Model reference · open weights

FLUX.1-Kontext-dev

Image black-forest-labs Image edit 4 builds Non-commercial 238k dl/mo

FLUX.1-Kontext-dev is an open-weight image model from Black Forest Labs. FLUX.1-Kontext-dev-GGUF (GGUF) weighs 6.9 GB; the smallest configuration that runs it is RTX 4060 Ti 16 GB.

  • FLUX.1-Kontext-dev is an image-to-image model developed by Black Forest Labs that uses a 11.9B parameter rectified flow transformer to edit images based on text instructions.
  • It supports English and allows for character, style, and object reference without finetuning.
  • The model is released under a non-commercial license.

Summary of the black-forest-labs/FLUX.1-Kontext-dev model card, 2026-10-01. The estimate below is for another build of the family.

What it is

Released byBlack Forest Labs
Released2025-05-28
Parameters11.9B
VRAM6.9 GB for the weights

What it runs on

Memory and cards for FLUX.1-Kontext-dev-GGUF (GGUF)

6.9 GBweights, file size
5.0 GBworking memory, one 1024² image
537 MBruntime overhead
CardOne imageMemory
RTX 3060 12 GBdoes not fit11.6 GB
RTX 4060 Ti 16 GBfits15.4 GB
RTX 3090 24 GBfits23.4 GB
RTX 4090 24 GBfits23.4 GB
RTX 5090 32 GBfits31.0 GB
L40S 48 GBfits44.0 GB
A100 80 GBfits78.2 GB
H100 80 GBfits78.1 GB
RTX PRO 6000 Blackwell 96 GBfits93.8 GB
DGX Spark (GB10) 128 GB unifiedfits107 GB
H200 141 GBfits138 GB
B200 180 GBfits176 GB

Builds

Sizes, precisions & builds

BuildParamsPrecisionWeightsSmallest setup
FLUX.1-Kontext-dev ↗ 11.9BBF16 33.7 GBRTX 5090 32 GB
FLUX.1-Kontext-dev-NVFP4 ↗
the transformer alone, to use with the text encoders and VAE
—NVFP4 9.2 GBRTX 4060 Ti 16 GB
FLUX.1-Kontext-dev-GGUF (above) ↗
packaged by unsloth
15 builds: Q2_K 4.0 GB … F16 23.8 GB
the transformer alone, to use with the text encoders and VAE
—GGUF 6.9 GBRTX 4060 Ti 16 GB
FLUX.1-Kontext-dev ↗
packaged by unsloth
11.9BBF16 33.7 GBRTX 5090 32 GB

From the model card

What Black Forest Labs says about FLUX.1-Kontext-dev

Read the model card

GGUF files for black-forest-labs/FLUX.1-Kontext-dev. Original license still applies.

A huge thanks to @doublemathew and @hrsvrn for help with conversion. GGUFs were created with city96/ComfyUI-GGUF and llama.cpp.

To run, use ComfyUI-GGUF and place the model files in the ComfyUI/models/unet directory. For more instructions, go to the README.

FLUX.1 Kontext [dev] is a 12 billion parameter rectified flow transformer capable of editing images based on text instructions. For more information, please read our blog post and our technical report. You can find information about the [pro] version in here.

Key Features

  1. Change existing images based on an edit instruction.
  2. Have character, style and object reference without any finetuning.
  3. Robust consistency allows users to refine an image through multiple successive edits with minimal visual drift.
  4. Trained using guidance distillation, making FLUX.1 Kontext [dev] more efficient.
  5. Open weights to drive new scientific research, and empower artists to develop innovative workflows.
  6. Generated outputs can be used for personal, scientific, and commercial purposes, as described in the FLUX.1 [dev] Non-Commercial License.

Usage

We provide a reference implementation of FLUX.1 Kontext [dev], as well as sampling code, in a dedicated github repository. Developers and creatives looking to build on top of FLUX.1 Kontext [dev] are encouraged to use this as a starting point. FLUX.1 Kontext [dev] is also available in both ComfyUI and Diffusers.

Using with diffusers 🧨

# Install diffusers from the main branch until future stable release
pip install git+https://github.com/huggingface/diffusers.git

Image editing:

import torch
from diffusers import FluxKontextPipeline
from diffusers.utils import load_image
pipe = FluxKontextPipeline.from_pretrained("black-forest-labs/FLUX.1-Kontext-dev", torch_dtype=torch.bfloat16)
pipe.to("cuda")
input_image = load_image("https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/diffusers/cat.png")
image = pipe(
  image=input_image,
  prompt="Add a hat to the cat",
  guidance_scale=2.5
).images[0]

Flux Kontext comes with an integrity checker, which should be run after the image generation step. To run the safety checker, install the official repository from black-forest-labs/flux and add the following code:

import torch
import numpy as np
from flux.content_filters import PixtralContentFilter
integrity_checker = PixtralContentFilter(torch.device("cuda"))
image_ = np.array(image) / 255.0
image_ = 2 * image_ - 1
image_ = torch.from_numpy(image_).to("cuda", dtype=torch.float32).unsqueeze(0).permute(0, 3, 1, 2)
if integrity_checker.test_image(image_):
raise ValueError("Your image has been flagged. Choose another prompt/image or try again.")

For VRAM saving measures and speed ups check out the diffusers docs


Risks

Black Forest Labs is committed to the responsible development of generative AI technology. Prior to releasing FLUX.1 Kontext, we evaluated and mitigated a number of risks in our models and services, including the generation of unlawful content. We implemented a series of pre-release mitigations to help prevent misuse by third parties, with additional post-release mitigations to help address residual risks:

  1. Pre-training mitigation. We filtered pre-training data for multiple categories of “not safe for work” (NSFW) content to help prevent a user generating unlawful content in response to text prompts or uploaded images.
  2. Post-training mitigation. We have partnered with the Internet Watch Foundation, an independent nonprofit organization dedicated to preventing online abuse, to filter known child sexual abuse material (CSAM) from post-training data. Subsequently, we undertook multiple rounds of targeted fine-tuning to provide additional mitigation against potential abuse. By inhibiting certain behaviors and concepts in the trained model, these techniques can help to prevent a user generating synthetic CSAM or nonconsensual intimate imagery (NCII) from a text prompt, or transforming an uploaded image into synthetic CSAM or NCII.
  3. Pre-release evaluation. Throughout this process, we conducted multiple internal and external third-party evaluations of model checkpoints to identify further opportunities for improvement. The third-party evaluations—which included 21 checkpoints of FLUX.1 Kontext [pro] and [dev]—focused on eliciting CSAM and NCII through adversarial testing with text-only prompts, as well as uploaded images with text prompts. Next, we conducted a final third-party evaluation of the proposed release checkpoints, focused on text-to-image and image-to-image CSAM and NCII generation. The final FLUX.1 Kontext [pro] (as offered through the FLUX API only) and FLUX.1 Kontext [dev] (released as an open-weight model) checkpoints demonstrated very high resilience against violative inputs, and FLUX.1 Kontext [dev] demonstrated higher resilience than other similar open-weight models across these risk categories. Based on these findings, we approved the release of the FLUX.1 Kontext [pro] model via API, and the release of the FLUX.1 Kontext [dev] model as openly-available weights under a non-commercial license to support third-party research and development.

Quoted from the model card on Hugging Face. The full card is behind the Hugging Face link above.

Running it yourself

Run it on a rented GPU

Rent a machine by the hour. ComfyUI is installed on it. Open ComfyUI through the tunnel, then Templates → Flux Kontext Dev Image Edit: it loads ComfyUI's own build of this model, the files above.

# on your rented machine (the ssh line is on its page in the console)
# get REPO FILE FOLDER: one file into /workspace/models/FOLDER, where ComfyUI loads it from
get() { hf download "$1" "$2" --local-dir /workspace/hf-files && mkdir -p "/workspace/models/$3" && mv "/workspace/hf-files/$2" "/workspace/models/$3/$4"; }

# the files of the template “Flux Kontext Dev Image Edit” (16.4 GB)
get Comfy-Org/Lumina_Image_2.0_Repackaged split_files/vae/ae.safetensors vae
get comfyanonymous/flux_text_encoders clip_l.safetensors text_encoders
get comfyanonymous/flux_text_encoders t5xxl_fp8_e4m3fn_scaled.safetensors text_encoders
get Comfy-Org/flux1-kontext-dev_ComfyUI split_files/diffusion_models/flux1-dev-kontext_fp8_scaled.safetensors diffusion_models

start-comfyui
Renting a GPU: connect, tunnels, ComfyUI
# on your computer, in a second terminal: ComfyUI in your browser at http://localhost:8188
# HOST and PORT are your machine's, from its page in the console
ssh -L 8188:localhost:8188 dev@HOST -p PORT
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