Stable Diffusion 3 Medium Gets Official GGUF Support

Stable Diffusion 3 Medium is now available in GGUF format, bringing the same quantization benefits that revolutionized LLM inference to image generation. The collaboration between Stability AI and the llama.cpp community has produced quantized variants that slash VRAM requirements while maintaining strong image quality.

VRAM savings

The original SD3 Medium checkpoint requires approximately 8GB of VRAM for inference at 1024x1024 resolution. The Q5_K GGUF quantization reduces this to about 5GB, while Q4_K brings it down to approximately 3.8GB. This means budget GPUs like the RTX 4060 with 8GB can now generate SD3 images comfortably, and even the GTX 1660 Super with 6GB can handle the Q4 variant.

Image quality comparison

In our testing, the Q5_K quantization produces images virtually indistinguishable from the full-precision model. Q4_K shows very slight softening in fine details like text rendering and intricate patterns, but for general use the quality difference is negligible. The Q8 variant is perceptually identical to the original for all practical purposes.

How to use it

The GGUF SD3 Medium files work with stable-diffusion.cpp, which follows the same paradigm as llama.cpp. ComfyUI also supports the format through the GGUF loader nodes. For the simplest setup, download the Q5_K file from Hugging Face and point your preferred UI at it.

Broader implications

GGUF quantization for diffusion models is a relatively new development but an important one. Image generation has traditionally been less memory-efficient than text generation because the models operate on continuous latent spaces rather than discrete tokens. The success of SD3 Medium GGUF paves the way for quantized versions of larger image models like FLUX and future architectures.