Can the RTX 4050 Laptop 6 GB run Z-Image (base)?
Nothing fits entirely, but Q5_K_M (5.6 GB) overflows by only about 1.6 GB. ComfyUI keeps that part in system RAM automatically: slower than a full fit, but usable.
Worth trying on this GPU: with an up-to-date ComfyUI, Dynamic VRAM (on by default for NVIDIA since March 2026) streams whatever does not fit from system RAM, and ComfyUI's own start-up message recommends native FP8/INT8 files over GGUF, saying they “will be faster even if they are larger than your memory”. So before settling for a heavily compressed GGUF, try the native INT8 file (6.2 GB). The file recommended above is the best one that fits entirely — the safe choice on older ComfyUI versions, AMD and Intel. Comfy blog: Dynamic VRAM →
01What to download
| Part | File | Folder | Size | |
|---|---|---|---|---|
| Model | z-image-Q5_K_M.gguf Q5_K_M · unsloth/Z-Image-GGUF | models/unet | 5.6 GB | Download → |
| Text encoder | qwen_3_4b_fp8_mixed.safetensors Qwen3 4B FP8 · Comfy-Org/z_image | models/text_encoders | 5.6 GB | Download → |
| VAE | ae.safetensors FLUX.1 VAE (ae) · Comfy-Org/z_image | models/vae | 0.3 GB | Download → |
| Total download · keep about the same free on disk | 11.5 GB | |||
Alternatives: Qwen3 4B BF16 (8.0 GB). The 16-bit text encoder is a little more faithful; the smaller one is chosen here because it loads faster and needs less RAM. Sizes read from Hugging Face (2026-09-25). “Download” links start the file directly; the file name links are the same files the official ComfyUI workflows use.
System RAM: 32 GB or more. ComfyUI keeps the model file, the text encoder and the VAE in system RAM and moves them to the GPU as needed. With this set of files that is about 11.5 GB, plus roughly 6 GB for Windows, ComfyUI and a browser: 17.5 GB in total. With less RAM it still runs, but Windows starts swapping to disk and loading gets very slow. calculated
02Every Z-Image file on 6 GB
| File | Size | Needed | On this card | Quality | Download |
|---|---|---|---|---|---|
| 16-bit SAFETENSORS · Comfy-Org | 12.3 GB | 14.3 GB | 8.3 GB too big | the original weights | Hugging Face → |
| Q8_0 GGUF · unsloth | 7.2 GB | 9.2 GB | 3.2 GB too big | practically identical to the original | Hugging Face → |
| INT8 SAFETENSORS · Comfy-Org | 6.2 GB | 8.2 GB | 2.2 GB too big | practically identical to the original | Hugging Face → |
| Q6_K GGUF · unsloth | 6.1 GB | 8.1 GB | 2.1 GB too big | very close to the original | Hugging Face → |
| Q5_K_M ← GGUF · unsloth | 5.6 GB | 7.6 GB | spills 1.6 GB | close; small differences in fine detail | Hugging Face → |
| Q4_K_M GGUF · unsloth | 5.1 GB | 7.1 GB | spills 1.1 GB | good; some loss in fine detail and text | Hugging Face → |
| Q3_K_M GGUF · unsloth | 4.6 GB | 6.6 GB | spills 0.6 GB | noticeable loss of detail | Hugging Face → |
| Q2_K GGUF · unsloth | 4.0 GB | 6.0 GB | spills 0.0 GB | heavy loss; a last resort | Hugging Face → |
Sizes from the Hugging Face file listing, read 2026-09-25. “Needed” = file + 1.2 GB working memory for this model + 0.8 GB kept free for the system.
03The text encoder
Qwen3 4B: 8.0 GB as 16-bit, 5.6 GB as FP8. ComfyUI encodes the prompt first and can push the encoder out of VRAM before sampling, so it does not have to fit together with the model. On 6 GB the encoder itself is too big for VRAM, so let it run from system RAM: slower prompt encoding, same images.
04About this GPU
The RTX 4050 Laptop 6 GB is an Ada Lovelace GPU with hardware FP8, so ComfyUI can compute Comfy-Org's FP8 files natively: small and fast. (Plain FP8 files use FP8 maths with the --fast fp8_matrix_mult option.) As a laptop GPU it runs at a lower power limit than desktop cards (35–115 W depending on the laptop). The memory verdicts are the same; speed depends heavily on how much power the laptop maker allows.
RTX 4050 Laptop 6 GB: 6 GB GDDR6 · 96-bit · Ada Lovelace · 35–115 W. Everything that runs on the RTX 4050 Laptop 6 GB →
05What more VRAM would change
With 10 GB you could run Z-Image at 8-bit or better (Q8_0, 7.2 GB) with no offloading: for example on the RTX 3080 10 GB.
06Measured and reported results
Nobody has sent measured numbers for this pair yet. If you run Z-Image on a RTX 4050 Laptop 6 GB, send your time per image and peak VRAM and it will appear here, credited.
07Questions
How much VRAM does Z-Image need?
Around 6.0 GB with the smallest file (Q2_K) and 8.2 GB with an 8-bit file (INT8), counting working memory and a small system reserve. The full 16-bit file needs about 14.3 GB.
Which Z-Image file should I download for the RTX 4050 Laptop 6 GB?
Q5_K_M (5.6 GB) from unsloth/Z-Image-GGUF. Load it with Unet Loader (GGUF) from the ComfyUI-GGUF node pack.
Is FP8 faster than GGUF on the RTX 4050 Laptop 6 GB?
It can be. This GPU has FP8 hardware, and ComfyUI computes FP8 natively for files made for it (Comfy-Org's fp8_scaled files), or for any FP8 file with the --fast fp8_matrix_mult option. GGUF files are unpacked on the fly, which costs some speed.
How much do I need to download for Z-Image on the RTX 4050 Laptop 6 GB?
About 11.5 GB for the model file, text encoder and VAE listed on this page, and the same again free on disk. With a 6 GB card, 32 GB of system RAM or more is recommended.