Can the RTX 4090 24 GB run LTX-2.5 (22B)?
Not at full quality. The 16-bit and 8-bit files are too big for the RTX 4090 24 GB; the largest that fits is Q6_K (18.7 GB).
Q6_K (18.7 GB) fits with only 0.5 GB to spare (about 23.5 GB of 24 GB). Quality: very close to the original.
01What to download
| Part | File | Folder | Size | |
|---|---|---|---|---|
| Model | LTX-2.5-Distilled-Q6_K.gguf Q6_K · realrebelai/LTX-2.5_GGUFs | models/unet | 18.7 GB | Download → |
| Text encoder | gemma4-12b-with-proj-ltx-2.5-comfy-int8-convrot.safetensors Gemma 4 12B + LTX projection INT8 (convrot) · Lightricks/LTX-2.5 | models/text_encoders | 15.4 GB | Download → |
| VAE | ltx-2.5-video-vae-bf16.safetensors LTX-2.5 video VAE (DiffVAE) BF16 · Lightricks/LTX-2.5 | models/vae | 1.5 GB | Download → |
| Also needed | ltx-2.5-audio-vae-bf16.safetensors LTX-2.5 audio VAE + vocoder BF16 · Lightricks/LTX-2.5 | models/vae | 0.4 GB | Download → |
| Total download · keep about the same free on disk | 35.9 GB | |||
Alternatives: Gemma 4 12B + LTX projection BF16 (26.3 GB). Only for some workflows: LTX-2.5 latent spatial upscaler x2 (1.0 GB, official two-stage template); Gemma 4 E2B INT8 (prompt enhancer, optional) (5.2 GB, only if prompt enhancer enabled). Sizes from Hugging Face, 2026-10-01.
System RAM: 48 GB or more. These files take about 35.9 GB of RAM while loaded, 41.9 GB with Windows and ComfyUI. What happens with less. calculated
02Every LTX-2.5 file on 24 GB
| File | Size | Needed | On this card | Quality | Download |
|---|---|---|---|---|---|
| 16-bit SAFETENSORS · Lightricks | 42.0 GB | 46.8 GB | 22.8 GB too big | the original weights | Hugging Face → |
| Q8_0 GGUF · realrebelai | 23.6 GB | 28.4 GB | 4.4 GB too big | practically identical to the original | Hugging Face → |
| Q6_K ← GGUF · realrebelai | 18.7 GB | 23.5 GB | fits · 0.5 GB spare | very close to the original | Hugging Face → |
| Q5_K_M GGUF · realrebelai | 16.8 GB | 21.6 GB | fits · 2.4 GB spare | close; small differences in fine detail | Hugging Face → |
| Q4_K_M GGUF · realrebelai | 15.1 GB | 19.9 GB | fits · 4.1 GB spare | good; some loss in fine detail and text | Hugging Face → |
| Q3_K_M GGUF · realrebelai | 11.5 GB | 16.3 GB | fits · 7.7 GB spare | noticeable loss of detail | Hugging Face → |
| Q2_K GGUF · realrebelai | 8.8 GB | 13.6 GB | fits · 10.4 GB spare | heavy loss; a last resort | Hugging Face → |
“Needed” adds 4 GB of working memory for LTX-2.5 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 LTX-2.5 on a RTX 4090 24 GB, send your time per image and peak VRAM and it will appear here, credited.
04With more VRAM
With 32 GB you could run LTX-2.5 at 8-bit or better (Q8_0, 23.6 GB) with no offloading: for example on the RTX 5090 32 GB.
What changes from the RTX 4090 24 GB to the RTX 5090 32 GB →
05About the RTX 4090 24 GB
The RTX 4090 24 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.)
24 GB GDDR6X · 384-bit · 1008 GB/s · Ada Lovelace. Everything that runs on it →
06Questions
How much VRAM does LTX-2.5 need?
Around 13.6 GB with the smallest file (Q2_K) and 28.4 GB with an 8-bit file (Q8_0). The full 16-bit file needs about 46.8 GB.
Which LTX-2.5 file should I download for the RTX 4090 24 GB?
Q6_K (18.7 GB) from realrebelai/LTX-2.5_GGUFs. Load it with Unet Loader (GGUF) from the ComfyUI-GGUF node pack.
How much do I need to download for LTX-2.5 on the RTX 4090 24 GB?
35.9 GB: LTX-2.5-Distilled-Q6_K.gguf, gemma4-12b-with-proj-ltx-2.5-comfy-int8-convrot.safetensors, ltx-2.5-video-vae-bf16.safetensors, ltx-2.5-audio-vae-bf16.safetensors.