---
title: FLUX.1 Expand [pro] | Runware Docs
url: https://runware.ai/docs/models/bfl-flux-1-expand-pro
description: High fidelity FLUX outpainting for seamless image expansion
---
# FLUX.1 Expand [pro]

FLUX.1 Expand [pro] is an outpainting model that extends images beyond their original frame while preserving structure, lighting, and style. It supports controlled expansion from real or generated inputs and integrates into image editing or generative workflows that need precise, coherent borders.

- **ID**: `bfl:1@3`
- **Status**: live
- **Creator**: Black Forest Labs
- **Release Date**: November 21, 2024
- **Capabilities**: Image to Image

## Request Parameters

**API Options**

Platform-level options for task execution and delivery.

### [taskType](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-tasktype)

- **Type**: `string`
- **Required**: true
- **Value**: `imageInference`

Identifier for the type of task being performed

### [taskUUID](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-taskuuid)

- **Type**: `string`
- **Required**: true
- **Format**: `UUID v4`

UUID v4 identifier for tracking tasks and matching async responses. Must be unique per task.

### [outputType](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-outputtype)

- **Type**: `string`
- **Default**: `URL`

Image output type.

**Allowed values**: `URL` `base64Data` `dataURI`

### [outputFormat](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-outputformat)

- **Type**: `string`
- **Default**: `JPG`

Specifies the file format of the generated output. The available values depend on the task type and the specific model's capabilities.

- \`JPG\`: Best for photorealistic images with smaller file sizes (no transparency).
- \`PNG\`: Lossless compression, supports high quality and transparency (alpha channel).
- \`WEBP\`: Modern format providing superior compression and transparency support.

> [!NOTE]
> \*\*Transparency\*\*: If you are using features like background removal or LayerDiffuse that require transparency, you must select a format that supports an alpha channel (e.g., \`PNG\`, \`WEBP\`, \`TIFF\`). \`JPG\` does not support transparency.

**Allowed values**: `JPG` `PNG` `WEBP`

### [outputQuality](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-outputquality)

- **Type**: `integer`
- **Min**: `20`
- **Max**: `99`
- **Default**: `95`

Compression quality of the output. Higher values preserve quality but increase file size.

### [webhookURL](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-webhookurl)

- **Type**: `string`
- **Format**: `URI`

Specifies a webhook URL where JSON responses will be sent via HTTP POST when generation tasks complete. For batch requests with multiple results, each completed item triggers a separate webhook call as it becomes available.

**Learn more** (1 resource):

- [Webhooks](https://runware.ai/docs/platform/webhooks) (platform)

### [deliveryMethod](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-deliverymethod)

- **Type**: `string`
- **Default**: `sync`

Determines how the API delivers task results.

**Allowed values**:

- `sync` Returns complete results directly in the API response.
- `async` Returns an immediate acknowledgment with the task UUID. Poll for results using getResponse.

**Learn more** (1 resource):

- [Task Polling](https://runware.ai/docs/platform/task-polling) (platform)

### [uploadEndpoint](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-uploadendpoint)

- **Type**: `string`
- **Format**: `URI`

Specifies a URL where the generated content will be automatically uploaded using the HTTP PUT method. The raw binary data of the media file is sent directly as the request body. For secure uploads to cloud storage, use presigned URLs that include temporary authentication credentials.

**Common use cases:**

- **Cloud storage**: Upload directly to S3 buckets, Google Cloud Storage, or Azure Blob Storage using presigned URLs.
- **CDN integration**: Upload to content delivery networks for immediate distribution.

```text
// S3 presigned URL for secure upload
https://your-bucket.s3.amazonaws.com/generated/content.mp4?X-Amz-Signature=abc123&X-Amz-Expires=3600

// Google Cloud Storage presigned URL
https://storage.googleapis.com/your-bucket/content.jpg?X-Goog-Signature=xyz789

// Custom storage endpoint
https://storage.example.com/uploads/generated-image.jpg
```

The content data will be sent as the request body to the specified URL when generation is complete.

### [safety](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-safety)

- **Path**: `safety.checkContent`
- **Type**: `object (2 properties)`

Content safety checking configuration for image generation.

#### [checkContent](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-safety-checkcontent)

- **Path**: `safety.checkContent`
- **Type**: `boolean`
- **Default**: `false`

Enable or disable content safety checking. When enabled, defaults to `fast` mode.

#### [mode](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-safety-mode)

- **Path**: `safety.mode`
- **Type**: `string`
- **Default**: `none`

Safety checking mode for image generation.

**Allowed values**:

- `none` Disables checking.
- `fast` Performs a single check.

### [ttl](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-ttl)

- **Type**: `integer`
- **Min**: `60`

Time-to-live (TTL) in seconds for generated content. Only applies when `outputType` is `URL`.

### [includeCost](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-includecost)

- **Type**: `boolean`
- **Default**: `false`

Include task cost in the response.

### [numberResults](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-numberresults)

- **Type**: `integer`
- **Min**: `1`
- **Max**: `20`
- **Default**: `1`

Number of results to generate. Each result uses a different seed, producing variations of the same parameters.

**Inputs**

Input resources for the task (images, audio, etc). These must be nested inside the \`inputs\` object.

### [seedImage](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-inputs-seedimage)

- **Path**: `inputs.seedImage`
- **Type**: `string`
- **Required**: true

Image used as a starting point for the generation (UUID, URL, Data URI, or Base64).

**Learn more** (3 resources):

- [Image To Image: Seed Image The Foundation](https://runware.ai/docs/guides/image-to-image#seed-image-the-foundation) (guide)
- [Image Inpainting: Seed And Mask Image The Foundation](https://runware.ai/docs/guides/image-inpainting#seed-and-mask-image-the-foundation) (guide)
- [Image Outpainting: Seed Image The Starting Point](https://runware.ai/docs/guides/image-outpainting#seed-image-the-starting-point) (guide)

**Generation Parameters**

Core parameters for controlling the generated content.

### [model](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-model)

- **Type**: `string`
- **Required**: true
- **Value**: `bfl:1@3`

Identifier of the model to use for generation.

**Learn more** (3 resources):

- [Text To Image: Model Selection The Foundation Of Generation](https://runware.ai/docs/guides/text-to-image#model-selection-the-foundation-of-generation) (guide)
- [Image Inpainting: Model Specialized Inpainting Models](https://runware.ai/docs/guides/image-inpainting#model-specialized-inpainting-models) (guide)
- [Image Outpainting: Other Critical Parameters](https://runware.ai/docs/guides/image-outpainting#other-critical-parameters) (guide)

### [positivePrompt](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-positiveprompt)

- **Type**: `string`
- **Required**: true
- **Min**: `2`
- **Max**: `3000`

Text prompt describing elements to include in the generated output.

**Learn more** (2 resources):

- [Text To Image: Prompts Guiding The Generation](https://runware.ai/docs/guides/text-to-image#prompts-guiding-the-generation) (guide)
- [Image Outpainting: Other Critical Parameters](https://runware.ai/docs/guides/image-outpainting#other-critical-parameters) (guide)

### [steps](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-steps)

- **Type**: `integer`
- **Min**: `15`
- **Max**: `50`
- **Default**: `50`

Total number of denoising steps. Higher values generally produce more detailed results but take longer.

**Learn more** (1 resource):

- [Text To Image: Steps Trading Quality For Speed](https://runware.ai/docs/guides/text-to-image#steps-trading-quality-for-speed) (guide)

### [CFGScale](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-cfgscale)

- **Type**: `float`
- **Min**: `1.5`
- **Max**: `100`
- **Step**: `0.01`
- **Default**: `60`

Guidance scale representing how closely the output will resemble the prompt. Higher values produce results more aligned with the prompt.

**Learn more** (1 resource):

- [Text To Image: Cfg Scale Balancing Creativity And Control](https://runware.ai/docs/guides/text-to-image#cfg-scale-balancing-creativity-and-control) (guide)

### [outpaint](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-outpaint)

- **Path**: `outpaint.bottom`
- **Type**: `object (4 properties)`
- **Required**: true

Extends image boundaries in specified directions. Final width/height must account for original image plus extensions.

**Learn more** (1 resource):

- [Image Outpainting: Outpaint Defining The Expansion](https://runware.ai/docs/guides/image-outpainting#outpaint-defining-the-expansion) (guide)

#### [bottom](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-outpaint-bottom)

- **Path**: `outpaint.bottom`
- **Type**: `integer`
- **Min**: `0`
- **Max**: `2048`
- **Step**: `64`

Number of pixels to extend to the bottom.

#### [left](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-outpaint-left)

- **Path**: `outpaint.left`
- **Type**: `integer`
- **Min**: `0`
- **Max**: `2048`
- **Step**: `64`

Number of pixels to extend to the left.

#### [right](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-outpaint-right)

- **Path**: `outpaint.right`
- **Type**: `integer`
- **Min**: `0`
- **Max**: `2048`
- **Step**: `64`

Number of pixels to extend to the right.

#### [top](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-outpaint-top)

- **Path**: `outpaint.top`
- **Type**: `integer`
- **Min**: `0`
- **Max**: `2048`
- **Step**: `64`

Number of pixels to extend to the top.

**Provider Settings**

Parameters specific to this model provider. These must be nested inside the \`providerSettings.bfl\` object.

### [promptUpsampling](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-providersettings-bfl-promptupsampling)

- **Path**: `providerSettings.bfl.promptUpsampling`
- **Type**: `boolean`
- **Default**: `false`

Enable automatic enhancement and expansion of the input prompt.

### [safetyTolerance](https://runware.ai/docs/models/bfl-flux-1-expand-pro#request-providersettings-bfl-safetytolerance)

- **Path**: `providerSettings.bfl.safetyTolerance`
- **Type**: `integer`
- **Min**: `0`
- **Max**: `6`
- **Default**: `2`

Tolerance level for content moderation. Lower values are stricter; higher values are more permissive.

## Response Parameters

### [taskType](https://runware.ai/docs/models/bfl-flux-1-expand-pro#response-tasktype)

- **Type**: `string`
- **Required**: true
- **Value**: `imageInference`

Type of the task.

### [taskUUID](https://runware.ai/docs/models/bfl-flux-1-expand-pro#response-taskuuid)

- **Type**: `string`
- **Required**: true
- **Format**: `UUID v4`

UUID of the task.

### [imageUUID](https://runware.ai/docs/models/bfl-flux-1-expand-pro#response-imageuuid)

- **Type**: `string`
- **Required**: true
- **Format**: `UUID v4`

UUID of the output image.

### [imageURL](https://runware.ai/docs/models/bfl-flux-1-expand-pro#response-imageurl)

- **Type**: `string`
- **Format**: `URI`

URL of the output image.

### [imageBase64Data](https://runware.ai/docs/models/bfl-flux-1-expand-pro#response-imagebase64data)

- **Type**: `string`

Base64-encoded image data.

### [imageDataURI](https://runware.ai/docs/models/bfl-flux-1-expand-pro#response-imagedatauri)

- **Type**: `string`
- **Format**: `URI`

Data URI of the output image.

### [seed](https://runware.ai/docs/models/bfl-flux-1-expand-pro#response-seed)

- **Type**: `integer`

The seed used for generation. If none was provided, shows the randomly generated seed.

### [NSFWContent](https://runware.ai/docs/models/bfl-flux-1-expand-pro#response-nsfwcontent)

- **Type**: `boolean`

Flag indicating if NSFW content was detected.

### [cost](https://runware.ai/docs/models/bfl-flux-1-expand-pro#response-cost)

- **Type**: `float`

Task cost in USD. Present when `includeCost` is set to `true` in the request.

## Examples

### Moonlit Marsh Caravan Encampment (Image to Image)

![Moonlit Marsh Caravan Encampment](https://assets.runware.ai/examples/bfl-flux-1-expand-pro/b7694fcd-4ce0-4610-bb67-10396af24d25.jpg)

**Request**:

```json
{
  "taskType": "imageInference",
  "taskUUID": "567a4534-6ee4-464a-8a66-3ba4be47cd3e",
  "model": "bfl:1@3",
  "positivePrompt": "Expand the scene outward into a broad moonlit marsh landscape surrounding the existing caravan encampment. Preserve the original wagon, mule, travelers, firelight, and cool lunar illumination. Add winding reflective water channels, clumps of reeds, distant cypress silhouettes, low drifting mist, scattered bedrolls and travel crates near the camp, faint wheel tracks fading into wet ground, a far treeline, and a dramatic open sky with layered clouds around a bright moon. Maintain realistic cinematic detail, natural perspective, seamless continuity, and balanced negative space around the central camp.",
  "steps": 40,
  "CFGScale": 55,
  "outpaint": {
    "left": 384,
    "right": 384,
    "top": 256,
    "bottom": 256
  },
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/552fdf32-900e-434b-8f50-ad876925ccc8.jpg"
  }
}
```

**Response**:

```json
{
  "taskType": "imageInference",
  "taskUUID": "567a4534-6ee4-464a-8a66-3ba4be47cd3e",
  "imageUUID": "1b2519f3-5b22-4a54-89c2-c0a53e43e592",
  "imageURL": "https://im.runware.ai/image/os/a16d07/ws/2/ii/1b2519f3-5b22-4a54-89c2-c0a53e43e592.jpg",
  "seed": 2141894651,
  "cost": 0.05
}
```

---

### Grand Aquarium Rotunda Expansion (Image to Image)

![Grand Aquarium Rotunda Expansion](https://assets.runware.ai/examples/bfl-flux-1-expand-pro/aef1f578-526c-40ec-ba40-fcf388e3c9d2.jpg)

**Request**:

```json
{
  "taskType": "imageInference",
  "taskUUID": "9a48ce30-8355-4b7f-9e15-617b5f8a4fd7",
  "model": "bfl:1@3",
  "positivePrompt": "Expand the existing aquarium rotunda beyond the original frame with seamless architectural continuity: more sweeping arches, vaulted ceiling ribs, suspended directional signs, additional cylindrical side tanks, reflective stone flooring, benches, distant visitors, subtle refractions from the water, soft teal glow balanced with warm interior lighting, realistic perspective lines, refined high-end public space design, richly detailed but natural, cohesive materials and shadows, photographic realism",
  "steps": 40,
  "CFGScale": 55,
  "outpaint": {
    "left": 384,
    "right": 384,
    "top": 256,
    "bottom": 320
  },
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/10ab549f-109e-4c55-b256-e18aa74c6f1d.jpg"
  }
}
```

**Response**:

```json
{
  "taskType": "imageInference",
  "taskUUID": "9a48ce30-8355-4b7f-9e15-617b5f8a4fd7",
  "imageUUID": "c41386bd-a690-4215-94ea-5271c72c1524",
  "imageURL": "https://im.runware.ai/image/os/a05d22/ws/2/ii/c41386bd-a690-4215-94ea-5271c72c1524.jpg",
  "seed": 1556062672,
  "cost": 0.05
}
```

---

### Glacial Viaduct Panorama Expansion (Image to Image)

![Glacial Viaduct Panorama Expansion](https://assets.runware.ai/examples/bfl-flux-1-expand-pro/c6c32192-64f0-41d6-8bbb-b72754fa8ca0.jpg)

**Request**:

```json
{
  "taskType": "imageInference",
  "taskUUID": "22ed3e04-4497-4e68-a3b5-61811c85a92e",
  "model": "bfl:1@3",
  "positivePrompt": "Extend the existing glacier-valley viaduct scene into a grand panoramic vista. Preserve the original bridge, train, scale, perspective, and blue-hour dawn lighting. Reveal towering snow-covered peaks beyond the current frame, additional fractured ice fields below, wind-carved ridges, faint alpine clouds catching pale pink sunlight, and deeper valley depth on both sides. Keep the image photorealistic, cinematic, crisp, and geographically believable, with seamless continuation of stone texture, rail lines, mist layers, shadows, and atmospheric depth.",
  "steps": 40,
  "CFGScale": 55,
  "outpaint": {
    "top": 512,
    "left": 384,
    "right": 384,
    "bottom": 256
  },
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/c41d1e74-79ec-4066-8e6a-ac529129eba1.jpg"
  }
}
```

**Response**:

```json
{
  "taskType": "imageInference",
  "taskUUID": "22ed3e04-4497-4e68-a3b5-61811c85a92e",
  "imageUUID": "b84d218b-4907-42eb-b0b8-754e212912e0",
  "imageURL": "https://im.runware.ai/image/os/a10d08/ws/2/ii/b84d218b-4907-42eb-b0b8-754e212912e0.jpg",
  "seed": 1238429443,
  "cost": 0.05
}
```

---

### Cliffside Monastery Dawn Expansion (Image to Image)

![Cliffside Monastery Dawn Expansion](https://assets.runware.ai/examples/bfl-flux-1-expand-pro/bd042fbe-20f6-46ec-88e7-cfcfd47fa3bb.jpg)

**Request**:

```json
{
  "taskType": "imageInference",
  "taskUUID": "f6f41d51-db5f-45ce-8b36-89c9860a9602",
  "model": "bfl:1@3",
  "positivePrompt": "Expand the scene outward into a grand panoramic mountain sanctuary. Preserve the original cliffside monastery, stone materials, perspective, and soft dawn light. Add vast surrounding rock walls, layered alpine peaks fading into the distance, a winding path chiselled into the cliffs, suspended rope bridges, sparse wind-shaped pines, low valley mist, subtle birds circling far away, and golden sunlight catching ridgelines. Keep the image realistic, serene, majestic, and compositionally seamless with natural atmospheric perspective.",
  "steps": 40,
  "CFGScale": 55,
  "outpaint": {
    "left": 512,
    "right": 512,
    "top": 256,
    "bottom": 256
  },
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/e968767b-577b-4e44-aab2-922c656d5470.jpg"
  }
}
```

**Response**:

```json
{
  "taskType": "imageInference",
  "taskUUID": "f6f41d51-db5f-45ce-8b36-89c9860a9602",
  "imageUUID": "ef43418c-8f03-4fcc-9509-635e2737d651",
  "imageURL": "https://im.runware.ai/image/os/a11d13/ws/2/ii/ef43418c-8f03-4fcc-9509-635e2737d651.jpg",
  "seed": 367135997,
  "cost": 0.05
}
```