Can the Mac 48 GB run FLUX.1 Fill [dev]?
Yes. 16-bit fits on the Mac 48 GB with 13.8 GB to spare.
16-bit (23.8 GB) needs about 26.4 GB in use, so 13.8 GB of the 40.2 GB stays free: room for a larger image, a LoRA or a ControlNet.
01What to download
| Part | File | Folder | Size | |
|---|---|---|---|---|
| Model | flux1-fill-dev.safetensors 16-bit · black-forest-labs/FLUX.1-Fill-dev | models/diffusion_models | 23.8 GB | Download → |
| Text encoder | t5-v1_1-xxl-encoder-Q8_0.gguf T5-XXL GGUF Q8_0 · city96/t5-v1_1-xxl-encoder-gguf | models/text_encoders | 5.1 GB | Download → |
| Text encoder | clip_l.safetensors CLIP-L · comfyanonymous/flux_text_encoders | models/text_encoders | 0.2 GB | Download → |
| VAE | ae.safetensors FLUX.1 VAE (ae) · Comfy-Org/Lumina_Image_2.0_Repackaged | models/vae | 0.3 GB | Download → |
| Total download · keep about the same free on disk | 29.4 GB | |||
Alternatives: T5-XXL FP16 (9.8 GB). On a Mac, FP8 text encoders do not load, so a 16-bit one is listed - or a GGUF one, loaded with “CLIPLoader (GGUF)” from the ComfyUI-GGUF nodes. Sizes from Hugging Face, 2026-10-01.
Shared memory: about 35.4 GB of your 48 GB. On this machine the model, the text encoder, the VAE and the operating system all use the same memory. That leaves room, so nothing has to be swapped to disk. calculated
02Every FLUX.1 Fill file on 40.2 GB
| File | Size | Needed | On this card | Quality | Download |
|---|---|---|---|---|---|
| 16-bit ← SAFETENSORS · black-forest-labs | 23.8 GB | 26.4 GB | fits · 13.8 GB spare | the original weights | Hugging Face → |
| Q8_0 GGUF · YarvixPA | 12.7 GB | 15.3 GB | fits · 24.9 GB spare | practically identical to the original | Hugging Face → |
| Q6_K GGUF · YarvixPA | 9.9 GB | 12.5 GB | fits · 27.7 GB spare | very close to the original | Hugging Face → |
| Q5_K_S GGUF · YarvixPA | 8.3 GB | 10.9 GB | fits · 29.3 GB spare | close; small differences in fine detail | Hugging Face → |
| Q4_K_S GGUF · YarvixPA | 6.8 GB | 9.4 GB | fits · 30.8 GB spare | good; some loss in fine detail and text | Hugging Face → |
| Q3_K_S GGUF · YarvixPA | 5.2 GB | 7.8 GB | fits · 32.4 GB spare | noticeable loss of detail | Hugging Face → |
“Needed” adds 1.8 GB of working memory for FLUX.1 Fill and a 0.8 GB reserve. Sizes 2026-10-01.
03Measured and reported results
Nobody has sent measured numbers for this pair yet. If you run FLUX.1 Fill on a Mac 48 GB, send your time per image and peak VRAM and it will appear here, credited.
04About the Mac 48 GB
A Mac with 48 GB shares that memory between the CPU and the GPU. On current macOS the GPU may use about 40.2 GB of it by default (older macOS versions: about 38.7 GB); that is the figure used here. ComfyUI can go past it, but macOS then starts compressing and swapping memory and everything slows down. ComfyUI runs on Apple GPUs through PyTorch's MPS backend. 16-bit and GGUF files work; FP8 and INT8 files do not save memory on a Mac, so they are skipped. Speed is the catch: even the fastest Macs are several times slower per image than a desktop RTX card. Chips sold with 48 GB: M3 Max, M4 Pro, M4 Max, M5 Pro, M5 Max (memory bandwidth 273–614 GB/s - the higher, the faster). Everything about Macs and local AI →
48 GB unified · ~40.2 GB for the GPU · 273–614 GB/s · Apple Silicon. Everything that runs on it →
05Questions
How much VRAM does FLUX.1 Fill need?
Around 7.8 GB with the smallest file (Q3_K_S) and 15.3 GB with an 8-bit file (Q8_0). The full 16-bit file needs about 26.4 GB.
Which FLUX.1 Fill file should I download for the Mac 48 GB?
16-bit (23.8 GB) from black-forest-labs/FLUX.1-Fill-dev.
How much do I need to download for FLUX.1 Fill on the Mac 48 GB?
29.4 GB: flux1-fill-dev.safetensors, t5-v1_1-xxl-encoder-Q8_0.gguf, clip_l.safetensors, ae.safetensors.