FLUX1.1 [pro]

Name: FLUX1.1 [pro]
Brand: Black Forest Labs
Price: 0.04 USD
Availability: InStock

AI Image Generation Model

Image

Black Forest Labs' enhanced 12-billion parameter flow transformer with 6x faster generation than FLUX.1 [pro], delivering superior composition, detail, and artistic fidelity

Try Model

2048 x 2048

Max Resolution

Supported Modes

Text to Image

Active

Details

Model ID

flux1.1-pro

Also known as: flux-pro-1.1

Creator

Black Forest Labs

Family

flux1.1

Ready to integrate?

Access flux1.1-pro via our unified API.

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Available at 2 providers

Starting from

$0.040 /image via fal.ai, Replicate

Prices shown are in USD

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Providers & Pricing (2)

FLUX1.1 [pro] is available from 2 providers, with per-image pricing starting at $0.04 through fal.ai.

fal.ai

fal/flux1.1-pro

Provider Model ID: fal-ai/flux-pro/v1.1

$0.040 /image

View pricing details

Replicate

replicate/flux1.1-pro

Provider Model ID: black-forest-labs/flux-1.1-pro

$0.040 /image

View pricing details

flux-pro-1.1 API OpenAI-compatible

Integrate FLUX1.1 [pro] via Lumenfall's OpenAI-compatible API to generate professional-grade images 6x faster than previous flow transformer iterations.

Base URL

https://api.lumenfall.ai/openai/v1

Model

flux1.1-pro

Code Examples

Text to Image

/v1/images/generations

curl -X POST \

  https://api.lumenfall.ai/openai/v1/images/generations \

  -H "Authorization: Bearer $LUMENFALL_API_KEY" \

  -H "Content-Type: application/json" \

  -d '{

    "model": "flux1.1-pro",

    "prompt": "",

    "size": "1024x1024"

}'

# Response:

# { "created": 1234567890, "data": [{ "url": "https://...", "revised_prompt": "..." }] }

import OpenAI from 'openai';

const client = new OpenAI({

  apiKey: 'YOUR_API_KEY',

  baseURL: 'https://api.lumenfall.ai/openai/v1'

});

const response = await client.images.generate({

  model: 'flux1.1-pro',

  prompt: '',

  size: '1024x1024'

});

// { created: 1234567890, data: [{ url: "https://...", revised_prompt: "..." }] }

console.log(response.data[0].url);

from openai import OpenAI

client = OpenAI(

    api_key="YOUR_API_KEY",

    base_url="https://api.lumenfall.ai/openai/v1"

response = client.images.generate(

    model="flux1.1-pro",

    prompt="",

    size="1024x1024"

# { created: 1234567890, data: [{ url: "https://...", revised_prompt: "..." }] }

print(response.data[0].url)

Parameter Reference

Required Supported Not available

Core Parameters

Parameter	Type	Description	Modes
`prompt`	string	Required. Text prompt for image generation	T2I
`seed`	integer	Random seed for reproducibility	T2I

Size & Layout

Parameter	Type	Description	Modes
`size`	string	Image dimensions as WxH pixels (e.g. "1024x1024") or aspect ratio (e.g. "16:9") WxH determines both shape and scale (aspect_ratio and resolution are ignored when size is provided). W:H format is equivalent to aspect_ratio.	T2I
`aspect_ratio`	string	Aspect ratio of the output image (e.g. "16:9", "1:1") Controls shape independently of scale. Use with resolution to control both. If size is also provided, size takes precedence. Any ratio is accepted and mapped to the nearest supported value.	T2I
`resolution`	string	Output resolution tier (e.g. "1K", "4K") `1K` Controls scale independently of shape. Higher tiers produce larger images and cost more. If size is also provided, size takes precedence for scale. Any tier is accepted and mapped to the nearest supported value.	T2I

Output	`size`		`aspect_ratio` + `resolution`
Flexible
Custom 1–14142px per side	`"WxH"`	—	Any pixel dimensions within model constraints

1K 9 sizes

Output	`size`		`aspect_ratio` + `resolution`
1183 × 887	`"1183x887"`	or	`"4:3"` + `"1K"`
916 × 1145	`"916x1145"`	or	`"4:5"` + `"1K"`
1145 × 916	`"1145x916"`	or	`"5:4"` + `"1K"`
1024 × 1024	`"1024x1024"`	or	`"1:1"` + `"1K"`
887 × 1182	`"887x1182"`	or	`"3:4"` + `"1K"`
836 × 1254	`"836x1254"`	or	`"2:3"` + `"1K"`
1254 × 836	`"1254x836"`	or	`"3:2"` + `"1K"`
768 × 1365	`"768x1365"`	or	`"9:16"` + `"1K"`
1365 × 768	`"1365x768"`	or	`"16:9"` + `"1K"`

How these parameters work

size

Exact pixel dimensions

"1920x1080"

aspect_ratio

Shape only, default scale

"16:9"

resolution

Scale tier, preserves shape

"1K"

Priority when combined

size › aspect_ratio + resolution › aspect_ratio › resolution

size is most specific and always wins. aspect_ratio and resolution control shape and scale independently.

How matching works

Shape matching – we pick the closest supported ratio. Ask for 7:1 on a model with 4:1 and 8:1, you get 8:1.

Scale matching – providers use different tier formats: K tiers (0.5K 1K 2K 4K) or megapixel tiers (0.25 1). If the exact tier isn't available, you get the nearest one.

Dimension clamping – if a model has pixel limits, we clamp dimensions to fit and keep the aspect ratio intact.

Output & Format

Parameter	Type	Description	Modes
`response_format`	string	How to return the image `url` `b64_json` Default: `"url"`	T2I
`output_format`	string	Output image format `png` `jpeg` `gif` `webp` `avif` Gateway converts to requested format if provider doesn't support it natively.	T2I
`output_compression`	integer	Compression level for lossy formats (JPEG, WebP, AVIF)	T2I
`n`	integer	Number of images to generate Default: `1` Gateway generates multiple images in parallel even if provider only supports 1.	T2I

Additional Parameters

Parameter	Type	Description	Modes
`enhance_prompt` fal	boolean	Whether to enhance the prompt for better results.	T2I
`height` replicate	integer	Height of the generated image in text-to-image mode. Only used when aspect_ratio=custom. Must be a multiple of 32 (if it's not, it will be rounded to nearest multiple of 32). Note: Ignored in img2img and inpainting modes.	T2I
`image_prompt` replicate	string	Image to use with Flux Redux. This is used together with the text prompt to guide the generation towards the composition of the image_prompt. Must be jpeg, png, gif, or webp.	T2I
`output_quality` replicate	integer	Quality when saving the output images, from 0 to 100. 100 is best quality, 0 is lowest quality. Not relevant for .png outputs	T2I
`prompt_upsampling` replicate	boolean	Automatically modify the prompt for more creative generation	T2I
`safety_tolerance`	string	The safety tolerance level for the generated image. 1 being the most strict and 5 being the most permissive. `1` `2` `3` `4` `5` `6`	T2I
`sync_mode` fal	boolean	If `True`, the media will be returned as a data URI and the output data won't be available in the request history.	T2I
`width` replicate	integer	Width of the generated image in text-to-image mode. Only used when aspect_ratio=custom. Must be a multiple of 32 (if it's not, it will be rounded to nearest multiple of 32). Note: Ignored in img2img and inpainting modes.	T2I

Parameter Normalization

How we handle parameters across different providers

Not every provider speaks the same language. When you send a parameter, we handle it in one of four ways depending on what the model supports:

Behavior	What happens	Example
`passthrough`	Sent as-is to the provider	style, quality
`renamed`	Same value, mapped to the field name the provider expects	prompt
`converted`	Transformed to the provider's native format	size
`emulated`	Works even if the provider has no concept of it	n, response_format

Parameters we don't recognize pass straight through to the upstream API, so provider-specific options still work.

Full API Reference Authentication, endpoints, and more

Gallery

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FLUX1.1 [pro] FAQ

How much does FLUX1.1 [pro] cost?

FLUX1.1 [pro] starts at $0.04 per image through Lumenfall. Pricing varies by provider. Lumenfall does not add any markup to provider pricing.

How do I use FLUX1.1 [pro] via API?

You can use FLUX1.1 [pro] through Lumenfall's OpenAI-compatible API. Send requests to the unified endpoint with model ID "flux1.1-pro". Code examples are available in Python, JavaScript, and cURL.

Which providers offer FLUX1.1 [pro]?

FLUX1.1 [pro] is available through fal.ai and Replicate on Lumenfall. Lumenfall automatically routes requests to the best available provider.

What is the maximum resolution for FLUX1.1 [pro]?

FLUX1.1 [pro] supports images up to 2048x2048 resolution.

Overview

FLUX1.1 [pro] is a high-performance text-to-image model developed by Black Forest Labs, designed to balance elite output quality with rapid generation speeds. It is an evolution of the FLUX.1 architecture, utilizing a 12-billion parameter flow transformer to produce high-resolution imagery six times faster than its predecessor. This model is engineered for professional workflows that require high-fidelity details, precise prompt adherence, and efficient batch processing.

Strengths

Generation Velocity: Provides a 6x speed increase over the original FLUX.1 [pro], significantly reducing latency for high-resolution image synthesis.
Instruction Adherence: Excels at interpreting complex, multi-subject prompts with high spatial accuracy and compositional integrity.
Anatomical and Textual Accuracy: Demonstrates superior rendering of fine details, including realistic human anatomy (particularly hands) and legible, coherent text within generated images.
Artistic Versatility: Balances photorealistic output with the ability to execute various aesthetic styles, from cinematic photography to digital illustration, without losing detail.

Limitations

Hardware and Cost Requirements: As a “pro” tier model with 12 billion parameters, it requires substantial computational resources and carries a higher cost per generation ($0.04) compared to smaller “schnell” or “dev” variants.
Fixed Modality: The model is currently focused strictly on text-to-image generation and does not natively support multi-modal inputs like image-to-image or video out-of-the-box without specialized pipeline implementations.

Technical Background

FLUX1.1 [pro] is built on a “flow transformer” architecture, a design that optimizes the diffusion process by modeling the straight-line paths between data and noise. This iteration focuses on refined sampling efficiency, allowing the model to reach high-convergence states in fewer steps than traditional diffusion models. The training emphasizes high-parameter density to capture intricate textures and global scene coherence.

Best For

FLUX1.1 [pro] is ideal for commercial design projects, advertising assets, and any professional application where speed-to-market and visual precision are critical. It is particularly effective for generating marketing copy embedded in imagery or high-fidelity character concept art. Developers can access FLUX1.1 [pro] through Lumenfall’s unified API and interactive playground, enabling rapid testing and integration into production-ready creative pipelines.

Try FLUX1.1 [pro] in Playground

Generate images with custom prompts — no API key needed.

Open Playground