

{
  "taskType": "videoInference",
  "taskUUID": "a770f077-f413-47de-9dac-be0b26a35da6",
  "positivePrompt": "a beautiful woman walking through a garden with flowers blooming",
  "model": "klingai:5@3",
  "duration": 5,
  "width": 1920,
  "height": 1080,
  "frameImages": [
    {
      "inputImage": "aac49721-1964-481a-ae78-8a4e29b91402"
    }
  ]
}

First and last frames: With two images, they automatically become the first and last frames of the video sequence.

{
  "taskType": "videoInference",
  "taskUUID": "a770f077-f413-47de-9dac-be0b26a35da6",
  "positivePrompt": "cinematic shot of a cat playing with a ball of yarn, smooth motion",
  "model": "klingai:5@3",
  "duration": 5,
  "width": 1920,
  "height": 1080,
  "frameImages": [
    {
      "inputImage": "aac49721-1964-481a-ae78-8a4e29b91402",
      "frame": "first"
    },
    {
      "inputImage": "3ad204c3-a9de-4963-8a1a-c3911e3afafe",
      "frame": "last"
    }
  ]
}

Mixed positioning: You can combine automatic distribution with explicit frame positioning using either numeric values or named positions.

{
  "taskType": "videoInference",
  "taskUUID": "a770f077-f413-47de-9dac-be0b26a35da6",
  "positivePrompt": "time-lapse of clouds moving across a sunset sky, natural lighting",
  "model": "klingai:5@3",
  "duration": 5,
  "width": 1920,
  "height": 1080,
  "frameImages": [
    {
      "inputImage": "aac49721-1964-481a-ae78-8a4e29b91402",
      "frame": 0
    },
    {
      "inputImage": "c00abf5f-6cdb-4642-a01d-1bfff7bc3cf7",
      "frame": 48
    },
    {
      "inputImage": "3ad204c3-a9de-4963-8a1a-c3911e3afafe",
      "frame": "last"
    }
  ]
}

Array items ⁨2⁩ properties each

frameImages[] » inputImages inputImages string required

Specifies the input image that will be used to constrain the video content at the specified frame position. The image can be specified in one of the following formats:

An UUID v4 string of a previously uploaded image or a generated image.
A data URI string representing the image. The data URI must be in the format data:<mediaType>;base64, followed by the base64-encoded image. For example: data:image/png;base64,iVBORw0KGgo....
A base64 encoded image without the data URI prefix. For example: iVBORw0KGgo....
A URL pointing to the image. The image must be accessible publicly.

Supported formats are: PNG, JPG and WEBP.

frameImages[] » frame frame string | integer

Specifies the position of this frame constraint within the video timeline.

Named positions:

"first": Places the image at the beginning of the video.
"last": Places the image at the end of the video.

Numeric positions:

0: First frame (equivalent to "first").
Any positive integer: Specific frame number. Must be within the total frame count (duration × fps).

referenceImages string[]

An array containing reference images used to condition the generation process. These images provide visual guidance to help the model generate content that aligns with the style, composition, or characteristics of the reference materials.

Unlike frameImages which constrain specific timeline positions, reference images guide the general appearance that should appear consistently across the video.

Reference images work in combination with your text prompt to provide both textual and visual guidance for the generation process.

Each image can be specified in one of the following formats:

An UUID v4 string of a previously uploaded image or a generated image.
A data URI string representing the image. The data URI must be in the format data:<mediaType>;base64, followed by the base64-encoded image. For example: data:image/png;base64,iVBORw0KGgo....
A base64 encoded image without the data URI prefix. For example: iVBORw0KGgo....
A URL pointing to the image. The image must be accessible publicly.

Supported formats are: PNG, JPG and WEBP.

width integer Min: 256 Max: 1920

The width of the generated video in pixels. Must be a multiple of 8 for compatibility with video encoding standards.

Higher resolutions produce more detailed videos but require significantly more processing time and computational resources. Consider your intended use case and quality requirements when selecting dimensions.

Work within your model's supported resolution range for optimal results. Some models may have specific aspect ratio recommendations.

height integer Min: 256 Max: 1080

The height of the generated video in pixels. Must be a multiple of 8 for compatibility with video encoding standards.

Work within your model's supported resolution range for optimal results. Some models may have specific aspect ratio recommendations.

model string required

The AI model to use for video generation. Different models excel at different types of content, styles, and quality levels.

Models are identified by their AIR (Artificial Intelligence Resource) identifier in the format provider:id@version. Use the Model Search utility to discover available video models and their capabilities.

Choose models based on your desired output quality and supported features like resolution or duration limits.

duration float required Min: 1 Max: 10

The length of the generated video in seconds. This parameter directly affects the total number of frames produced based on the specified frame rate.

Total frames are calculated as duration × fps. For example, a 5-second video at 24 fps will contain 120 frames.

Longer durations require significantly more processing time and computational resources. Consider your specific use case when choosing duration length.

fps integer Min: 15 Max: 60 Default: 24

The frame rate (frames per second) of the generated video. Higher frame rates create smoother motion but require more processing time and result in larger file sizes.

Common frame rates:

24 fps: Standard cinematic frame rate, natural motion feel.
30 fps: Common for web video, smooth motion.
60 fps: High frame rate, very smooth motion for action content.

Note that using the same duration with higher frame rates creates smoother motion by generating more intermediate frames. The frame rate combines with duration to determine total frame count: duration × fps = total frames.

steps integer Min: 10 Max: 50

The number of denoising steps the model performs during video generation. More steps typically result in higher quality output but require longer processing time.

Each step refines the entire sequence, improving temporal consistency and visual quality. Higher step counts are particularly important for achieving smooth motion and reducing visual artifacts.

Most video models work well with 20-40 steps. Values below 20 may produce lower quality results, while values above 40 provide diminishing returns for most use cases.

seed integer Min: 1 Max: 9223372036854776000 Default: Random

A seed is a value used to randomize the video generation. If you want to make videos reproducible (generate the same video multiple times), you can use the same seed value.

When requesting multiple videos with the same seed, the seed will be incremented by 1 (+1) for each video generated.

CFGScale float Min: 0 Max: 50

Controls how closely the video generation follows your prompt. Higher values make the model adhere more strictly to your text description, while lower values allow more creative freedom. CFGScale affects both visual content and temporal consistency.

Recommended range is 6.0-10.0 for most video models. Values above 12 may cause over-guidance artifacts or unnatural motion patterns.

numberResults integer Min: 1 Max: 4 Default: 1

Specifies how many videos to generate for the given parameters. Each video will have the same parameters but different seeds, resulting in variations of the same concept.

If seed is set, it will be incremented by 1 (+1) for each video generated.

providerSettings object

Contains provider-specific configuration settings that customize the behavior of different AI models and services. Each provider has its own set of parameters that control various aspects of the generation process.

Currently supported providers:

google: Settings for Veo 2 and Veo 3 models.
bytedance: Settings for ByteDance's Seedance models.
minimax: Settings for MiniMax 01, MiniMax 01 Director, MiniMax 01 Live and MiniMax Hailuo 02 models.
klingai: Settings for KlingAI 1.0, KlingAI 1.5, KlingAI 1.6, KlingAI 2.0 and KlingAI 2.1 model family.
pixverse: Settings for PixVerse v3.5, PixVerse v4 and PixVerse v4.5 model family.
vidu: Settings for Vidu 1.5, Vidu 2.0, Vidu Q1 Classic and Vidu Q1 models.

The providerSettings parameter is an object that contains nested objects for each supported provider.

View example

{
  "taskType": "videoInference",
  "taskUUID": "991e641a-d2a8-4aa3-9883-9d6fe230fff8",
  "positivePrompt": "a beautiful landscape with mountains",
  "model": "google:3@0",
  "providerSettings": { 
    "google": { 
      "generateAudio": true
    } 
  } 
}

Properties ⁨12⁩ properties

providerSettings » google google object

Configuration settings specific to Google's video generation models (Veo 2 and Veo 3). These settings control various aspects of the generation process including prompt enhancement and audio generation capabilities.

View example

"providerSettings": {
  "google": { 
    "enhancePrompt": true,
    "generateAudio": false
  } 
}

Properties ⁨2⁩ properties

providerSettings » google » enhancePrompt enhancePrompt boolean Default: true

Controls whether the input prompt is automatically enhanced and expanded to improve generation quality. When enabled, the system optimizes the prompt for better results by adding relevant details and context.

This setting cannot be disabled when using Veo 3 model, as prompt enhancement is always active. For Veo 2 model, this setting can be controlled and disabled if needed.

Enhanced prompts typically result in more detailed and higher-quality video generation by providing the model with richer context and clearer instructions.

When prompt enhancement is enabled, reproducibility is not guaranteed even when using the same seed value. The enhancement process may introduce variability that affects the deterministic nature of generation.

providerSettings » google » generateAudio generateAudio boolean Default: false

Controls whether the generated video includes audio content. When enabled, the system creates appropriate audio that matches the visual content and scene context within the video.

This feature is only available for Veo 3 model. Audio generation is not supported in Veo 2.

Generated audio can include ambient sounds, music, or other audio elements that enhance the video experience and provide a more immersive result.

providerSettings » bytedance bytedance object

Configuration settings specific to ByteDance's video generation models. These settings control camera behavior and movement during video generation.

View example

"providerSettings": {
  "bytedance": { 
    "cameraFixed": false
  } 
}

Properties ⁨1⁩ property

providerSettings » bytedance » cameraFixed cameraFixed boolean Default: false

Controls whether the camera remains stationary during video generation. When enabled, the camera position and angle are fixed, preventing any camera movement, panning, or zooming effects.

When disabled (default), the model can incorporate dynamic camera movements such as pans, tilts, zooms, or tracking shots to create more cinematic and engaging video content.

This setting is useful when you need static shots or want to avoid camera motion that might distract from the main subject or action in the video.

providerSettings » minimax minimax object

Configuration settings specific to MiniMax's video generation models. These settings control prompt processing and optimization features.

View example

"providerSettings": {
  "miniMax": { 
    "promptOptimizer": false
  } 
}

Properties ⁨1⁩ property

providerSettings » minimax » promptOptimizer promptOptimizer boolean Default: false

Controls whether the input prompt is automatically optimized and refined to improve generation quality. When enabled, the system analyzes and enhances the prompt by adding relevant details, improving clarity, and optimizing structure for better video generation results.

The prompt optimizer can help transform simple or basic prompts into more detailed and effective instructions, potentially leading to higher-quality video outputs with better adherence to the intended creative vision.

When disabled, the original prompt is used as-is without any modifications or enhancements.

providerSettings » pixverse pixverse object

Configuration object for PixVerse-specific features and effects. PixVerse offers unique capabilities like viral effects, camera movements, and artistic styles that enhance video generation.

The effect and cameraMovement parameters are mutually exclusive. You can use one or the other, but not both in the same request.

View example

{
  "taskType": "videoInference",
  "taskUUID": "a770f077-f413-47de-9dac-be0b26a35da6",
  "positivePrompt": "a person dancing energetically",
  "model": "pixverse:1@3",
  "duration": 8,
  "width": 1080,
  "height": 1920,
  "providerSettings": {
    "pixverse": {
      "style": "anime",
      "effect": "jiggle jiggle",
      "motionMode": "fast",
      "watermark": false
    }
  }
}

Properties ⁨5⁩ properties

providerSettings » pixverse » style style string

Applies artistic styling to the generated video. PixVerse supports various visual aesthetics that transform the overall look and feel of the content.

Available styles:

anime: Japanese animation aesthetic with characteristic visual elements.
3d_animation: Three-dimensional animated style with depth and volume.
clay: Stop-motion clay animation appearance.
comic: Comic book or graphic novel visual style.
cyberpunk: Futuristic, neon-lit dystopian aesthetic.

The style parameter affects the entire video generation process, influencing color palettes, rendering techniques, and visual characteristics to match the selected aesthetic.

providerSettings » pixverse » effect effect string

Applies special viral effects and templates to the video content. PixVerse offers 20 unique effects designed for social media and creative content.

Available effects:

bikini up: Body transformation effect.
the tigers touch: Animal-themed transformation.
jiggle jiggle: Rhythmic movement effect.
hug your love: Romantic interaction template.
kiss me ai: Kiss interaction effect.
subject 3 fever: Energetic movement template.
fin-tastic mermaid: Mermaid transformation.
lets ymca: Dance movement template.
skeleton dance: Spooky dance effect.
kungfu club: Martial arts action template.
boom drop: Explosive impact effect.
vroom vroom step: Vehicle-themed movement.
creepy devil smile: Horror-themed facial effect.
pubg winner hit: Gaming victory celebration.
360 microwave: Spinning rotation effect.
eye zoom challenge: Close-up eye effect.
muscle surge: Body enhancement effect.
punch face: Impact reaction template.
balloon belly: Body inflation effect.
kiss kiss: Multiple kiss interaction.

Cannot be used simultaneously with cameraMovement parameter.

providerSettings » pixverse » cameraMovement cameraMovement string

Camera movements add professional cinematography techniques to your video content, making it more engaging and visually dynamic. PixVerse offers 21 cinematic camera movement options to enhance your videos with smooth, professional-looking motion.

Model compatibility: Available on PixVerse v4 and v4.5 models. Not supported on v3.5.

Available camera movements:

horizontal_lef: Smooth horizontal movement to the left.
horizontal_righ: Smooth horizontal movement to the right.
vertical_u: Vertical movement upward.
vertical_dow: Vertical movement downward.
zoom_i: Gradual zoom into the subject.
zoom_ou: Gradual zoom away from the subject.
auto_camer: Automatic camera movement based on scene content.
crane_u: Upward crane shot movement.
quickly_zoom_i: Fast zoom into the subject.
quickly_zoom_ou: Fast zoom away from the subject.
smooth_zoom_i: Gentle, smooth zoom into the subject.
camera_rotatio: Rotating camera movement around the axis.
robo_ar: Mechanical, precise camera movement.
super_dolly_ou: Dramatic outward dolly movement.
whip_pa: Quick, dynamic pan movement.
hitchcoc: Classic Hitchcock-style dolly zoom effect.
left_follo: Camera follows subject moving left.
right_follo: Camera follows subject moving right.
pan_lef: Horizontal pan to the left.
pan_righ: Horizontal pan to the right.
fix_b: Fixed background with foreground movement.

Cannot be used simultaneously with effect parameter.

providerSettings » pixverse » motionmode motionmode string Default: normal

Controls the intensity and speed of motion in the generated video.

Available modes:

normal Standard motion intensity and pacing.
fast Increased motion speed and intensity.

The fast motion mode automatically reverts to normal when duration is set to 8 seconds or when resolution is set to 1080p.

providerSettings » pixverse » watermark watermark boolean Default: false: Controls whether an "AI Generated" watermark appears on the generated video.

providerSettings » vidu vidu object

Configuration settings specific to Vidu's video generation models. These settings control movement dynamics, background music generation, and visual styles for video content.

View example

"providerSettings": {
  "vidu": { 
    "movementAmplitude": "medium",
    "bgm": true,
    "style": "anime"
  } 
}

Properties ⁨3⁩ properties

providerSettings » vidu » movementamplitude movementamplitude string Default: auto

Controls the intensity and scale of movement within the generated video content. This parameter affects how dynamic or subtle the motion appears in the final output.

Available values:

auto: Automatically determines the appropriate movement level based on the content and prompt.
small: Minimal movement with subtle animations and gentle transitions.
medium: Moderate movement with balanced dynamics.
large: High movement with pronounced animations and dramatic motion.

The movement amplitude affects elements such as camera motion, object movement, and overall scene dynamics throughout the video.

providerSettings » vidu » bgm bgm boolean Default: false

Controls whether background music is generated and included in the video content. When enabled, the model creates appropriate background music that complements the visual content and enhances the overall viewing experience.

Background music generation is only supported for 4-second videos. This feature is not available for longer video durations.

The generated background music is designed to match the mood, pace, and style of the video content automatically.

providerSettings » vidu » style style string Default: general

Specifies the visual style and artistic approach for the generated video content. This parameter influences the overall aesthetic and rendering style of the output.

Available values:

general: Standard photorealistic style suitable for most content types.
anime: Animated style with characteristic anime/manga visual elements and aesthetics.

Style selection is only supported for text-to-video generation. This parameter is not available for other video generation modes.

Response

Video inference operations require polling to retrieve results due to asynchronous processing. You'll need to use the getResponse task to check status and retrieve the final video.

When you submit a video task, you receive immediate confirmation that your request was accepted and processing has started, or an error response if validation fails.

Success

{
  "data": [
    {
      "taskType": "videoInference",
      "taskUUID": "24cd5dff-cb81-4db5-8506-b72a9425f9d1"
    }
  ]
}

Error

{
  "errors": [
    {
      "code": "unsupportedDuration",
      "message": "Invalid value for duration parameter. This duration is not supported by the model architecture.",
      "parameter": "duration",
      "type": "float",
      "documentation": "https://runware.ai/docs/en/video-inference/video-reference#request-duration",
      "taskUUID": "24cd5dff-cb81-4db5-8506-b72a9425f9d1",
      "allowedValues": [6]
    }
  ]
}

To retrieve the actual video results, use the getResponse task with the returned taskUUID. The response format depends on the current processing status:

Pending

{
  "data": [
    {
      "taskType": "videoInference",
      "taskUUID": "24cd5dff-cb81-4db5-8506-b72a9425f9d1",
      "status": "pending",
    }
  ]
}

Success

{
  "data": [
    {
      "taskType": "videoInference",
      "taskUUID": "24cd5dff-cb81-4db5-8506-b72a9425f9d1",
      "status": "success",
      "videoUUID": "b7db282d-2943-4f12-992f-77df3ad3ec71",
      "videoURL": "https://im.runware.ai/video/ws/0.5/vi/b7db282d-2943-4f12-992f-77df3ad3ec71.mp4",
      "cost": 0.18
    }
  ]
}

Error

{
  "errors": [
    {
      "code": "timeoutProvider",
      "status": "error",
      "message": "The external provider did not respond within the timeout window. The request was automatically terminated.",
      "documentation": "https://runware.ai/docs/en/video-inference/api-reference",
      "taskUUID": "24cd5dff-cb81-4db5-8506-b72a9425f9d1"
    }
  ]
}

taskType string: The API will return the taskType you sent in the request. In this case, it will be videoInference. This helps match the responses to the correct task type.

taskUUID string UUID v4: The API will return the taskUUID you sent in the request. This way you can match the responses to the correct request tasks.

videoUUID string UUID v4

A unique identifier for the generated video. This UUID can be used to reference the video in subsequent operations or for tracking purposes.

The videoUUID is different from the taskUUID. While taskUUID identifies the generation request, videoUUID identifies the specific video output.

videoURL string: If outputType is set to URL, this parameter contains the URL of the video to be downloaded.

seed integer: The seed value that was used to generate this video. This value can be used to reproduce the same video when using identical parameters in another request.

cost float: if includeCost is set to true, the response will include a cost field for each task object. This field indicates the cost of the request in USD.