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Glossary · ComfyUI Basics

What Is VRAM in ComfyUI?

By Earngenix Team ·

⚡ Quick Answer

VRAM is the memory built directly onto your graphics card. ComfyUI loads the model weights, the text encoder, the VAE, and the image or video data being generated into this memory while it works. Run out of it, and generation either crashes or slows down drastically as data spills over to system RAM.

It's separate from your computer's regular system RAM. A machine can have 64 GB of system RAM and still fail to generate an image if the GPU only has 6 GB of VRAM, because the model has to sit on the GPU itself to run efficiently.

Where You'll See It

VRAM doesn't have its own node — it shows up as a limit. Your terminal window prints a CUDA out of memory error when a workflow asks for more than your card has. Model download pages state a required amount (for example, "16 GB VRAM") next to the checkpoint, which tells you what that specific file needs at its native precision.

Quick Example

The full fp16 version of FLUX.1-dev needs roughly 24 GB of VRAM to load comfortably. A quantized GGUF version of the same model, at a lower precision, can run the identical workflow on an 8 GB card — at a small cost to output quality.

Video models generally need far more VRAM than image models at the same resolution, because they hold multiple frames in memory at once instead of a single image.

Frequently Asked Questions

8 GB covers most fp8 and GGUF-quantized image models at moderate resolutions. 12-16 GB gives you comfortable headroom for SDXL/Flux-class checkpoints and LoRAs. Video models (Wan, LTX, HunyuanVideo) generally want 16 GB or more for anything past a few seconds of footage.

ComfyUI either crashes the generation with a CUDA out-of-memory error in the terminal, or silently falls back to offloading parts of the model to system RAM, which is dramatically slower. Lowering resolution, batch size, or switching to a smaller/quantized model version fixes both.

Not directly — VRAM is a capacity limit, not a speed limit. Extra VRAM lets you run larger models, higher resolutions, or bigger batches without crashing, but a card with less VRAM and a faster core can still generate a single image quicker if the model fits.

See It In Action

Want to know exactly what your GPU can run?

Our VRAM & Hardware Guide breaks down which models and resolutions fit which card.

Published: 2026-09-17 · Last updated: 2026-09-17

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