FLUX.1 [schnell]

AI Image Generation Model

Image $ · 0.3¢

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

1024 x 1024
Max Resolution
Supported Modes
Text to Image
Active

Details

Model ID
flux.1-schnell
Family
flux.1
Released
August 2024
Tags
image-generation text-to-image fast open-weights
// Get Started

Ready to integrate?

Access flux.1-schnell via our unified API.

Create Account
Available at 3 providers

Starting from

$0.0030 /image via fal.ai, Replicate, Runware

Prices shown are in USD

See all providers

Provider Performance

Fastest generation through fal at 2,761ms median latency with 100.0% success rate.

Aggregated from real API requests over the last 30 days.

Generation Time

fal
2,761ms p95: 4,670ms
replicate
3,236ms p95: 34,797ms
runware
3,810ms p95: 5,523ms

Success Rate

fal
100.0%
572 / 572 requests
replicate
89.5%
365 / 408 requests
runware
100.0%
513 / 513 requests

Time to First Byte

fal
1,119ms
p95: 2,557ms
replicate
1,987ms
p95: 34,298ms
runware
2,100ms
p95: 3,036ms

Provider Rankings

# Provider p50 Gen Time p95 Gen Time Success Rate TTFB (p50)
1 fal 2,761ms 4,670ms 100.0% 1,119ms
2 replicate 3,236ms 34,797ms 89.5% 1,987ms
3 runware 3,810ms 5,523ms 100.0% 2,100ms
Data updated every 15 minutes. Based on all API requests through Lumenfall over the last 30 days.

Providers & Pricing (3)

FLUX.1 [schnell] is available from 3 providers, with per-image pricing starting at $0.003 through fal.ai.

fal.ai
fal/flux.1-schnell
Provider Model ID: fal-ai/flux/schnell
$0.0030 /image
Replicate
replicate/flux.1-schnell
Provider Model ID: black-forest-labs/flux-schnell
$0.0030 /image
Runware
runware/flux.1-schnell
Provider Model ID: runware:100@1

Output

Image
$0.0030 per image
Pricing Notes (1)
  • Pricing copied from fal.ai - verify with Runware official pricing

FLUX.1 [schnell] API OpenAI-compatible

Access FLUX.1 [schnell] via Lumenfall’s OpenAI-compatible API to generate high-resolution images using a streamlined 4-step inference process tailored for low-latency applications.

Base URL
https://api.lumenfall.ai/openai/v1
Model
flux.1-schnell

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": "flux.1-schnell",
    "prompt": "",
    "size": "1024x1024"
  }'
# Response:
# { "created": 1234567890, "data": [{ "url": "https://...", "revised_prompt": "..." }] }

Parameter Reference

Required Supported Not available

Core Parameters

Parameter Type Description Modes
prompt string Required. Text prompt for image generation
T2I
negative_prompt string Negative prompt to guide generation away from undesired content
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 11 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"
670 × 1564 "670x1564" or "9:21" + "1K"
1563 × 670 "1563x670" or "21:9" + "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

Provider-specific passthrough fields, available only when the request is routed to the listed provider.

Parameter Type Description Modes
Universal
cfg_scale number Classifier-free guidance scale — higher values stick more closely to the prompt
T2I
num_inference_steps integer The number of inference steps to perform.
T2I
fal
acceleration string The speed of the generation. The higher the speed, the faster the generation.
high none regular
T2I
enable_safety_checker boolean If set to true, the safety checker will be enabled.
T2I
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.
T2I
replicate
disable_safety_checker boolean Disable safety checker for generated images.
T2I
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.
T2I
megapixels string Approximate number of megapixels for generated image
0.25 1
T2I
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
T2I
runware
height integer Output image height in pixels. FLUX dimensions must be from 128 to 2048 pixels and divisible by 64.
T2I
outputType string How Runware returns generated image data.
URL base64Data dataURI
T2I
width integer Output image width in pixels. FLUX dimensions must be from 128 to 2048 pixels and divisible by 64.
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.

FLUX.1 [schnell] Benchmarks

FLUX.1 [schnell] is ranked #49 in Text-to-Image with an Elo of 1192 on the Lumenfall Arena, where real users pick the better image in blind comparisons. These rankings are based on 3 blind-vote competitions.

Lumenfall Arena
#49
Text-to-Image
1192 Elo

Text-to-Image Landscape

Competition Results

Text-to-Image

Prompt Adherence

View leaderboard
#32
Geometric Composition
70 models
Text-to-Image
Prompt

“A glass cube on a wooden table. Inside the cube is a small blue sphere. On top of the cube sits a red book. A green plant is behind the cube, partially visible through the glass. Soft window light from the left.”

#18
The Capybara Taxi Driver
69 models
Text-to-Image
Prompt

“Photorealistic scene inside a yellow New York taxi at night. A capybara is driving, wearing a yellow taxi driver cap and a dark jacket. It has a calm, professional expression and both front paws on the steering wheel. In the back seat sits a human businesswoman in a coat, looking at her phone with a completely normal, bored expression (as if this is just another normal ride). Through the windows you can see the streets of Manhattan at night with blurred lights. Realistic taxi interior, photorealistic, detailed fur and fabric, 35mm lens, night lighting with reflections, shallow depth of field.”

#20
Chalkboard Menu
69 models
Text-to-Image
Prompt

“Handwritten-style chalkboard menu in a cozy café, all text rendered in the exact same realistic chalk handwriting style with natural variations in letter size, slight slant, and chalk texture — no printed or digital fonts anywhere on the board. Title at the top in elegant cursive chalk handwriting: ‘TODAY’S SPECIALS – APRIL 30, 2026’. Below it, three menu items also in the same handwritten chalk style: ‘Truffle Mushroom Risotto – $24’, ‘Grilled Octopus with Lemon & Herbs – $28’, ‘Brown Butter Chocolate Chip Cookies – $9’. At the very bottom, smaller text in the identical handwritten chalk style (slightly smaller but still clearly legible with the same handwriting characteristics): ‘All items made fresh daily • Ask about our gluten-free options’. Warm ambient café lighting, visible chalk dust and smudges, realistic handwriting imperfections, no clean printed text anywhere.”

Text-to-Image

Aesthetics

View leaderboard
#32
Geometric Composition
70 models
Text-to-Image
Prompt

“A glass cube on a wooden table. Inside the cube is a small blue sphere. On top of the cube sits a red book. A green plant is behind the cube, partially visible through the glass. Soft window light from the left.”

#18
The Capybara Taxi Driver
69 models
Text-to-Image
Prompt

“Photorealistic scene inside a yellow New York taxi at night. A capybara is driving, wearing a yellow taxi driver cap and a dark jacket. It has a calm, professional expression and both front paws on the steering wheel. In the back seat sits a human businesswoman in a coat, looking at her phone with a completely normal, bored expression (as if this is just another normal ride). Through the windows you can see the streets of Manhattan at night with blurred lights. Realistic taxi interior, photorealistic, detailed fur and fabric, 35mm lens, night lighting with reflections, shallow depth of field.”

Text-to-Image

Photorealism

View leaderboard
#32
Geometric Composition
70 models
Text-to-Image
Prompt

“A glass cube on a wooden table. Inside the cube is a small blue sphere. On top of the cube sits a red book. A green plant is behind the cube, partially visible through the glass. Soft window light from the left.”

#18
The Capybara Taxi Driver
69 models
Text-to-Image
Prompt

“Photorealistic scene inside a yellow New York taxi at night. A capybara is driving, wearing a yellow taxi driver cap and a dark jacket. It has a calm, professional expression and both front paws on the steering wheel. In the back seat sits a human businesswoman in a coat, looking at her phone with a completely normal, bored expression (as if this is just another normal ride). Through the windows you can see the streets of Manhattan at night with blurred lights. Realistic taxi interior, photorealistic, detailed fur and fabric, 35mm lens, night lighting with reflections, shallow depth of field.”

#20
Chalkboard Menu
69 models
Text-to-Image
Prompt

“Handwritten-style chalkboard menu in a cozy café, all text rendered in the exact same realistic chalk handwriting style with natural variations in letter size, slight slant, and chalk texture — no printed or digital fonts anywhere on the board. Title at the top in elegant cursive chalk handwriting: ‘TODAY’S SPECIALS – APRIL 30, 2026’. Below it, three menu items also in the same handwritten chalk style: ‘Truffle Mushroom Risotto – $24’, ‘Grilled Octopus with Lemon & Herbs – $28’, ‘Brown Butter Chocolate Chip Cookies – $9’. At the very bottom, smaller text in the identical handwritten chalk style (slightly smaller but still clearly legible with the same handwriting characteristics): ‘All items made fresh daily • Ask about our gluten-free options’. Warm ambient café lighting, visible chalk dust and smudges, realistic handwriting imperfections, no clean printed text anywhere.”

Text-to-Image

Text Rendering

View leaderboard
#20
Chalkboard Menu
69 models
Text-to-Image
Prompt

“Handwritten-style chalkboard menu in a cozy café, all text rendered in the exact same realistic chalk handwriting style with natural variations in letter size, slight slant, and chalk texture — no printed or digital fonts anywhere on the board. Title at the top in elegant cursive chalk handwriting: ‘TODAY’S SPECIALS – APRIL 30, 2026’. Below it, three menu items also in the same handwritten chalk style: ‘Truffle Mushroom Risotto – $24’, ‘Grilled Octopus with Lemon & Herbs – $28’, ‘Brown Butter Chocolate Chip Cookies – $9’. At the very bottom, smaller text in the identical handwritten chalk style (slightly smaller but still clearly legible with the same handwriting characteristics): ‘All items made fresh daily • Ask about our gluten-free options’. Warm ambient café lighting, visible chalk dust and smudges, realistic handwriting imperfections, no clean printed text anywhere.”

Text-to-Image

Product, Branding & Commercial

View leaderboard
#20
Chalkboard Menu
69 models
Text-to-Image
Prompt

“Handwritten-style chalkboard menu in a cozy café, all text rendered in the exact same realistic chalk handwriting style with natural variations in letter size, slight slant, and chalk texture — no printed or digital fonts anywhere on the board. Title at the top in elegant cursive chalk handwriting: ‘TODAY’S SPECIALS – APRIL 30, 2026’. Below it, three menu items also in the same handwritten chalk style: ‘Truffle Mushroom Risotto – $24’, ‘Grilled Octopus with Lemon & Herbs – $28’, ‘Brown Butter Chocolate Chip Cookies – $9’. At the very bottom, smaller text in the identical handwritten chalk style (slightly smaller but still clearly legible with the same handwriting characteristics): ‘All items made fresh daily • Ask about our gluten-free options’. Warm ambient café lighting, visible chalk dust and smudges, realistic handwriting imperfections, no clean printed text anywhere.”

Text-to-Image

3D Imaging & Modeling

View leaderboard
#32
Geometric Composition
70 models
Text-to-Image
Prompt

“A glass cube on a wooden table. Inside the cube is a small blue sphere. On top of the cube sits a red book. A green plant is behind the cube, partially visible through the glass. Soft window light from the left.”

Top Matchups

See how FLUX.1 [schnell] performs head-to-head against other AI models, ranked by community votes in blind comparisons.

Help rank FLUX.1 [schnell] Pick the better image in blind matchups. Results update rankings in real time.
Start Voting

FLUX.1 [schnell] FAQ

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, Runware, and Replicate 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.

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.

Try FLUX.1 [schnell] in Playground

Generate images with custom prompts — no API key needed.

Open Playground