What problem does it solve?
GPTQ solves the problem of deploying large LLMs with limited GPU memory and high inference cost by converting FP16/FP32 model weights into 4-bit weights while keeping accuracy degradation low.
Core Features & Use Cases
- 4-bit post-training quantization: Compress LLMs (e.g., 70B+ / 405B class) using group-wise quantization with minimal quality loss.
- Calibration-driven quality: Uses a small calibration set to minimize quantization error via Hessian-aware procedures.
- Backend-focused inference acceleration: Supports multiple execution backends (ExLlamaV2, Marlin, Triton) to improve tokens/sec.
- Workflow fit for research and deployment: Covers end-to-end quantization, saving/pushing models, and integration paths for inference and QLoRA-style fine-tuning.
Use it when you need to run a large model on consumer or single-GPU setups (e.g., RTX 4090/3090) with roughly 4× memory reduction and under ~2% perplexity degradation, or when you want significantly faster generation than FP16.
Quick Start
Run GPTQ quantization for your model by telling your AI to quantize meta-llama/Llama-2-7b-chat-hf to 4-bit using group_size 128 and calibrate on C4 for 128 samples, then save the resulting artifacts locally.