LTX-2 (19B) on 12 GB of VRAM
Not entirely. Even Q2_K is 0.9 GB over 12 GB, so ComfyUI keeps part of it in system RAM. Lightricks' open audio+video model. Generates sound together with the picture. Its text encoder is Gemma 3 12B.
Nothing fits entirely, but Q2_K (8.1 GB) overflows by only about 0.9 GB. ComfyUI keeps that part in system RAM automatically: slower than a full fit, but usable.
01Other amounts of VRAM
02Every file, on 12 GB
| File | Size | Needed | On this card | Quality | Download |
|---|---|---|---|---|---|
| 16-bit GGUF · unsloth | 37.8 GB | 42.6 GB | 30.6 GB too big | the original weights | Hugging Face → |
| Q8_0 GGUF · unsloth | 20.4 GB | 25.2 GB | 13.2 GB too big | practically identical to the original | Hugging Face → |
| Q6_K GGUF · unsloth | 16.0 GB | 20.8 GB | 8.8 GB too big | very close to the original | Hugging Face → |
| Q5_K_M GGUF · unsloth | 14.3 GB | 19.1 GB | 7.1 GB too big | close; small differences in fine detail | Hugging Face → |
| Q4_K_M GGUF · unsloth | 12.8 GB | 17.6 GB | 5.6 GB too big | good; some loss in fine detail and text | Hugging Face → |
| Q3_K_M GGUF · unsloth | 10.1 GB | 14.9 GB | 2.9 GB too big | noticeable loss of detail | Hugging Face → |
| Q2_K ← GGUF · unsloth | 8.1 GB | 12.9 GB | spills 0.9 GB | heavy loss; a last resort | Hugging Face → |
“Needed” adds 4 GB of working memory for LTX-2 and a 0.8 GB reserve. Sizes 2026-10-01.
03What to download
| Part | File | Folder | Size | |
|---|---|---|---|---|
| Model | ltx-2-19b-dev-Q2_K.gguf Q2_K · unsloth/LTX-2-GGUF | models/unet | 8.1 GB | Download → |
| Text encoder | gemma_3_12B_it_fp8_scaled.safetensors Gemma 3 12B FP8 (scaled) · Comfy-Org/ltx-2 | models/text_encoders | 13.2 GB | Download → |
| VAE | ltx-2-19b-dev_video_vae.safetensors LTX-2 video VAE · unsloth/LTX-2-GGUF | models/vae | 2.4 GB | Download → |
| Also needed | ltx-2-19b-dev_audio_vae.safetensors LTX-2 audio VAE · unsloth/LTX-2-GGUF | models/vae | 0.2 GB | Download → |
| Also needed | ltx-2-19b-dev_embeddings_connectors.safetensors LTX-2 text embeddings connectors (projection) · unsloth/LTX-2-GGUF | models/text_encoders | 2.9 GB | Download → |
| Total download · keep about the same free on disk | 26.8 GB | |||
Alternatives: Gemma 3 12B FP4 mixed (9.4 GB); Gemma 3 12B BF16 (24.4 GB). FP4 files are listed only as alternatives unless the GPU is an RTX 50 (Blackwell). Only for some workflows: LTX-2 spatial upscaler x2 (1.0 GB, official two-stage template). Sizes from Hugging Face, 2026-10-01.
System RAM: 48 GB or more. These files take about 26.8 GB of RAM while loaded, 32.8 GB with Windows and ComfyUI. What happens with less. calculated
04The text encoder
Take the smallest Gemma 3 12B file (9.4 GB): it is the only one that fits in 12 GB on its own. Sizes: 16-bit 24.4 GB, FP8 13.2 GB, FP4 mixed 9.4 GB. Why the encoder does not count against VRAM →