black-forest-labs
Black Forest Labs: FLUX.2 Klein 4B
black-forest-labs/flux.2-klein-4b
Our take
AI-assisted analysis based on the sources below. Suitability is an editorial assessment; test it on your own workload.
black-forest-labs/flux.2-klein-4b is a four-billion-parameter rectified-flow transformer from Black Forest Labs that generates images from text and edits images using multiple references. Its model card describes it as a compact, distilled FLUX.2 Klein variant aimed at sub-second interactive generation and local use on consumer GPUs with roughly 13 GB of VRAM. OpenRouter lists it as a text-and-image to image endpoint and provides design-arena results; those are measured catalog listings, not vendor quality claims.[1][2]
Strengths
- Combines text-to-image generation and multi-reference image editing in one compact checkpoint.[2]
- The vendor describes it as a distilled model for sub-second interactive inference and says it can run on consumer GPUs with about 13 GB of VRAM.[2]
- Open weights are available for commercial use under Apache 2.0, and the card documents reference code plus Diffusers, ComfyUI, and BFL API access.[2]
Limitations
- The card says rendered text may be inaccurate or distorted, outputs can miss the prompt, and prompt adherence depends heavily on prompting style.[2]
- It is not intended to provide factual information and, as a statistical model, may reproduce or amplify biases from its training data.[2]
- The supplied evidence is one vendor model card plus an OpenRouter listing; measured results are limited to design-arena categories, so latency, quality, cost, and safety-filter behavior still need workload-specific validation.[1][2]
Where to use it
- Suggested for interactive creative tools that need rapid image drafts or edits.[2]
- Worth evaluating for unified generation and multi-reference editing workflows such as design, logo, and image-edit iteration.[1][2]
- Suitable to prototype locally or deploy where open weights, consumer-GPU use, and Diffusers or ComfyUI support are priorities.[2]
Sources
- [1] OpenRouter catalog · Black Forest Labs: FLUX.2 Klein 4BSources checked: Nov 13, 2026
- [2] Model documentation · Black Forest Labs: FLUX.2 Klein 4BSources checked: Nov 13, 2026
About this model
Description below is the original text supplied by OpenRouter, shown in the source language.
FLUX.2 [klein] 4B is the fastest and most cost-effective model in the FLUX.2 family, optimized for high-throughput use cases while maintaining excellent image quality. Pricing is based on the output...
Specifications
- Model ID
- black-forest-labs/flux.2-klein-4b
- Creator
- black-forest-labs
- Added to OpenRouter
- 14.01.2026
- Context length
- 40,960
- Modality
- text+image->image
- Input modalities
- text, image
- Output modalities
- image
- Token pricing
- No per-token price in the source snapshot — see OpenRouter for the billing unit
- Knowledge cutoff
- —
- Expiration date
- —
Tasks and capabilities
A grade appears only where the source supplies a matching measurement for that task, the model is active and the cohort holds at least 10 comparable models. The capability column lists facts the source declares — supported formats, reasoning and tool parameters — which are not measured quality.
| Task | Grade | Source-declared capability |
|---|---|---|
| General quality | No measurement | — |
| Coding | No measurement | — |
| Agents | No measurement | — |
| Writing | No measurement | — |
| Reasoning | No measurement | — |
| Document analysis | No measurement | — |
| Vision | No measurement | input: image |
| Image generation | No measurement | output: image |
| Audio | No measurement | — |
| Video | No measurement | — |
| Embeddings | No measurement | — |
Evaluations
| Source | Benchmark | Value | Grade | Data retrieved |
|---|---|---|---|---|
| Design Arena | models · graphicdesignwin rate 35.7% · rank 12 | 1,004Elo | CC — below the B band | 13.11.2026 |
| Design Arena | models · imagewin rate 38.6% · rank 12 | 1,045Elo | CC — below the B band | 13.11.2026 |
| Design Arena | models · logowin rate 38% · rank 12 | 1,060Elo | CC — below the B band | 13.11.2026 |
| Design Arena | models · imageeditingwin rate 38.3% · rank 8 | 1,031Elo | —Not rated | 13.11.2026 |
How grades work
Each letter grade compares a model only against other models scored by the same source and metric in the current snapshot. S means the top 10%, A the next 20%, B the next 30%, C the rest. Models without a published measurement are shown as not rated — a supported format alone never implies measured quality.
- S — S — top 10% of the cohort
- A — A — next 20% of the cohort
- B — B — next 30% of the cohort
- C — C — below the B band
Providers
Optional live provider statistics from OpenRouter. Missing values are unknown, not zero.
| Provider | Context length | Price in /1M | Price out /1M | Latency p50 (30m, s) | Throughput p50 (30m, tok/s) | Uptime (30m) |
|---|---|---|---|---|---|---|
| Black Forest Labs | 40,960 | — | — | — | — | — |
Provider data retrieved: 13.11.2026
Related articles
No published articles identify this model yet.