FLUX.1 Kontext [dev] on 20 GB of VRAM
Yes. Q8_0 fits on 20 GB with 4.7 GB to spare. The image-editing member of the FLUX.1 family: give it a picture and an instruction, it changes only what you asked for.
Runs well
Yes.
Take Q8_0 (12.7 GB). In use it comes to about 15.3 GB, with 4.7 GB left over on 20 GB.
Best fileQ8_0
File size12.7 GB
VRAM needed~15.3 GB
System RAM32 GB+
Memory map · 20 GB GPU15.3 GB / 20 GB
010 GB20 GB
Weights Q8_0 · 12.7 GBWorking memory · 1.8 GBReserve · 0.8 GBFree · 4.7 GB
calculated How this is counted.
Got an RTX 40 or 50? Swap Q8_0 for FP8 (11.9 GB): same quality class, computed natively there.
01What to download
| Part | File | Folder | Size | |
|---|---|---|---|---|
| Model | flux1-kontext-dev-Q8_0.gguf Q8_0 · QuantStack/FLUX.1-Kontext-dev-GGUF | models/unet | 12.7 GB | Download → |
| Text encoder | t5xxl_fp8_e4m3fn.safetensors T5-XXL FP8 · comfyanonymous/flux_text_encoders | models/text_encoders | 4.9 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 | 18.2 GB | |||
Alternatives: T5-XXL FP16 (9.8 GB). Sizes from Hugging Face, 2026-10-01.
Free ComfyUI workflow, tested on my RTX 5060 Ti: FP8 workflow (.json) · GGUF Q8_0 workflow (.json). Drag the file into ComfyUI. All workflows →
02Every file, on 20 GB
| File | Size | Needed | On this card | Quality | Download |
|---|---|---|---|---|---|
| 16-bit SAFETENSORS · black-forest-labs | 23.8 GB | 26.4 GB | 6.4 GB too big | the original weights | Hugging Face → |
| Q8_0 ← GGUF · QuantStack | 12.7 GB | 15.3 GB | fits · 4.7 GB spare | practically identical to the original | Hugging Face → |
| FP8 SAFETENSORS · Comfy-Org | 11.9 GB | 14.5 GB | fits · 5.5 GB spare | practically identical to the original | Hugging Face → |
| Q6_K GGUF · QuantStack | 9.8 GB | 12.4 GB | fits · 7.6 GB spare | very close to the original | Hugging Face → |
| Q5_K_M GGUF · QuantStack | 8.4 GB | 11.0 GB | fits · 9.0 GB spare | close; small differences in fine detail | Hugging Face → |
| Q4_K_M GGUF · QuantStack | 6.9 GB | 9.5 GB | fits · 10.5 GB spare | good; some loss in fine detail and text | Hugging Face → |
| Q3_K_M GGUF · QuantStack | 5.4 GB | 8.0 GB | fits · 12.0 GB spare | noticeable loss of detail | Hugging Face → |
| Q2_K GGUF · QuantStack | 4.0 GB | 6.6 GB | fits · 13.4 GB spare | heavy loss; a last resort | Hugging Face → |
“Needed” adds 1.8 GB of working memory for FLUX.1 Kontext and a 0.8 GB reserve. Sizes 2026-10-01.