FLUX 2 Klein (BudgetPixel)

Klein is the answer BFL shipped to the complaint everyone had about FLUX 2: it's too heavy. The "klein" line is size-distilled FLUX - the version that reopened the consumer front when it landed as open weights in January 2026. On BudgetPixel's shelf it's the value pick: 10 credits per generation, sub-second server-side, and the same excellent prompt adherence that made FLUX 2 famous, with editing from up to three reference images.

At a tenth of the price of the 4K monsters in this pack, Klein is the node you use when you're iterating - exploring a prompt across a grid of seeds, testing composition ideas, doing a draft pass before committing to an expensive model. It's the sketchpad tier. The practical trade: it's not the quality ceiling, so for a final hero image you'd still reach for FLUX 2 Pro or GPT-Image-2. But for volume, 10 credits changes the math on "let me try ten variations."

How it works

Identical plumbing to the rest of the pack: POST /images/flux-2-klein with your prompt and optional references, poll /images/{id}, download the IMAGE batch. The distinguishing wrinkle is resolution: where other models take an aspect ratio, Klein takes megapixel-based resolution - you tell it how many megapixels you want rather than a fixed crop, which is FLUX 2's flexible-output style and a genuinely useful knob.

The inputs that matter

• prompt - required, multiline.
• megapixel - the resolution control; pick the target megapixel count and the model handles the geometry.
• aspect_ratio - still available if you want to force a shape.
• reference_images - up to 3 for image editing and composition.
• num_images - 1–4, default 1.
• seed - default -1 (random). Seeds are your best friend in the draft phase: keep one, tweak the prompt, compare.

Output is images (IMAGE batch).

Install

ComfyUI Manager (search "BudgetPixel") or:

cd ComfyUI/custom_nodes
git clone https://github.com/budgetpixel-ai/comfyui-budgetpixel.git
pip install -r comfyui-budgetpixel/requirements.txt

Restart, set BUDGETPIXEL_API_KEY or a budgetpixel.json ({"api_key": "bpx_live_..."}) in the pack folder. No weights to download; requests is the only dependency.

Where people get burned

The trap with cheap nodes is scale. Because each call is only 10 credits, it's easy to fire off a hundred drafts and find you've spent more than one careful 4K run would have - which is fine if that's the plan, and a surprise if it wasn't. Klein is also the wrong tool when you need precise multi-reference identity: it accepts up to three references, but the bigger, pricier FLUX 2 Dev (four refs, better reasoning) is the one for "this exact person in this exact outfit." Use Klein to find the idea, then pay for the render. And don't forget the pack-wide force_rerun toggle when you want to re-roll instead of getting a cached result.