The identity parameters × bits / 8 is a storage sketch. For 8,000,000,000 parameters at 4 bits it is exactly 4,000,000,000 bytes. That test exists in this repo. It is not a promise that every “4-bit” file is 0.5 bytes per parameter.
Qwen2.5-7B-Instruct (7.61B parameters on the model card):
| Kind | Bytes | What it is |
|---|---|---|
BF16 safetensors total_size |
15,231,233,024 | Selected BF16 tensors |
| Official GGUF Q8_0 shards | 8,098,525,408 | Those three Q8_0 files only |
| Official GGUF Q4_K_M shards | 4,683,073,632 | Those two Q4_K_M files only |
| Theoretical INT4 | 7.61e9 × 4 / 8 ≈ 3.805e9 | Sketch, no metadata |
Q4_K_M is not 4.000 bits. Block scales and non-quantized tensors make the file larger than the theoretical INT4 line. AWQ/GPTQ names are not used as 0.5 bytes/parameter without file metadata.
Calculator 0.1.0, dataset 2026-09-19.1. Context and KV are extra in every row.