How do I generate quickly with FLUX.2 [klein]?

FLUX.2 [klein] - Fast Generation Guide

FLUX.2 [klein] is our fastest model family, delivering state-of-the-art image quality with fastest inference times. It's designed for applications requiring real-time generation.

Two Variants

Feature

[klein] 4B

[klein] 9B

VRAM Required

~13GB

~24GB

License

Apache 2.0

(fully open)

FLUX Non-Commercial

Commercial Use

Yes (free)

Licensing

+ API only

API Price (base)

$0.014

$0.015

Multi-reference

Up to 4 images

Up to 4 images

Running Locally

Both [klein] variants are available for local deployment via

Hugging Face

:

[klein] 4B

- Apache 2.0 license allows full commercial use locally

[klein] 9B

- Non-commercial local use; commercial use requires API

Base variants

- Undistilled models available for fine-tuning and customization

Prompting Tips for [klein]

Important:

[klein] does not include prompt upsampling. For best results:

Use narrative prompting

- Describe scenes like a novelist, not keyword lists

Be specific

- Include details about lighting, composition, style

Include context

- Describe the setting, mood, and atmosphere

Example prompt:

"A weathered fisherman mends his nets on a wooden dock at golden hour. His calloused hands work methodically while seagulls circle overhead. The warm light catches the spray of salt water in the air, creating a hazy, nostalgic atmosphere."

Supported Features

Text-to-image

- Generate from text descriptions

Image editing

- Modify existing images with prompts

Multi-reference

- Up to 4 reference images

Exact color matching

- Use hex codes like

#02eb3c

in prompts

Resolution

- 64x64 to 4MP (dimensions must be multiples of 16)

What [klein] Does NOT Support

Prompt upsampling (write detailed prompts manually)

Grounding search (exclusive to [max])

More than 4 reference images

API Usage

Endpoints:

POST /v1/flux-2-klein-4b

POST /v1/flux-2-klein-9b

For complete API documentation, see

docs.bfl.ai/flux_2/flux2_text_to_image