Flux.2 Klein 9B
Frontierby Black Forest Labs
Mid-range 9B variant of FLUX.2 Klein family. Sub-second generation on H100. DiT architecture with T5-XXL + CLIP-L text encoders (4.82B combined). Higher quality than the 4B sibling while remaining efficient.
VRAM requirements, GPU fit, and setup notes for Flux.2 Klein 9B, including 8GB/12GB fit guidance where relevant. Recommended runtimes: ComfyUI and Diffusers support. Best download size: ~9.0 GB at FP8.
- 9B DiT — sub-second on H100
- Higher quality than Klein 4B
- T5-XXL + CLIP-L text encoders (4.82B)
- Non-commercial license
Your hardware
Detecting...
Image Quality Benchmarks
Measured quality metrics for Flux.2 Klein 9B outputs.
How often humans prefer this model's output (0-100%)
Visual quality and composition rating (5-9 scale)
VRAM Requirements by Resolution and Precision
Compare which GPUs can run Flux.2 Klein 9B at different precisions. FP8 uses less memory than FP16 when available, and the grade shows how comfortably each GPU handles the workload.
FP16 (full precision)
| Resolution | VRAM Required | RTX 4090 24GB | RTX 3060 12GB | RTX 4060 8GB | MacBook Pro M4 Pro 24GB |
|---|---|---|---|---|---|
| 512×512 | 28.5 GB | D● | F● | F● | F● |
| 768×768 | 28.7 GB | D● | F● | F● | F● |
| 1024×1024 | 29.0 GB | D● | F● | F● | F● |
FP8 (~40% less VRAM)
| Resolution | VRAM Required | RTX 4090 24GB | RTX 3060 12GB | RTX 4060 8GB | MacBook Pro M4 Pro 24GB |
|---|---|---|---|---|---|
| 512×512 | 13.6 GB | S● | B● | F● | S● |
| 768×768 | 13.8 GB | S● | D● | F● | S● |
| 1024×1024 | 14.0 GB | S● | D● | F● | A● |
Optimization Tips
Turbo / LCM distillation
Use distilled scheduler at 4-8 steps for faster iteration
Run with Python
from diffusers import FluxPipeline
import torch
pipe = FluxPipeline.from_pretrained(
"black-forest-labs/FLUX.2-klein-9B",
torch_dtype=torch.float16
)
pipe.to("cuda")
image = pipe(
prompt="your prompt here",
num_inference_steps=20,
guidance_scale=3.5,
height=1024,
width=1024,
).images[0]
image.save("output.png")Get started
Setup instructions for running Flux.2 Klein 9B locally
1. Download the model
Get the checkpoint from HuggingFace
2. Place in:
ComfyUI/models/checkpoints/3. Launch ComfyUI
python main.pyMemory Breakdown
VRAM allocation at 1024×1024 on RTX 4090 24GB (24 GB)
Estimated Generation Time
Time per image at 1024×1024, 28 steps, FP16.
Sample Outputs
Available Formats, Downloads & Setup
Download Flux.2 Klein 9B in the precision that matches your GPU. Lower precision usually means less VRAM pressure, while higher precision keeps more quality.
LoRA Ecosystem
LimitedLimited LoRA availability. Some FLUX.2 LoRAs may be compatible.
Related Workflows
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Frequently asked questions
FAQ — Flux.2 Klein 9B VRAM, Runtimes & Fit
How much VRAM does Flux.2 Klein 9B need?
Flux.2 Klein 9B (9B parameters) requires approximately 29.0 GB of VRAM at FP16 precision for standard 1024×1024 image generation. If you want a lighter setup, lower precisions like FP8 can reduce memory use when available.
Can I run Flux.2 Klein 9B on an 8GB GPU?
Flux.2 Klein 9B usually needs more than 8GB for comfortable local use. Check the VRAM table above for the exact resolution and precision trade-off.
Does Flux.2 Klein 9B work in ComfyUI and Diffusers?
Flux.2 Klein 9B is marked for ComfyUI and Diffusers support in our catalog, so those are the runtimes we recommend first for local setup. If your workflow uses another front end, check the model's available formats and workflow notes above before downloading.
Can I run Flux.2 Klein 9B on RTX 4090?
Flux.2 Klein 9B is too large for the RTX 4090's 24 GB VRAM at FP16. Consider using FP8 precision or a GPU with more VRAM.
Does Flux.2 Klein 9B support ControlNet?
There are currently no known ControlNet adapters for Flux.2 Klein 9B. Check Hugging Face and Civitai for community-contributed adapters.
Does Flux.2 Klein 9B have LoRA support?
Limited LoRA availability. Some FLUX.2 LoRAs may be compatible. The LoRA ecosystem for Flux.2 Klein 9B is rated as "minimal". Each LoRA adds roughly 0.2 GB of extra VRAM.
How fast is Flux.2 Klein 9B?
On a reference GPU (RTX 4090 24GB), Flux.2 Klein 9B generates a 1024×1024 image in approximately ~3.7s at FP16 with 28 inference steps. Faster GPUs with higher memory bandwidth will produce images more quickly.
About Flux.2 Klein 9B
See also