ComfyUI Flux.2 Klein 4B Guide

A quick introduction to FLUX.2 [klein] 4B and how to run text-to-image and image editing workflows in ComfyUI.

About FLUX.2 [klein]

FLUX.2 [Klein] is the fastest model in the Flux family, unifying text-to-image and image editing in one compact architecture. It’s designed for interactive workflows, immediate previews, and latency-critical applications, with distilled variants delivering end-to-end inference around one second while keeping strong quality for single- and multi-reference editing.

Model highlights:

• Two 4B types: Base (undistilled) for maximum flexibility and fine-tuning; Distilled (4-step) for speed-first deployments
• Performance: distilled ~1.2s (5090) · 8.4GB VRAM; base ~17s (5090) · 9.2GB VRAM
• Editing support: style transforms, semantic edits, object replacement/removal, multi-reference composition, iterative edits

Portable or self deployed users

Make sure your ComfyUI is updated.

• Download ComfyUI
• Update Guide

Workflows in this guide can be found in the Workflow Templates. If you can’t find them in the template, your ComfyUI may be outdated. (Desktop version’s update will delay sometime)

If nodes are missing when loading a workflow, possible reasons:

1. You are not using the latest ComfyUI version (Nightly version)
2. Some nodes failed to import at startup

Desktop or Cloud users

• The Desktop is base on ComfyUI stable release, it will auto-update when there is a new Desktop stable release available.
• Cloud will update after ComfyUI stable release.

So, if you find any core node missing in this document, it might be because the new core nodes have not yet been released in the latest stable version. Please wait for the next stable release.

Flux.2 Klein 4B Workflows

4B Text-to-Image Workflow

Download the text-to-image workflow for Flux.2 Klein 4B.

4B Image Edit Base

Download the image editing workflow using the 4B base model.

4B Image Edit Distilled

Download the fast distilled 4B image editing workflow.

Flux.2 Klein 4B Model Downloads

qwen_3_4b.safetensors

Text encoder for 4B models.

flux-2-klein-base-4b-fp8.safetensors

Diffusion model (4B base).

flux-2-klein-4b-fp8.safetensors

Diffusion model (4B distilled).

flux2-vae.safetensors

VAE for 4B models.

4B Model Storage Location

📂 ComfyUI/
├── 📂 models/
│   ├── 📂 text_encoders/
│   │      └── qwen_3_4b.safetensors
│   ├── 📂 diffusion_models/
│   │      ├── flux-2-klein-base-4b-fp8.safetensors
│   │      └── flux-2-klein-4b-fp8.safetensors
│   └── 📂 vae/
│          └── flux2-vae.safetensors

Flux.2 Klein 9B Workflows

9B Text-to-Image Workflow

Download the text-to-image workflow for Flux.2 Klein 9B.

9B Image Edit Base

Download the image editing workflow using the 9B base model.

9B Image Edit Distilled

Download the fast distilled 9B image editing workflow.

Flux.2 Klein 9B Model Downloads

For diffusion models, please visit BFL’s repo, accept the agreement, and then download the models.

flux-2-klein-base-9b-fp8.safetensors

Diffusion model (9B base).

flux-2-klein-9b-fp8.safetensors

Diffusion model (9B distilled).

qwen_3_8b_fp8mixed.safetensors

Text encoder for 9B models.

flux2-vae.safetensors

VAE for 9B models.

9B Model Storage Location

📂 ComfyUI/
├── 📂 models/
│   ├── 📂 diffusion_models/
│   │      ├── flux-2-klein-9b-fp8.safetensors
│   │      └── flux-2-klein-base-9b-fp8.safetensors
│   ├── 📂 text_encoders/
│   │      └── qwen_3_8b_fp8mixed.safetensors
│   └── 📂 vae/
│          └── flux2-vae.safetensors