What Quantization Costs You in Quality (August 2026)
How much quality a smaller quant actually loses. Real MMLU and KL Divergence numbers across Q2_K through Q8_0, plus how to measure on your own workload.
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How much quality a smaller quant actually loses. Real MMLU and KL Divergence numbers across Q2_K through Q8_0, plus how to measure on your own workload.
The published GGUF file size is the weights. VRAM use also includes the KV cache, framework overhead, and your context length. The math, walked through.
Five stock GGUF quants for Qwen3.8-27B span 9.01 GB to 29.05 GB. A file size is not a VRAM requirement, and a 262,144-token ceiling is not free to fill.
8-bit measures close to lossless. 4-bit ranges from a 0.6% gain to a 59% drop on one benchmark, depending on the model. The figures, fully attributed.
Quantization formats compared with real file sizes and bits per weight. Why Q4 does not halve a model, and why low quants generate faster.
Two back-to-back merges add MiniMax Sparse Attention and a Qwen2.5-VL style vision tower to llama.cpp, but every existing MiniMax-M3 GGUF must be regenerated.