FLUX.1-dev ConvRot for ComfyUI

Native ComfyUI ConvRot quantizations of FLUX.1-dev, with three diffusion-model choices and an optional INT8 ConvRot T5-XXL text encoder.

These are post-training quantized derivatives of black-forest-labs/FLUX.1-dev at source revision 3de623fc3c33e44ffbe2bad470d0f45bccf2eb21. They load with ComfyUI's core UNETLoader; no custom INT4 loader is required.

License: The model weights are subject to the upstream FLUX.1-dev Non-Commercial License. Access and use require compliance with that license and the upstream acceptable-use terms. See License before downloading.

Files and recommended combinations

File	Role	Size	Recommendation
`FLUX.1-dev-w8a8-convrot.safetensors`	Whole-DiT ConvRot W8A8	11.981 GB	Default DiT: best storage/fidelity balance
`FLUX.1-dev-int8_convrot.safetensors`	Partial ConvRot INT8 with sensitive tensors preserved	15.920 GB	Quality-first DiT: closest tested quantized variant to BF16
`FLUX.1-dev-paper-w4a4-convrot.safetensors`	Paper-aligned whole-DiT ConvRot W4A4	6.248 GB	Memory-first / experimental
`t5xxl_flux1_int8_convrot.safetensors`	Experimental T5-XXL ConvRot W8A8	4.898 GB	Optional text-encoder companion

The four uploadable files total 39.047 GB. The Original BF16 model shown in the comparison is a reference and is not included.

Recommended pipelines:

Lowest combined storage: FLUX.1-dev-w8a8-convrot.safetensors + t5xxl_flux1_int8_convrot.safetensors.
Default quality/storage balance: FLUX.1-dev-w8a8-convrot.safetensors + upstream BF16 T5-XXL.
Quality-first: FLUX.1-dev-int8_convrot.safetensors + upstream BF16 T5-XXL.
Memory-first: FLUX.1-dev-paper-w4a4-convrot.safetensors + upstream BF16 T5-XXL.

The optional INT8 T5 does not contain CLIP-L. FLUX still requires CLIP-L and a VAE.

What W8A8 and W4A4 mean

ConvRot stores rotated quantized weights plus per-layer metadata. At runtime, the quantized weight layout dispatches the matching ComfyUI/comfy-kitchen linear operator. The current BF16 activation is rotated and dynamically quantized for the matrix multiplication; activations are not stored in the checkpoint.

W8A8: INT8 weights and dynamically quantized INT8 activations for selected linear layers.
W4A4: packed INT4 weights and dynamically quantized INT4 activations for selected linear layers.
Biases, norms, embeddings, and tensors outside each policy remain at their declared higher precision.

Rotation group size is 256. The W4A4 artifact uses quantization group size 64.

ComfyUI installation

Place the selected files as follows:

ComfyUI/models/diffusion_models/FLUX.1-dev-w8a8-convrot.safetensors
# or FLUX.1-dev-int8_convrot.safetensors
# or FLUX.1-dev-paper-w4a4-convrot.safetensors

ComfyUI/models/text_encoders/t5xxl_flux1_int8_convrot.safetensors  # optional

You must separately obtain the standard FLUX assets under their applicable licenses:

ComfyUI/models/text_encoders/clip_l_flux1.safetensors
ComfyUI/models/text_encoders/t5xxl_flux1_bf16.safetensors  # unless using the INT8 T5 here
ComfyUI/models/vae/ae_flux1.safetensors

Use a current ComfyUI and comfy-kitchen build with native ConvRot support. The validated environment was:

ComfyUI 0.28.0
comfy-kitchen 0.2.20
comfy-cli 1.11.1
NVIDIA CUDA GPU

W4A4 requires SM 8.0 or newer. The first run may compile kernels and take longer.

Load the diffusion model with core UNETLoader and weight_dtype=default. Load CLIP-L and the chosen T5 with DualCLIPLoader(type=flux).

A ready-to-use API/comfy-cli workflow is provided at workflows/FLUX1_Dev_ConvRot_API.json. It defaults to Whole W8A8 + INT8 T5. Change the diffusion-model and/or T5 filename to test another combination.

A maintained copy is available in the general comfy-workflows repository for direct API use.

Paired quality evaluation

Twenty 1024×1024 images were generated per pipeline with identical prompts, seeds, sampler, scheduler, guidance, steps, CLIP-L, and VAE. Metrics compare final 8-bit RGB images to Original BF16.

Pipeline	Global PSNR vs BF16	Mean per-pair PSNR	Low-VRAM maximum peak
Whole W8A8 + INT8 T5	26.559 dB	28.872 dB	16,265 MiB
Whole W8A8 + BF16 T5	27.399 dB	29.449 dB	16,298 MiB
Partial INT8 + BF16 T5	27.888 dB	29.857 dB	20,351 MiB
Paper W4A4 + BF16 T5	17.926 dB	19.041 dB	10,797 MiB

The isolated T5 comparison—same Whole W8A8 DiT, BF16 T5 versus INT8 T5—measured 27.389 dB global PSNR and 30.054 dB mean per-pair PSNR.

PSNR measures paired pixel similarity, not aesthetics, prompt adherence, anatomy, typography, or human preference. Small spatial changes can sharply reduce PSNR. LPIPS and human-preference metrics were not computed.

Full records:

VRAM methodology

Each benchmark cell used a fresh ComfyUI process. Total physical GPU memory was sampled every 20 ms under an exclusive GPU lock. Settings were 1024×1024, batch 1, 20 steps, Euler/simple, CFG 1.0, FLUX guidance 3.5. --lowvram is an offloading result; hardware, runtime versions, attention backend, and workflow can materially change memory use.

The no-offloading --highvram maximum peaks for the four publication pipelines were 19,998 MiB, 21,342 MiB, 21,342 MiB, and 18,974 MiB in the table's order. Original BF16 hit a capacity failure in that 24 GiB environment.

Quantization policies

Whole W8A8: all 304 paper-scoped 2-D transformer-block linear weights use tensorwise INT8 ConvRot; 476 tensors remain BF16 or otherwise preserved.
Partial INT8: profile-based selective INT8 ConvRot with a larger BF16-preserved set. This is the largest and highest-PSNR tested quantized DiT.
Paper W4A4: 301 paper-scoped transformer-block linears use W4A4; 479 tensors remain BF16 or otherwise preserved. ComfyUI's fused single_blocks.*.linear1 expands some paper component-level decisions to the fused tensor.
INT8 T5-XXL: 168 encoder linear projections use W8A8; 51 embedding, relative-attention-bias, and normalization tensors remain BF16. This T5 policy is experimental and was not evaluated by the ConvRot paper.

See manifests/conversion_summaries.json and release_manifest.json for artifact-level provenance and hashes.

Limitations

These are post-training quantizations, not fine-tuned models.
The W4A4 result diverges substantially more from BF16 and is labeled experimental.
INT8 T5 image similarity does not establish long-prompt comprehension equivalence.
Results cover 20 fixed prompts and one validated runtime/hardware environment.
No safety classifier or content filter is included.
Quantized checkpoints do not remove the limitations or usage restrictions of FLUX.1-dev.

License

The quantized weights are derivatives of FLUX.1-dev and are provided under the FLUX.1-dev Non-Commercial License. Review and comply with the exact upstream license:

The helper workflow/scripts do not grant additional rights to the model weights. See LICENSE_NOTICE.md.

Credits

Base model: Black Forest Labs, FLUX.1-dev
Quantized runtime: ComfyUI and comfy-kitchen
Conversion tooling: Starnodes Model Converter
Method reference: ConvRot: Rotation-Based Plug-and-Play 4-bit Quantization for Diffusion Transformers, arXiv:2512.03673

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Paper for SearchingMan/FLUX.1-dev-ConvRot

ConvRot: Rotation-Based Plug-and-Play 4-bit Quantization for Diffusion Transformers

Paper • 2512.03673 • Published Dec 3, 2025