Welcome FLUX.3 Image Klein in Diffusers

Black Forest Labs FLUX.3 Image Klein is here, and it runs in Diffusers from day one. One model does text-to-image and multi-reference image-to-image, and it adds something new, the layout control. You write bounding boxes into the prompt to say where each part of the image should go, or which parts of a reference image to move.

Both open checkpoints are in the FLUX.3 Image Klein collection:

Checkpoint	What it is	Defaults
black-forest-labs/flux-3-image-klein	Time step distilled, for fast inference	16 steps, no CFG
black-forest-labs/flux-3-image-klein-base	Base model	50 steps, CFG

You can head on to the Hugging Face space and generate some images right now!

TL;DR

• One model for text-to-image, multi-reference image-to-image, and bounding-box layout control.
• The distilled checkpoint makes a 1024 × 1024 image in about 2 seconds on an H100.
• NVFP4 and FP8 weights load with from_single_file, for smaller GPUs.
• LoRA training scripts for both text-to-image and image editing.
• Ships as a Modular Diffusers pipeline, so you can pop blocks out or add your own.

Contents

• Getting started
• What FLUX.3 can do
• Base model and quantized variants
• LoRA finetuning
• What it costs to run
• The architecture
• Modular Diffusers
• Try it

Getting started

Install the latest diffusers and transformers (for the Qwen3-VL text encoder):

pip install -U diffusers transformers

Load the distilled checkpoint and generate an image:

import torch
from diffusers import ModularPipeline

pipe = ModularPipeline.from_pretrained("black-forest-labs/flux-3-image-klein")
pipe.load_components(dtype=torch.bfloat16)
pipe.to("cuda")

pipe(prompt="a red fox", output="images")[0].save("fox.png")

What FLUX.3 can do

Text-to-image

Text to image

Image-to-image

Pass a reference image (or more) with the image argument. Write the prompt as a caption of the image you want, with the change included.

Image to image

With several references, refer to them in the prompt as <ref_image_0>, <ref_image_1>, ... in the order they are passed to image: