Comparison
FLUX 3 Klein vs FLUX 2 Klein
FLUX 3 Klein is the new small open-weight model in the FLUX 3 family; FLUX.2 Klein 9B is the previous generation. They do not answer the same question, and the cost of switching is not the same for every job. Below you can see both models on the same six prompts, compare the published specifications, and decide which one fits the work in front of you.
This box opens the generator with FLUX 3 Klein — the only model this site runs. Run a prompt here, then compare it with the pairs below.
The same six prompts on both models
Every image below was generated on this site: FLUX 3 Image Klein (distilled) and FLUX.2 Klein 9B (distilled), one output each, the same prompt, the same 1:1 frame, the same 1K tier. The last pair is a multi-reference edit — both models received the same two reference images and the same instruction. Read the notes as what these particular outputs show, not as a general verdict.
Product photo · FLUX 3 Klein
Studio product photograph of a matte terracotta ceramic bowl on a pale oak table, soft morning window light from the left, a folded linen napkin and three walnuts beside it, clean warm-white background, 50mm lens, realistic glaze texture.
Product photo · FLUX.2 Klein 9B
The FLUX.2 output fills the frame with the bowl and drops the table edge; the FLUX 3 output keeps the table edge, the window light and the napkin in shot.
Poster with text · FLUX 3 Klein
Minimal Swiss-style concert poster with the headline "LOW TIDE" in bold condensed black sans-serif across the top, the date "NOV 08" in red below it, a single deep-blue circle overlapping a thin grid, off-white paper texture, small credits text at the bottom, printed risograph look.
Poster with text · FLUX.2 Klein 9B
Both render the headline and the date correctly. The FLUX 3 output is framed as printed paper photographed on a wall with a visible shadow; the FLUX.2 output is a flat full-bleed layout with a wider grid and less legible credits.
Portrait · FLUX 3 Klein
Editorial portrait of a man in his forties with short dark hair and a charcoal wool coat, standing in a rain-slicked city street at dusk, overcast light on his face, blurred taxi lights behind him, Kodak Portra film colour, 85mm lens.
Portrait · FLUX.2 Klein 9B
The FLUX 3 output is a tighter head-and-shoulders crop with a cooler, darker grade; the FLUX.2 output is a wider crop that keeps more of the wet street and the taxis in frame.
Flat illustration · FLUX 3 Klein
Flat vector illustration of a lighthouse on a rocky cliff at night, teal and coral palette, simple geometric waves, a single beam of light sweeping left, subtle paper grain, children's book illustration. The top third is empty navy sky. Image only, no text, no letters, no typography, no watermark.
Flat illustration · FLUX.2 Klein 9B
The FLUX 3 output leaves the top third as empty navy sky and keeps the paper grain; the FLUX.2 output fills that sky with the light beam and adds a wave band across the middle.
Busy interior · FLUX 3 Klein
Wide interior shot of a busy artisan bakery at opening time, wooden counter with trays of sourdough, a barista pulling a lever espresso machine, two customers waiting by the window, warm morning light through tall windows, dust in the air, architectural photography, straight verticals.
Busy interior · FLUX.2 Klein 9B
Both keep the counter, the trays and the customers. The FLUX 3 output puts one barista in the foreground with cooler concrete tones; the FLUX.2 output adds a second staff member and warmer pendant lighting.
Multi-reference edit · FLUX 3 Klein
Place the bottle from the first reference image on the counter in the second reference image, keep the light and the shadows unchanged, add a soft reflection under the bottle.
Multi-reference edit · FLUX.2 Klein 9B
Given the same two references and the same instruction, the FLUX 3 output places the exact amber bottle from the first reference — label included — on the counter from the second; the FLUX.2 output returns a different, clear bottle with different label text on a different surface.
Published specifications
Only rows with a public source are listed, and every figure comes from the vendor's own release notes or model card. Where a number is not published, the row is left out rather than estimated.
| FLUX 3 Klein | FLUX.2 Klein 9B | |
|---|---|---|
| Released | October 15, 2026 | January 15, 2026 |
| Parameters (image model) | 5.6B | 9B (and a 4B variant) |
| Text encoder | Qwen3-VL-4B-Instruct | 8B Qwen3 text embedder |
| Open-weight licence | FLUX Kommunity License — non-commercial, plus commercial output for users under US$5M annual revenue | FLUX Non-Commercial License for 9B; Apache 2.0 for 4B |
| Multi-reference editing | Yes — up to 10 reference images | Yes — multi-reference generation |
| Distilled generation | 16 steps, no guidance | 4 inference steps |
| Undistilled base checkpoint | Yes — 50 steps, guidance 3.5 | Yes — 4B and 9B |
Sources: bfl.ai/blog/flux-3-image-klein, huggingface.co/black-forest-labs/flux-3-image-klein-base, bfl.ai/blog/flux2-klein-towards-interactive-visual-intelligence and huggingface.co/black-forest-labs/FLUX.2-klein-9B, all read on October 17, 2026. Neither vendor publishes a maximum output resolution for FLUX.2 Klein 9B, so no resolution row is shown.
What actually differs in daily use
Specifications are the easy part. These are the differences that show up when you are the one typing the prompt.
Reference handling
FLUX 3 Klein takes up to ten reference images and can be told where an item belongs, including bounding boxes on a 0–1000 grid. FLUX.2 Klein 9B also works from several references, but the multi-reference pair above shows the practical gap: on the same instruction, one output kept the referenced object and its printed label, the other returned a different object.
Prompt length
Both models were trained on full scene captions, and both vendors warn that short prompts give generic output. Black Forest Labs ships a prompt upsampler with FLUX 3 Klein for exactly this reason. Write two or three sentences about framing, light and materials and you will get more out of either model.
Text inside the image
Both put short headlines, dates and labels into the picture. In the poster pair above, both rendered the headline and the date correctly; the smaller credits text degraded in both and stayed more readable in the FLUX 3 output. Check the spelling before you publish anything.
Licence and self-hosting
The two open-weight releases do not carry the same licence. FLUX.2 Klein 4B is Apache 2.0, the 9B variants are non-commercial, and FLUX 3 Klein ships under the FLUX Kommunity License, which allows commercial output for individuals and companies under US$5M in annual revenue. Read the licence text before you build a product on either.
Which one to reach for
Neither model wins everything. Match the task to the model instead of the model to the trend.
Product shots and packaging
If the product has to survive the edit — same bottle, same label, same proportions — use FLUX 3 Klein with a reference image and describe what must stay unchanged. FLUX.2 Klein 9B is fine when you are generating the product from scratch.
Text-heavy graphics
Posters, covers and banners with a short headline: both models work, and both need you to check the small type. Keep the words in quotes and keep them few.
Fast drafts
FLUX.2 Klein 9B was built for sub-second iteration and is the lighter download for local experiments. When you are exploring twenty directions, that speed is the feature.
Combining several photos
The more references a job needs, the more the ten-reference ceiling and the placement syntax of FLUX 3 Klein matter. This is where the two generations separate most clearly.
Editing an existing photo
Both accept an instruction plus an image. Write the instruction as a full description of the finished picture, and say explicitly what must not change.
What this site supports today
This site runs FLUX 3 Klein, and only FLUX 3 Klein. Here is exactly what the online generator does, so the comparison above is not mistaken for a feature list.
One model, one workspace
Text-to-image and editing are the same model here. There is no FLUX.2 Klein tab and no model switcher.
Up to three reference images
The generator accepts one to three attached images, and you can address them as <ref_image_1> to <ref_image_3> in the prompt.
1K and 2K output
Fifteen aspect ratios from 1:1 to 21:9, saved as JPEG, PNG or WebP.
Not supported here
Ten reference images, bounding boxes, 4K output, LoRA training and weight downloads are not part of this site. The open weights and the reference code are published by Black Forest Labs on Hugging Face and GitHub.
Credits per generation
Text-to-image costs 2 credits at 1K and 8 at 2K. Editing costs 4, 5 or 6 credits at 1K with one, two or three references, and 13, 15 or 17 at 2K.
Ten languages
The generator, this page and every help page are translated into English, Chinese, Russian, German, French, Japanese, Korean, Spanish, Portuguese and Turkish.
FLUX 3 Klein vs FLUX.2 Klein
Is FLUX 3 Klein better than FLUX.2 Klein?
Black Forest Labs' own comparison reports FLUX 3 Klein ahead by 91 Elo in text-to-image and 70 in image editing over FLUX.2 Klein 9B, with 38% fewer parameters. That is the vendor's internal evaluation, not an independent one. In the six pairs above you can see what changed for this particular prompt set; the honest answer for your own work is to run two or three of your own prompts through both.
Is FLUX.2 Klein free?
The 4B model is released under Apache 2.0, so it is free to use and modify under that licence. The 9B models, including the one compared on this page, are under the FLUX Non-Commercial License, which does not permit commercial use. Neither licence says anything about what a hosted service may charge you to run the model.
Which FLUX model is the best?
It depends on the job, not on the family name. FLUX 3 Image is the flagship image model of the FLUX 3 generation; FLUX 3 Image Klein is its small open-weight sibling and the only model on this site; FLUX.2 Klein 9B is the previous small generation. For work that combines several references or needs placement control, the newer Klein is the stronger choice; for sub-second local drafting, the older 9B is still quick.
Try the newer Klein on your own prompt
Write one full sentence about the image you want, run it here, and compare it with the pairs above.