Guides
GGUF quantization explained
GGUF is the file format llama.cpp uses, and the letters after a model name tell you how much precision was thrown away to make it smaller. Q4_K_M, Q5_K_M, Q8_0 and the rest are not brand names: they describe a quantisation method and a target size. This guide explains what the labels mean, what the trade-off is, and how to pick one that fits your machine. It is not a benchmark. The numbers below come from llama.cpp's own quantisation documentation, which lists bits per weight and file sizes for Llama 3.1 8B. They were checked on 29 October 2026. Your model and your tasks may behave differently. What quantisation does A model is a large set of weights, normally stored at 16-bit or 32-bit precision. Quantisation stores those weights with fewer bits: 8, 6, 5, 4, 3 or even 2. The file gets smaller and usually needs less memory, which is how a model that would not fit on your GPU can suddenly run on it. The cost is accuracy. llama.cpp's documentation says quantisation ...