LLM Quantization Trade-Off Calculator

Compare VRAM requirements and quality trade-offs between quantization levels. Find the cheapest GPU that runs your model at your chosen precision.

Quantization Calculator
Model
Precision
VRAM at FP16
39.1 GB
VRAM at Q4_K_M
9.8 GB
VRAM saved
29.3 GB (75%)
Throughput boost
3.0×
Estimated quality delta (Q4_K_M vs FP16):
  • MMLU: −2.50 points
  • HumanEval: −3.50 points
  • Acceptable, ~5–7% quality drop
GPU cost savings: Cheapest GPU for FP16: L40S 48GB ($913/mo) → Q4_K_M: RTX 3090 ($255/mo). Monthly savings: $657Rent RTX 3090

Quality estimates from published research (approximate). Always eval on your task. GPU prices verified 2026-08-19. · LLM RAM Calculator

How to Use

Choose your model

Select the open-weight model you want to quantize. VRAM requirements are calculated from parameter count.

Set baseline and target

Select your current precision (baseline) and the quantization level you're considering. FP16 is the standard baseline.

Review the trade-off

The calculator shows VRAM saved, approximate quality loss on MMLU and HumanEval benchmarks, and throughput improvement.

See GPU cost savings

Find the cheapest GPU that fits each quantization level and the monthly cost difference.

Understanding quantization quality loss

Benchmark numbers are approximations based on published research. Real-world quality loss depends heavily on your specific task — classification is nearly unaffected at Q4, while complex code generation degrades measurably. Always run your task-specific evals before committing to a lower quantization level in production.

How to Cut This Cost

Up to 75%

Drop from FP16 to Q4_K_M — VRAM halves and throughput roughly doubles. Quality loss on most practical tasks is under 3%.

Up to 60%

Use a smaller model at FP16 rather than a large model at Q3. Llama 3.3 70B Q4 usually outperforms Llama 3.1 405B at Q3 on coherence.

Up to 50%

Use spot GPU instances — running a quantized model on a spot RTX 4090 ($0.74/hr) is often cheaper than on-demand A10G at FP16.

FAQ

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Last verified: 2026-08-20 · methodology · data sources