FLUX.2 Klein 4B API

Compact 4B FLUX.2 model optimized for efficient generation.

Modalities
Image, TextImage
Price
$0.014per Megapixel
Model type
Image generation
Released
Jun 12, 2026

FLUX.2 Klein 4B overview

Sample FLUX.2 Klein 4B image generated through AI/ML API: A ginger cat asleep on a stack of exactly three hardcover books in a rainy bookshop window at dusk. Gold lette

FLUX.2 Klein 4B specs

Model ID
blackforestlabs/flux-2-klein-4b
Developer
Black Forest Labs
Input
Image, Text
Output
Image
Endpoint
POST https://api.aimlapi.com/v1/images/generations

Compact 4B FLUX.2 model optimized for efficient generation.

FLUX.2 Klein 4B API Pricing
- Pricing on request

High-volume image generation
Produce product visuals, thumbnails, and marketing assets programmatically at scale.

Creative and concept art
Turn text prompts into illustrations, mockups, and design explorations.

Use cases

FLUX.2 Klein 4B is documented as suited to interactive applications, real-time previews, and latency-critical production use cases.

It is also documented as suitable for content creation and rapid prototyping, especially where low-latency generation is important.

The model is documented for image generation from text descriptions, making text-to-image workflows a stated use case.

It is documented for image editing and multi-reference editing, including tasks such as inpainting, style transfer, and object manipulation.

FLUX.2 Klein 4B benchmarks by Artificial Analysis

Human-preference results for FLUX.2 Klein 4B in text to image, next to models available on AI/ML API. Data retrieved Nov 3, 2026.

Text to image

Elo · text-to-image arena

AI/ML API price

USD per Megapixel

Models on AI/ML API

Arena results for models you can call with the same API key.

Text to image

Blind pairwise human votes on images generated from text prompts. FLUX.2 Klein 4B ranks #88 of 98.

FLUX.2 Klein 4B API pricing

FLUX.2 Klein 4B pricing in US dollars
UsagePriceUnit
Image generation$0.014per Megapixel

The final price depends on request parameters such as resolution or duration.

Prices from the AI/ML API price list, checked on Nov 4, 2026.

FLUX.2 Klein 4B vs other image models: prices

AI/ML API rates for 5 models, per Megapixel.

AI/ML API prices in USD per Megapixel
ModelPer Megapixel
FLUX.2 Klein 4B$0.014
FLUX.2 Klein 9B$0.015
FLUX.2 Klein 9B Preview$0.015
FLUX.2 Pro Preview$0.03
FLUX.2 Flex$0.05

How to use the FLUX.2 Klein 4B API

View docs

Build with your agent

Give your agent the model details, code and documentation.

1Get your API key

Create API key
export AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"

2Make your first request

curl 'https://api.aimlapi.com/v1/images/generations' \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "blackforestlabs/flux-2-klein-4b",
  "prompt": "A ginger cat asleep on a stack of exactly three hardcover books in a rainy bookshop window at dusk. Gold lettering on the glass reads OPEN LATE. Warm lamp light inside, raindrops and blurred neon reflections outside, 35mm film photo."
}'

Related articles

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FLUX.2 Klein 4B FAQ

What inputs and outputs does FLUX.2 Klein 4B support?

FLUX.2 Klein 4B takes image, text as input and returns image.

When was FLUX.2 Klein 4B released?

FLUX.2 Klein 4B became available on June 12, 2026.

How much does FLUX.2 Klein 4B cost?

FLUX.2 Klein 4B costs $0.014 per Megapixel on AI/ML API, billed as you go with no subscription.

How is FLUX.2 Klein 4B billed?

FLUX.2 Klein 4B is billed per generation, a fixed charge per output rather than by prompt length.

Can FLUX.2 Klein 4B take an existing image as input?

Yes, FLUX.2 Klein 4B accepts image input as well as a text prompt.

Who created FLUX.2 Klein 4B?

FLUX.2 Klein 4B was built by Black Forest Labs.

How do I call FLUX.2 Klein 4B on AI/ML API?

Send a request to https://api.aimlapi.com/v1/images/generations with blackforestlabs/flux-2-klein-4b as the model id.

Is FLUX.2 Klein 4B available through a single API key?

Yes. FLUX.2 Klein 4B is served through AI/ML API, so the same key and endpoint format used for other models applies.

How many parameters does FLUX.2 Klein 4B have?

FLUX.2 Klein 4B is a 4 billion parameter model, as indicated by its name.

What makes FLUX.2 Klein 4B different from larger FLUX.2 models?

It is a compact 4B version of FLUX.2 built for efficient image generation.

Start building with FLUX.2 Klein 4B

FLUX.2 Klein 4B API

blackforestlabs/flux-2-klein-4b

Build with your agent

Give your agent the model details, code and documentation.

1Get your API key

Create API key
export AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"

2Make your first request

curl 'https://api.aimlapi.com/v1/images/generations' \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "blackforestlabs/flux-2-klein-4b",
  "prompt": "A ginger cat asleep on a stack of exactly three hardcover books in a rainy bookshop window at dusk. Gold lettering on the glass reads OPEN LATE. Warm lamp light inside, raindrops and blurred neon reflections outside, 35mm film photo."
}'