Flux 1 Schnell

bfl/flux-1/schnell

Flux 1 Schnell by BFL - generate stunning images from text prompts with state-of-the-art AI. Supports multiple aspect ratios, styles, and high-resolution output for creative and commercial use.

Try the model

Playground

Open playground

Input

Prompt(string)

The prompt to generate an image from.

Additional Settings More

Customize your input with more control.

Aspect Ratio(string)

The aspect ratio of the generated image. Allowed values: 21:9, 16:9, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 9:16.

Guidance scale (CFG)(number)

120

The CFG (Classifier Free Guidance) scale is a measure of how close you want the model to stick to your prompt when looking for a related image to show you. Range: 1 to 20.

Num Inference Steps(integer)

112

The number of inference steps to perform. Range: 1 to 12.

Output Format(string)

The format of the generated image. Allowed values: jpeg, png.

Seed(integer)

The same seed and the same prompt given to the same version of the model will output the same image every time.

Result

Example

What would you like to do next?
Open original

Examples

Select an example to load its inputs and result into the playground.

Input

{
  "aspect_ratio": "1:1",
  "num_inference_steps": 1,
  "output_format": "jpeg",
  "prompt": "A simple blue circle centered on a white background. QA test.",
  "seed": 20261006
}

Open result ↗

Human preference

Arena

Elo ratings from blind side-by-side votes, compared with other image and video models.

Rankings sourced from Artificial Analysis Arena

Leaderboard: Text to Image
Rank: #104 of 106
Elo: 740 ±20
Gap to #1: −482

Text-to-image arena: people pick the better of two images generated from the same prompt, without seeing the model names.

#97Phoenix 0.9 UltraLeonardo.Ai833±20
#98Phoenix 1.0 FastLeonardo.Ai827±20
#99SRPOTencent826±20
#100FLUX.1 [dev]Black Forest Labs823±45
#101FIBO LiteBria813±16
#102HiDream-O1-Image-DevHiDreamOn SandBase810±20
#103Luma Photon FlashLuma Labs769±23
#104FLUX.1 [schnell]Black Forest LabsThis model740±20
#105OmniGen V2VectorSpaceLab717±26
#106BagelBytedance594±35

Flux 1 Schnell

FLUX.1 [schnell] generates an image in 1–4 steps, the cheapest FLUX option for quick drafts.

Fields

Field	Type	Default	Notes
`prompt`	string, required	—	Text instruction.
`aspect_ratio`	`21:9` / `16:9` / `3:2` / `4:3` / `5:4` / `1:1` / `4:5` / `3:4` / `2:3` / `9:16`	`16:9`	Output shape.
`guidance_scale`	number 1–20	3.5	How strictly to follow the prompt.
`num_inference_steps`	integer 1–12	4	More steps add detail and time.
`output_format`	`jpeg` / `png`	`jpeg`	Output file format.
`seed`	integer	random	Fix it to compare prompt changes.

Billing

$0.003 per image.

Request	Price
One image	$0.003

Failed runs are not charged.

Prompting

Keep prompts short and concrete.

Limits

One image per request.

Also on SandBase

Related: bfl/flux-2/klein/4b (newer, fast).

Start building

Send your first request

Submit this model through the SandBase Unified Run API.

Production API

Unified Run API endpoint

https://api.sandbase.ai/v1/run

Model ID

bfl/flux-1/schnell

# The quoted heredoc keeps Unicode and shell metacharacters unchanged.
result=$(curl --fail-with-body --silent \
  -X POST "https://api.sandbase.ai/v1/run" \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'SANDBASE_JSON'
{
  "model": "bfl/flux-1/schnell",
  "prompt": "Extreme close-up of a single tiger eye, direct frontal view. Detailed iris and pupil. Sharp focus on eye texture and color. Natural lighting to capture authentic eye shine and depth. The word \"FLUX\" is painted over it in big, white brush strokes with visible texture.",
  "aspect_ratio": "16:9",
  "output_format": "jpeg",
  "guidance_scale": 3.5,
  "num_inference_steps": 4
}
SANDBASE_JSON
)
run_id=$(printf '%s' "$result" | jq -r .id)
for attempt in $(seq 1 120); do
  status=$(printf '%s' "$result" | jq -r .status)
  case "$status" in completed|failed|timeout) break ;; esac
  sleep 2
  result=$(curl --fail-with-body --silent \
    -H "Authorization: Bearer $SANDBASE_API_KEY" \
    "https://api.sandbase.ai/v1/run/$run_id")
done
status=$(printf '%s' "$result" | jq -r .status)
[ "$status" = completed ] || { echo "Generation ended: $status" >&2; exit 1; }
printf '%s\n' "$result"

2. Authentication

Create a SandBase API key and set it in your server environment. All requests use Bearer authentication.

API key environment variable

export SANDBASE_API_KEY="YOUR_API_KEY"

Keep the key on your server. Do not expose it in browser code or commit it to a repository.

3. Queue

Submit a request

POST to /v1/run with this model ID and its inputs. The request example above includes submission and polling.

Fetch request status and result

Use the returned run ID to poll until the status is completed, failed or timeout. Read output only after completed.

Poll run status

curl "https://api.sandbase.ai/v1/run/$RUN_ID" \
  -H "Authorization: Bearer $SANDBASE_API_KEY"

4. Files

Hosted files

Pass a publicly accessible file URL in the model’s image, video or audio field. Supported formats and limits are shown beside each Playground input.

Uploading images

Use the upload or replace control on supported image fields in the Playground. Video URL fields accept a hosted driving video; they do not imply video-upload support.

5. Schema

Input

`seed`integer

The same seed and the same prompt given to the same version of the model will output the same image every time.

`prompt`stringrequired

The prompt to generate an image from.

`aspect_ratio`string

The aspect ratio of the generated image.

Default: "16:9"

Possible values: "21:9", "16:9", "3:2", "4:3", "5:4", "1:1", "4:5", "3:4", "2:3", "9:16"

`output_format`string

The format of the generated image.

Default: "jpeg"

Possible values: "jpeg", "png"

`guidance_scale`number

The CFG (Classifier Free Guidance) scale is a measure of how close you want the model to stick to your prompt when looking for a related image to show you.

Default: 3.5

Minimum: 1

Maximum: 20

`num_inference_steps`integer

The number of inference steps to perform.

Default: 4

Minimum: 1

Maximum: 12

Request body

{
  "model": "bfl/flux-1/schnell",
  "prompt": "Extreme close-up of a single tiger eye, direct frontal view. Detailed iris and pupil. Sharp focus on eye texture and color. Natural lighting to capture authentic eye shine and depth. The word \"FLUX\" is painted over it in big, white brush strokes with visible texture.",
  "aspect_ratio": "16:9",
  "output_format": "jpeg",
  "guidance_scale": 3.5,
  "num_inference_steps": 4
}

Output

A completed run exposes its result in output. The following is the model’s saved example, not a new generation.

Example output JSON

[
  {
    "source": "Completed user prediction (human visual safety screened)",
    "source_url": "https://www.sandbase.ai",
    "url": "https://static.sandbase.ai/examples/2bb648d2-b3fe-4fd9-ac9e-353707e8f7b5/output/a45e26b1-ee6b-4418-bbc0-0fa60c50fff4.jpg"
  }
]

Flux 1 Schnell

Playground

Examples

Arena

Flux 1 Schnell

Fields

Billing

Prompting

Limits

Also on SandBase

Send your first request

2. Authentication

3. Queue

Submit a request

Fetch request status and result

4. Files

Hosted files

Uploading images

5. Schema

Input

seedinteger

promptstringrequired

aspect_ratiostring

output_formatstring

guidance_scalenumber

num_inference_stepsinteger

Output

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`seed`integer

`prompt`stringrequired

`aspect_ratio`string

`output_format`string

`guidance_scale`number

`num_inference_steps`integer