image model · stable-diffusion · macOS
SD Can I run Stable Diffusion 1.5 on Apple M3 Ultra (256GB)?
Yes. Stable Diffusion 1.5 runs on Apple M3 Ultra (256GB) at fp16 (~3.7 GB of ~192 GB usable).
Runs at fp16 using ~3.7 GB of ~192 GB usable.
- Peak VRAM
- ~3.7 GB
- Usable on device
- ~192 GB
- Device memory
- 256 GB
- Quant
- fp16
How to run it
Use AUTOMATIC1111 or ComfyUI at fp16. It conditions on an image, not a text prompt; the pipeline offloads each stage off the GPU between passes, keeping peak VRAM near the active stage.
- Type
- image (UNET)
- Parameters
- 860M
- Peak VRAM
- ~3.7 GB at fp16
- Resolution
- 512×512
- License
- CreativeML OpenRAIL-M
- Memory
- 256 GB unified
- Usable for weights
- ~192 GB
- Best runtime
- MLX direct / Ollama (MLX backend)
You could also run
Run Stable Diffusion 1.5 on other hardware
FAQ
Can Apple M3 Ultra (256GB) run Stable Diffusion 1.5?
Yes. Stable Diffusion 1.5 runs on Apple M3 Ultra (256GB) at fp16 (~3.7 GB of ~192 GB usable).
How much VRAM does Stable Diffusion 1.5 need?
Apple M3 Ultra (256GB) has room to spare. At fp16 the realistic peak is ~3.7 GB of VRAM, versus ~4 GB with every component kept resident (no offload). With aggressive CPU offload it drops to ~2 GB, much slower.
What do I use to run Stable Diffusion 1.5 locally?
Stable Diffusion 1.5 runs in AUTOMATIC1111 or ComfyUI (among others). It loads as a diffusion checkpoint plus its image encoder and VAE, not a single chat command.
Sources
VRAM figures are sourced peak-usage anchors at the noted quant, validated 2026-06-15. See methodology.