"Parameters × bits ÷ 8" is the rule everyone quotes for how much GPU memory a model needs. It gets you in the right neighbourhood and then lets you down exactly where it matters: on the card that is 2 GB too small, or on the 32k-token chat that suddenly no longer fits. So I stopped estimating and pulled the numbers from the source for 35 current open models: Weights : the real size of the published file — GGUF builds by unsloth, ggml-org, bartowski and the model authors (Q4_K_M unless ...