Flux 2 Klein 4B Edit

bfl/flux-2/klein/4b/edit

Flux 2 Klein 4b by BFL - AI-powered image editing, style transfer, and transformation. Edit photos with natural language instructions, remove backgrounds, change styles, and enhance images effortlessly.

Base price
$0.02USD / run
Execution
async
Model type
image
Input fields
6
Production route

Try the model

Playground

Open playground
Input
The prompt to edit the image.

PNG, JPEG, WebP, or GIF · 20 MiB maximum each

The URLs of the images for editing. A maximum of 4 images are allowed.
48
The number of inference steps to perform. Range: 4 to 8.
The format of the generated image. Allowed values: jpeg, png.
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.
The seed to use for the generation. If not provided, a random seed will be used.
OutputExample

Examples

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

Model card

Specifications

Pricing

Base price
$0.02 / run

Context & modalities

Input
Schema-defined
Output
image

Capabilities

Chat
Not supported
Vision
Not supported
Reasoning
Not supported
Structured output
Not supported
Function calling
Not supported
Audio input
Not supported

Access

Provider
BFL
Model ID
bfl/flux-2/klein/4b/edit
Execution
async
Base URL
https://api.sandbase.ai
API
Unified Run API
Endpoint
/v1/run

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
Image Editing
Rank
#63 of 77
Elo
938 ±17
Gap to #1
−261

Image-editing arena: people pick the better of two edits of the same image and instruction, without seeing the model names.

  1. #58Qwen Image Edit Plus 2509Alibaba965±18
  2. #59HiDream-O1-ImageHiDream954±14
  3. #60Kling Image 3.0 OmniKlingAIOn SandBase952±14
  4. #61Vidu Q2Vidu951±18
  5. #62Kling Image O1KlingAI944±14
  6. #63FLUX.2 [klein] 4BBlack Forest LabsThis model938±17
  7. #64GPT Image 1 Mini (medium)OpenAIOn SandBase934±19
  8. #65FLUX.1 Kontext [max]Black Forest Labs932±19
  9. #66FLUX.1 Kontext [pro]Black Forest Labs916±19
  10. #67FIBO EditBria915±19

API README

Flux 2 Klein 4B Edit

FLUX.2 [klein] 4B, the smallest FLUX.2 model, built for speed. Edit or combine images with an instruction.

Fields

FieldTypeDefaultNotes
promptstring, required—Text instruction.
imagesimage URL[]—Images to edit or combine, Image 1, Image 2, …
num_inference_stepsinteger 4–84More steps add detail and time.
output_formatjpeg / pngpngOutput file format.
aspect_ratio21:9 / 16:9 / 3:2 / 4:3 / 5:4 / 1:1 / 4:5 / 3:4 / 2:3 / 9:16—Output shape.
seedintegerrandomFix it to compare prompt changes.

Billing

$0.02 per image.

RequestPrice
One image$0.02

Failed runs are not charged.

Prompting

  • Say which image is the base and what each other image contributes.
  • List what must not change.

Limits

  • One output image per request.

Also on SandBase

Other FLUX.2 endpoints: bfl/flux-2/max/edit, bfl/flux-2/pro/edit, bfl/flux-2/flex/edit, bfl/flux-2/dev/edit, bfl/flux-2/klein/4b.

Start building

Send your first request

OpenAI-compatible endpoint with unified authentication and usage tracking.

Production API
Unified Run API endpoint
https://api.sandbase.ai/v1/run
Model ID
bfl/flux-2/klein/4b/edit
# 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 $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'SANDBASE_JSON'
{
  "model": "bfl/flux-2/klein/4b/edit",
  "images": [
    "https://static.sandbase.ai/examples/bfl/flux-2/klein/4b/edit/input_images_0.png"
  ],
  "prompt": "Turn this into a realistic image",
  "output_format": "png",
  "num_inference_steps": 4
}
SANDBASE_JSON
)
run_id=$(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"

Choose your model

Compare models

All image & video models
ModelTypeDefault priceReleased
BFLImage$0.02 / runJan 15, 2026
BFLImage$0.05 / runOct 1, 2026
BFLImage$0.05 / runOct 1, 2026
BFLImage$0.02 / runJan 15, 2026
BFLImage$0.01 / runJan 15, 2026
BFLImage$0.01 / runJan 15, 2026

Questions

FAQ

How do I call BFL Flux 2 Klein 4B Edit through SandBase?

Create a SandBase API key, then send requests with the model ID "bfl/flux-2/klein/4b/edit" to Unified Run API (/v1/run) at https://api.sandbase.ai. The request examples on this page show the exact payload.

Do I need a separate BFL account?

No. One SandBase API key and balance gives you access to BFL Flux 2 Klein 4B Edit and the other models in the catalog; you do not need to sign up with BFL separately.