# FLUX.1 [schnell]

> Black Forest Labs' 12 billion parameter distilled image generation model optimized for speed, capable of generating high-quality images in just 4 inference steps

## Quick Reference

- Model ID: flux.1-schnell
- Creator: Black Forest Labs
- Status: active
- Family: flux.1
- Base URL: https://api.lumenfall.ai/openai/v1

## Specifications

- Max Resolution: 1024x1024
- Input Modalities: text
- Output Modalities: image
- Supported Modes: Text to Image

## API Parameters

The compiled parameter schema for this model is available via the API: `GET /v1/models/flux.1-schnell?schema=true`.

### Core Parameters

- `prompt` (string) — REQUIRED: Text prompt for image generation
- `seed` (integer): Random seed for reproducibility

### Size & Layout

- `size` (string): Image dimensions as WxH pixels (e.g. "1024x1024") or aspect ratio (e.g. "16:9"). Values: 1563x670, 670x1564, 1365x768, 768x1365, 1254x836, 836x1254, 887x1182, 1024x1024, 1145x916, 916x1145, 1183x887
- `aspect_ratio` (string): Aspect ratio of the output image (e.g. "16:9", "1:1"). Values: 9:21, 9:16, 2:3, 3:4, 4:5, 1:1, 5:4, 4:3, 3:2, 16:9, 21:9
- `resolution` (string): Output resolution tier (e.g. "1K", "4K"). Values: 1K

### Output & Format

- `response_format` (string): How to return the image. Default: url. Values: url, b64_json
- `output_format` (string): Output image format. Values: png, jpeg, gif, webp, avif
- `output_compression` (integer): Compression level for lossy formats (JPEG, WebP, AVIF)
- `n` (integer): Number of images to generate. Default: 1

### Additional Parameters

- `cfg_scale` (number): Classifier-free guidance scale — higher values stick more closely to the prompt
- `acceleration` (string): The speed of the generation. The higher the speed, the faster the generation.. Values: high, none, regular. Only available via fal
- `disable_safety_checker` (boolean): Disable safety checker for generated images.. Only available via replicate
- `enable_safety_checker` (boolean): If set to true, the safety checker will be enabled.. Only available via fal
- `go_fast` (boolean): Run faster predictions with model optimized for speed (currently fp8 quantized); disable to run in original bf16. Note that outputs will not be deterministic when this is enabled, even if you set a seed.. Only available via replicate
- `megapixels` (string): Approximate number of megapixels for generated image. Values: 0.25, 1. Only available via replicate
- `num_inference_steps` (integer): The number of inference steps to perform.
- `output_quality` (integer): Quality when saving the output images, from 0 to 100. 100 is best quality, 0 is lowest quality. Not relevant for .png outputs. Only available via replicate
- `sync_mode` (boolean): If `True`, the media will be returned as a data URI and the output data won't be available in the request history.. Only available via fal


## Model Identifiers

- Primary Slug: flux.1-schnell


## Tags

image-generation, text-to-image, fast, open-weights

## Available Providers

### fal.ai

- Config Key: fal/flux.1-schnell
- Provider Model ID: fal-ai/flux/schnell
- Pricing: $0.0030/image
  - Source: https://fal.ai/models/fal-ai/flux/schnell

### Replicate

- Config Key: replicate/flux.1-schnell
- Provider Model ID: black-forest-labs/flux-schnell
- Pricing: $0.0030/image
  - Source: https://replicate.com/black-forest-labs/flux-schnell

### Runware

- Config Key: runware/flux.1-schnell
- Provider Model ID: runware:100@1
- Pricing: $0.0030/image
  - Note: Pricing copied from fal.ai - verify with Runware official pricing


## Image Gallery

2 images available for this model. Browse all at https://lumenfall.ai/models/black-forest-labs/flux.1-schnell/gallery

### Curated Examples

- [Cinematic 16:9 wide shot of a high-end, contemporary coffee shop interior at golden hour. The sun...](https://assets.lumenfall.ai/Iw9yG6sU_MVbDATLQ3602iQCGAEzi7nh1LEQiHo3V2c/rs:fit:1500:1500/plain/gs://lumenfall-prod-assets/bjexq026mje5kgis2gg6z7kq5rzt@jpeg)
- [A cozy roadside fruit stand with a chalkboard sign that reads "FRESH PEACHES" in elegant cursive....](https://assets.lumenfall.ai/hNb6OYYcMwGbvClE2KCNMHopAUn9FA2wtca986CLZ4Q/rs:fit:1500:1500/plain/gs://lumenfall-prod-assets/61bqgsau5x9t258iqvlreyp1vvmw@jpeg)

## Example Prompt

The following prompt was used to generate an example image in our playground:

A cozy roadside fruit stand with a chalkboard sign that reads "FRESH PEACHES" in elegant cursive. Golden hour lighting, crates of vibrant fruit, and a calm capybara sitting quietly in the soft shadows behind the counter. High detail, 4k.

## Code Examples

### Text to Image (/v1/images/generations)

#### cURL

curl -X POST \
  https://api.lumenfall.ai/openai/v1/images/generations \
  -H "Authorization: Bearer $LUMENFALL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "flux.1-schnell",
    "prompt": "",
    "size": "1024x1024"
  }'

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

#### JavaScript

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: 'flux.1-schnell',
  prompt: '',
  size: '1024x1024'
});

// { created: 1234567890, data: [{ url: "https://...", revised_prompt: "..." }] }
console.log(response.data[0].url);

#### Python

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://api.lumenfall.ai/openai/v1"
)

response = client.images.generate(
    model="flux.1-schnell",
    prompt="",
    size="1024x1024"
)

# { created: 1234567890, data: [{ url: "https://...", revised_prompt: "..." }] }
print(response.data[0].url)


## About

## Overview
FLUX.1 [schnell] is a 12 billion parameter text-to-image model developed by Black Forest Labs, designed specifically for low-latency image generation. As the distilled version of the FLUX.1 family, it produces high-fidelity visuals in significantly fewer steps than traditional diffusion models. It is an open-weights model that balances large-scale parameter density with extreme inference efficiency.

## Strengths
*   **Inference Speed:** Capable of generating high-resolution images in as few as 1 to 4 inference steps, making it one of the fastest high-parameter models currently available.
*   **Text Rendering:** High accuracy in rendering legible, correctly spelled text within generated images, a common failure point for many latent diffusion models.
*   **Anatomical Precision:** Maintains strong structural integrity in complex subjects, such as human hands and limbs, even at low step counts.
*   **Prompt Adherence:** Follows complex, multi-part descriptive prompts closely, ensuring that specific spatial relationships and attributes defined in the text are reflected in the output.

## Limitations
*   **Photorealistic Detail:** While the model is fast, it may lack the fine-grained texture and lighting nuances found in the [pro] or [dev] versions of FLUX.1 which use more inference steps.
*   **Stylistic Range:** The distillation process can sometimes lead to a slightly more uniform "digital" aesthetic compared to non-distilled models that allow for more creative variance.
*   **Compositional Fixedness:** Due to the low step count, the model has less "time" to refine compositions during sampling, which can occasionally lead to artifacts in highly crowded scenes.

## Technical Background
The model is built on a 12-billion parameter architecture that utilizes flow matching, a generative modeling technique that simplifies the path from noise to data. The [schnell] variant (German for "fast") uses latent adversarial diffusion distillation to compress the capabilities of the larger FLUX.1 base into a regime that requires minimal sampling iterations. This architecture allows it to bypass the traditional requirement of 20-50 steps common in standard diffusion pipelines.

## Best For
FLUX.1 [schnell] is ideal for real-time applications, rapid prototyping, and high-volume generation tasks where cost and speed are prioritized over maximum artistic refinement. It is particularly effective for generating UI mockups, social media assets, and iterative design brainstorming. You can experiment with FLUX.1 [schnell] using Lumenfall’s unified API and playground to compare its performance against slower, more intensive image models.

## Frequently Asked Questions

### How much does FLUX.1 [schnell] cost?

FLUX.1 [schnell] starts at $0.003 per image through Lumenfall. Pricing varies by provider. Lumenfall does not add any markup to provider pricing.

### How do I use FLUX.1 [schnell] via API?

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

### Which providers offer FLUX.1 [schnell]?

FLUX.1 [schnell] is available through fal.ai, Replicate, and Runware on Lumenfall. Lumenfall automatically routes requests to the best available provider.

### What is the maximum resolution for FLUX.1 [schnell]?

FLUX.1 [schnell] supports images up to 1024x1024 resolution.

## Links

- Model Page: https://lumenfall.ai/models/black-forest-labs/flux.1-schnell
- About: https://lumenfall.ai/models/black-forest-labs/flux.1-schnell/about
- Providers, Pricing & Performance: https://lumenfall.ai/models/black-forest-labs/flux.1-schnell/providers
- API Reference: https://lumenfall.ai/models/black-forest-labs/flux.1-schnell/api
- Benchmarks: https://lumenfall.ai/models/black-forest-labs/flux.1-schnell/benchmarks
- Use Cases: https://lumenfall.ai/models/black-forest-labs/flux.1-schnell/use-cases
- Gallery: https://lumenfall.ai/models/black-forest-labs/flux.1-schnell/gallery
- Playground: https://lumenfall.ai/playground?model=flux.1-schnell
- API Documentation: https://docs.lumenfall.ai