---
id: "2026-10-15-flux-3-image-klein-open-weights"
url: "https://postcutoff.com/e/2026-10-15-flux-3-image-klein-open-weights/"
as_of: "2026-10-16T12:39:00+02:00"
date: "2026-10-15"
date_precision: day
category: media-generation
importance: 3
confidence: high
status: [Confirmed]
sources: 4
editor: human editor
human_review: null
version: "2026-10-16"
---

As of: 2026-10-16 12:39 CEST.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/e/2026-10-15-flux-3-image-klein-open-weights/

# FLUX 3 Image Klein (5.6B open weights)

Full title: Black Forest Labs releases FLUX 3 Image Klein, a 5.6B open-weights image generation and editing model

On Oct 15, 2026 Black Forest Labs released FLUX 3 Image Klein, a 5.6B-parameter open-weights model for text-to-image, image editing and multi-reference generation (up to 10 reference images) with native 4K output and bounding-box control. BFL's own Elo tests put it first among open-weights image models and above closed Ideogram V4.5 and FLUX.2 [pro]. Weights are under the FLUX Kommunity License (free commercial use under $5M annual revenue); the API price is $0.009 per 1K image.

## Key facts
- Size: 5.6B image transformer (text encoder Qwen3-VL-4B-Instruct, Apache-2.0, separate); base checkpoint (50 steps, guidance 3.5) for fine-tuning and a step-distilled checkpoint (16 steps, no guidance) for low latency; FP8, INT8 and NVFP4 builds
- Capabilities shared with FLUX 3 Image: native 4K generation, bounding boxes (0–1000 grid) to place, move, recolor, replace or remove elements; one model for text-to-image, single-reference editing and up to 10 reference images
- BFL's internal Elo: first among open-weights models in text-to-image, multi-reference and editing; above closed Ideogram V4.5 and FLUX.2 [pro]; vs FLUX.2 [klein] 9B +91 Elo (text-to-image) and +70 (editing) with 38% fewer parameters; compared with Qwen-Image 2.1 (7B) and Krea 2 (12.9B)
- Speed (BFL): API median 4.54 s (text-to-image) and 7.18 s (editing) at 1 MP incl. queueing; locally ~4 s per 1 MP on an RTX 5090 and under 9 s on an RTX 4070 (distilled, INT8, ComfyUI); under 0.6 s on a GB300 with NVFP4; INT8 build runs on 8 GB VRAM
- Model card: 'Do not use the model without a prompt upsampler' (flux-3-image-klein-pup, a 9B model); peak memory on a B200 at 1024² without upsampler 31 GB (BF16) / 26 GB (FP8) / 25 GB (NVFP4)
- Licence: FLUX Kommunity License v1.0: commercial output generation for users under US$5M gross annualized revenue; otherwise a commercial licence from BFL; Hugging Face access gated (contact details)
- API: flux-3-image-klein on the BFL API; per-image price $0.008 (768²), $0.009 (1K), $0.011 (1.5K), $0.014 (2K), $0.036 (4K), same for generation and editing

## What happened

Black Forest Labs (BFL) published FLUX 3 Image Klein on Oct 15, 2026 (the Hugging Face repository was created on Oct 13
and was trending on Oct 16). It is the small, open-weights member of the FLUX 3 family announced in July. The 5.6B model
handles text-to-image, editing and multi-reference generation in one network and keeps two features of the larger FLUX 3
Image: native 4K output and bounding boxes that steer where elements go (they guide placement but are not hard masks).

BFL ships a base checkpoint for fine-tuning and LoRA training and a step-distilled one for fast generation, plus FP8, INT8
and NVFP4 builds. The model card insists on a separate 9B prompt upsampler, because short prompts give generic results. The
blog says the INT8 build runs on GPUs with 8 GB of VRAM; the card's B200 memory table (25–31 GB without the upsampler)
measures a different setup, so local requirements depend on the build and the pipeline.

All quality and speed numbers are BFL's own (internal Elo evaluations; API latency measured end to end, other models timed
from the client, so BFL itself says the comparison is not like for like).

## Why it matters

It brings FLUX 3-class editing and 4K output to consumer GPUs a day after Krea 3 and a month after Qwen-Image 2.1, and it
uses the same "free under $5M revenue" licence pattern that open image models increasingly adopt instead of Apache-2.0
(FLUX.2 [klein] 4B was Apache-2.0).

## Your AI and this story

- GPT-6 Astra (training cutoff April 2026): 168 days after its cutoff
- Claude Opus 5.5 (training cutoff June 2026): 107 days after its cutoff
- Gemini 4 Argon (training cutoff March 2026): 198 days after its cutoff
- Grok 4.7 (training cutoff May 2026): 137 days after its cutoff

## Sources

1. [Black Forest Labs: FLUX 3 Image Klein (blog)](https://bfl.ai/blog/flux-3-image-klein) (bfl.ai, official)
2. [Hugging Face: black-forest-labs/flux-3-image-klein (model card)](https://huggingface.co/black-forest-labs/flux-3-image-klein) (huggingface.co, code)
3. [BFL API pricing](https://docs.bfl.ai/quick_start/pricing) (docs.bfl.ai, docs)
4. [GitHub: reference code](https://github.com/black-forest-labs/flux-3-image-klein) (github.com, code)

## Changes

- 2026-10-16 (filed): Created (found through Hugging Face trending)

## Related

- 2026-10-15: [Krea 3 image-editing model (open beta)](https://postcutoff.com/e/2026-10-15-krea-3-image-editing-model/index.md)
- 2026-09-20: [Alibaba releases Qwen-Image-2.1, a 7B open-weights image generation and editing model with native transparency](https://postcutoff.com/e/2026-09-20-qwen-image-2-1/index.md)
- 2026-07-23: [Black Forest Labs unveils FLUX 3](https://postcutoff.com/e/2026-07-23-black-forest-labs-flux-3/index.md)
- Models: [FLUX 3 Image Klein](https://postcutoff.com/m/flux-3-image-klein/) (`flux-3-image-klein`)