What Is FLUX.2 Klein 4B?
FLUX.2 Klein 4B is Black Forest Labs’ smallest fully open FLUX.2 model. It is built for interactive and high-volume generation, uses only four to eight inference steps and can run on substantially more accessible hardware than the larger FLUX tiers.
FLUX Model Versions
FLUX.2 Klein 4B
4–8 steps · 2K
From 1 Credits
FLUX.2 Klein
Fastest · 1K
From 1 Credits
FLUX.2 Max
The highest-fidelity FLUX.2 tier for final-publish generation and demanding prompt adherence.
- Resolutions: 1K / 2K
- Reference images: not supported
- Modes: Text to Image, Typography
- Speed: Balanced
FLUX.2 Flex
FLUX.2 with explicit guidance and step controls for typography-heavy final renders.
- Resolutions: 1K / 2K
- Reference images: not supported
- Modes: Text to Image
- Speed: Balanced
FLUX.2 Flash
A low-cost FLUX.2 route for rapid generation and exact multi-reference edits.
- Resolutions: 1K / 2K
- Reference images: up to 4
- Modes: Text to Image, Edit Image, Multi-reference
- Speed: Fastest
FLUX.2 Turbo
A fast FLUX.2 draft model with prompt expansion and unusually low megapixel cost.
- Resolutions: 1K / 2K
- Reference images: up to 4
- Modes: Text to Image, Image to Image, Edit Image, Multi-reference
- Speed: Fastest
FLUX.2 Klein 4B
Black Forest Labs’ fully open compact FLUX.2 model for high-volume and interactive generation.
- Resolutions: 1K / 2K
- Reference images: not supported
- Modes: Text to Image
- Speed: Fastest
FLUX.1 Kontext Max
The premium Kontext tier for typography, prompt adherence and identity-preserving edits.
- Resolutions: 1K
- Reference images: up to 1
- Modes: Text to Image, Image to Image, Edit Image
- Speed: Balanced
FLUX.1 Kontext Pro
Fast, context-aware generation and iterative editing from a single reference.
- Resolutions: 1K
- Reference images: up to 1
- Modes: Text to Image, Image to Image, Edit Image
- Speed: Fast
FLUX1.1 Pro Ultra
The high-resolution FLUX1.1 Pro tier for natural photography, detailed materials and reference-guided renders.
- Resolutions: 2K
- Reference images: up to 1
- Modes: Text to Image, Image to Image
- Speed: Balanced
FLUX1.1 Pro
The production FLUX1.1 endpoint for detailed photographic and material-rich final renders.
- Resolutions: 1K / 2K
- Reference images: not supported
- Modes: Text to Image
- Speed: Balanced
FLUX.1 Dev
The tunable FLUX.1 development checkpoint for prompt experiments, seeded studies and controllable rendering.
- Resolutions: 1K / 2K
- Reference images: not supported
- Modes: Text to Image
- Speed: Slow
FLUX.1 Schnell
The original open FLUX speed tier for rapid four-step concepts and inexpensive prompt batches.
- Resolutions: 1K
- Reference images: not supported
- Modes: Text to Image, Typography
- Speed: Fastest
FLUX.2
Realistic light and material detail, with every parameter exposed.
- Resolutions: 1K / 2K / 4K
- Reference images: up to 4
- Modes: Text to Image, Image to Image, Edit Image
- Speed: Balanced
FLUX.2 Klein
The distilled FLUX.2: speed first, same visual language.
- Resolutions: 1K
- Reference images: up to 1
- Modes: Text to Image, Image to Image
- Speed: Fastest
What Is FLUX.2 Klein 4B Best For?
- Near-real-time concepting
- High-volume image batches
- Local and open-weight workflows
- Fast photographic drafts
How to Use FLUX.2 Klein 4B
- Write a visually concrete prompt.
- Start at four steps and 1K.
- Increase to eight only if the layout is incomplete.
- Use a larger FLUX model for the final when needed.
FLUX.2 Klein 4B Settings Explained
Steps
Four is the speed-first default; eight is the endpoint maximum for difficult prompts.
Resolution
The low per-megapixel route makes 2K inexpensive, but 1K remains fastest.
The panel above shows only the parameters FLUX.2 Klein 4B actually supports. Switch versions and unsupported controls disappear rather than sitting there doing nothing.
FLUX.2 Klein 4B Prompt Examples
Rapid product draft
Compact wireless speaker in translucent cobalt plastic, white studio sweep, crisp commercial lighting, subtle shadow
Environment concept
Rain-soaked elevated train platform at dawn, soft mist, commuters in silhouette, grounded cinematic photography
FLUX.2 Klein 4B Test Results
Testing in progress
Every model runs the same eight-category prompt set — portrait, product, poster text, anime character, interior, multi-reference, image editing and character consistency — recording generation time, success rate, text accuracy and identity retention. That run has not finished for FLUX.2 Klein 4B, so this page shows no scores. We do not publish numbers we have not measured.
FLUX.2 Klein 4B Limitations
- Text-to-image only on this hosted route
- Less detail than larger FLUX.2 tiers
- Four to eight steps leaves little value in manual over-tuning
FLUX.2 Klein 4B Pricing and Credits
Credits scale with resolution and image count. The Generate button always shows what this run costs.
1K
1 credits / image
2K
1 credits / image
Failed generations cost 0 credits.
Commercial Use and Image Rights
FLUX.2 Klein 4B weights are released under Apache 2.0; generated use remains subject to applicable law and service terms.
- Model used: FLUX.2 Klein 4B
- Model developer: Black Forest Labs
- The inference route is managed internally and may change without changing the selected model
- Uploads are sent only to the configured inference service needed to complete the generation
- You can delete any generation from your history at any time
Frequently Asked Questions
Is 4B commercially usable?+
Black Forest Labs releases the 4B weights under Apache 2.0.
How is it different from Klein 9B?+
4B is faster, smaller and fully Apache-licensed; 9B trades more compute for stronger quality.
Model Updates and Changelog
- 2026-08-25 —— Added a dedicated 4B page and exact four-to-eight-step request mapping.
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