Black Forest Labs: FLUX.2 [klein] 4B Base
flux-2-klein-4b-base- Price
- From $0.0019
- Modalities
- Image
About FLUX.2 [klein] 4B Base
FLUX.2 [klein] 4B Base is the undistilled version of Black Forest Labs' smallest FLUX.2 model, with 4 billion parameters for text-to-image and multi-reference editing. Unlike the step-distilled klein 4B, it keeps the full training signal, which gives more varied outputs and a better starting point for fine-tuning, at the cost of needing many more sampling steps.
Where it works well
- It is undistilled, so it keeps the complete training signal and is the intended base for LoRA training and custom post-training.
- Black Forest Labs reports higher output diversity than the distilled klein models, useful when you want many different takes on one prompt.
- At 4 billion parameters it fits in roughly 13GB of VRAM, within reach of consumer GPUs for local experiments.
- Weights use Apache 2.0, the most permissive license in the FLUX.2 family.
When to choose another model
- Its default sampling uses about fifty steps, so it is slower per image than the step-distilled klein 4B.
- Text inside images can come out distorted, and the maker warns that prompt adherence depends on phrasing.
- The larger FLUX.2 [dev] and 9B models handle complex scenes and reference blends with more capacity.
Getting started
Create API key
Create a key in Console, then use it with every model on the platform.
Send your first request
Copy the example for your language and run it against the endpoint.
Image editingText to imageTokenLab endpointPOST/v1/images/generationscurl -X POST "https://api.tokenlab.sh/v1/images/generations" \ -H "Authorization: Bearer sk-xxx" \ -H "Content-Type: application/json" \ -d '{ "operation": "image-to-image", "model": "flux-2-klein-4b-base", "prompt": "A minimalist product photo of matte black headphones on a soft blue background.", "image_url": "https://example.com/source.png" }'
Pricing
Official price is the model maker's public baseline. TokenLab price is what you pay for this model on TokenLab.
Image editing
per request- Official price
- $0.0019
- Official
- $0.0019
- Discount
- —
Text to image
per request- Official price
- $0.0019
- Official
- $0.0019
- Discount
- —
| Official priceper request | Officialper request | Discount | |
|---|---|---|---|
| Image editing | $0.0019 | $0.0019 | — |
| Text to image | $0.0019 | $0.0019 | — |
Usage & activity
Success rate is the share of requests that completed. Latency is how long a full response takes; P95 means 95% of requests finished within that time.
Usage & availability
Last 24 hours- Requests
- Success rate
- P95 latency
- Total tokens
Data is based on aggregate user requests, excluding status checks.
Open in Console
Open FLUX.2 [klein] 4B Base in Console with a prompt ready to edit or send.
Help me create an image with flux-2-klein-4b-base using image-edit at /v1/images/edits. Show the result, cost, and any limits I should know.
Use cases
Best for- Text to Image
Fine-tuning a house style
Train a LoRA on a few hundred brand images, starting from a base that has not been compressed by distillation.
Generating varied candidates
Produce many different interpretations of one brief for a designer to pick from, benefiting from the wider spread of outputs.
Research on small image models
Use it as the reference point when measuring what distillation or a new training recipe changes.
Light editing pipelines
Run text-to-image and reference-based edits through one small model inside a custom workflow.
Prompt examples
A watercolor map of a fictional harbor town, muted teal and ochre, hand-lettered feel, no legible text.
Four different logo directions for a bakery called Crumb, flat vector style, one color each.
Take the sofa from the reference photo and show it in a sunlit Scandinavian living room.
FAQ
What does Base mean in FLUX.2 [klein] 4B Base?
Base means undistilled. The checkpoint keeps the full training signal rather than being compressed into a few-step sampler, so it is more flexible for customization and gives more diverse outputs, but it is not tuned for the fastest inference.
How is it different from FLUX.2 [klein] 4B?
The plain 4B is step-distilled for speed and can return an image in under a second. The 4B Base needs far more sampling steps and is meant for training, research, and cases where output variety matters more than latency.
Can I use FLUX.2 [klein] 4B Base commercially?
The weights are released under Apache 2.0, which permits commercial use of the model and its outputs. Check the license text and the maker's usage policy for any conditions that apply to your deployment.
Does it support image editing?
Yes. Black Forest Labs describes the klein family as a unified architecture for text-to-image and multi-reference editing, and the 4B Base inherits both abilities, so a single checkpoint can serve generation and edit requests alike.
Which GPU does it need for self-hosting?
The model card gives about 13GB of VRAM as the minimum, which covers cards in the RTX 3090 and 4070 class. That requirement only matters if you run the weights yourself.
How much does FLUX.2 [klein] 4B Base cost?
On TokenLab, FLUX.2 [klein] 4B Base costs $0.0019 per request. The pricing table above shows the full breakdown. Rates depend on the billing unit, specification, and usage. Compare matching conditions in the model's detailed pricing; a single rate does not determine the total cost.
Which endpoint should FLUX.2 [klein] 4B Base use?
Use https://api.tokenlab.sh/v1/images/edits for FLUX.2 [klein] 4B Base. The request example below shows the matching code shape.
Which operations does FLUX.2 [klein] 4B Base support?
FLUX.2 [klein] 4B Base supports Image editing, Text to image. Select an operation above to see its endpoint and request example.
Compare FLUX.2 [klein] 4B Base
Sources
Reviewed Oct 2, 2026
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