LLM Quantization & Multi-GPU VRAM Calculator
Precision hardware sizing for AI engineers across the US & UK. Estimate GGUF, EXL2, AWQ, and FP16 memory footprints, KV cache overhead, and real-world tokens/sec across 30+ GPUs.
ollama run llama3.1:8b
1. Model & Hardware Configuration
2. Hardware Compatibility & Speed Telemetry
Evaluating an 8.03B Parameter LLM against 1x NVIDIA RTX 4090 (24 GB VRAM).
3. Complete Quantization Formats Breakdown (GGUF, EXL2, AWQ, FP16)
| Format & Engine | Bitrate | Weights | KV Cache | Total VRAM | Est. Speed | Quality / Perplexity | Hardware Status |
|---|---|---|---|---|---|---|---|
|
FP16 / BF16
Full Precision • Original Weights
|
16.00 bpw | 16.06 GB | 1.00 GB | 18.56 GB | ~45.2 tok/s | Lossless 100% (+0.000 (Baseline)) | Fits in VRAM (100% GPU) |
|
FP8 / Q8_0
GGUF / vLLM • Production Grade
|
8.50 bpw | 8.53 GB | 1.00 GB | 11.03 GB | ~85.1 tok/s | 99.9% Near-Lossless (+0.004) | Fits in VRAM (100% GPU) |
|
Q6_K (6-bit)
GGUF k-quant • High Precision
|
6.56 bpw | 6.58 GB | 1.00 GB | 9.08 GB | ~110.2 tok/s | 99.5% Excellent (+0.021) | Fits in VRAM (100% GPU) |
|
Q5_K_M (5-bit)
GGUF k-quant • Balanced Plus
|
5.69 bpw | 5.71 GB | 1.00 GB | 8.21 GB | ~127.1 tok/s | 99.0% Very High (+0.056) | Fits in VRAM (100% GPU) |
|
Q4_K_M (4-bit)
GGUF k-quant • Recommended
|
4.85 bpw | 4.87 GB | 1.00 GB | 7.37 GB | ~149.1 tok/s | 98.2% Sweet Spot (+0.152) | Fits in VRAM (100% GPU) |
|
AWQ / GPTQ 4-bit
vLLM / TensorRT • High Throughput
|
4.50 bpw | 4.52 GB | 1.00 GB | 7.02 GB | ~160.7 tok/s | 98.0% Fast Serving (+0.160) | Fits in VRAM (100% GPU) |
|
EXL2 (4.0 bpw)
ExLlamaV2 • Max Speed
|
4.00 bpw | 4.01 GB | 1.00 GB | 6.51 GB | ~180.8 tok/s | 97.6% Ultra Fast (+0.195) | Fits in VRAM (100% GPU) |
|
IQ4_XS (i-Matrix)
GGUF i-quant • VRAM Saver
|
4.25 bpw | 4.27 GB | 1.00 GB | 6.77 GB | ~170.1 tok/s | 97.8% Compact 4-bit (+0.180) | Fits in VRAM (100% GPU) |
|
Q3_K_M (3-bit)
GGUF k-quant • Tight VRAM
|
3.91 bpw | 3.92 GB | 1.00 GB | 6.42 GB | ~184.9 tok/s | 94.5% Noticeable Loss (+0.480) | Fits in VRAM (100% GPU) |
|
IQ3_XXS (3-bit i-quant)
GGUF i-quant • Extreme Fit
|
3.06 bpw | 3.07 GB | 1.00 GB | 5.57 GB | ~236.3 tok/s | 92.0% Degraded (+0.710) | Fits in VRAM (100% GPU) |
|
Q2_K (2-bit)
GGUF k-quant • Last Resort
|
2.63 bpw | 2.64 GB | 1.00 GB | 5.14 GB | ~274.9 tok/s | 85.0% Experimental (+1.650) | Fits in VRAM (100% GPU) |
|
IQ1_S (1.58-bit)
GGUF Sub-2-bit • Ultra Extreme
|
1.56 bpw | 1.57 GB | 1.00 GB | 4.07 GB | ~350.0 tok/s | 72.0% Heavy Loss (+3.800) | Fits in VRAM (100% GPU) |
Multi-Vendor GPU & Accelerator Compatibility Cards
Live comparison across 31 consumer, workstation, Apple Unified Memory, and data-center GPUs for your active model configuration (shown for Q4_K_M 4-bit quantization). Click any card for its dedicated hardware benchmark page.
NVIDIA RTX 5080
NVIDIA RTX 5070 Ti
NVIDIA RTX 5070
NVIDIA RTX 4090
NVIDIA RTX 4080 Super
NVIDIA RTX 4070 Ti Super
NVIDIA RTX 4070 Super
NVIDIA RTX 4060 Ti 16GB
NVIDIA RTX 4060
NVIDIA RTX 3090 / 3090 Ti
NVIDIA RTX 3080 12GB
NVIDIA RTX 3060 12GB
Apple M3 Ultra (Mac Studio)
Apple M4 Max 128GB
Apple M4 Max 64GB
Apple M4 Pro 64GB (Mac mini)
Apple M4 24GB (Mac mini)
AMD Radeon RX 7900 XTX
AMD Radeon RX 7900 XT
AMD Radeon PRO W7900
AMD Instinct MI300X
NVIDIA RTX 6000 Ada
NVIDIA RTX A6000
NVIDIA L40S 48GB
NVIDIA A100 80GB SXM
NVIDIA H100 80GB SXM5
NVIDIA H200 141GB
NVIDIA DGX Spark (GB10)
Intel Arc A770 16GB
Intel Arc B580 12GB
Programmatic LLM Hardware & Quantization Directory
Explore pre-calculated VRAM profiles, GQA KV cache tables, and multi-GPU deployment guides for top open-weights LLMs. Our edge router supports any custom model URL pattern (e.g., /model/your-model-70b).
Meta Llama 3.3 70B Instruct
Meta Llama 3.3 70B Instruct delivers flagship 405B-class reasoning and coding performance in a dense 70.6-billion p...
Meta Llama 3.1 8B Instruct
Meta Llama 3.1 8B is the industry-standard edge LLM for consumer GPUs, capable of running at 100+ tokens/sec in Q4_...
Meta Llama 3.1 405B Instruct
Meta Llama 3.1 405B is one of the largest dense open-weights foundation models, requiring multi-GPU tensor parallel...
DeepSeek-R1 671B (MoE)
DeepSeek-R1 671B is a Mixture-of-Experts (MoE) reasoning model with 671B total parameters and 37B active parameters...
DeepSeek-R1 Distill Qwen 32B
DeepSeek-R1 Distill Qwen 32B packs frontier chain-of-thought math and coding capability into a 32.8B dense model th...
DeepSeek-R1 Distill Llama 70B
Distilled from DeepSeek-R1 onto the Llama 3.3 70B backbone, offering elite reasoning accuracy for dual-24GB GPU set...
Qwen 2.5 72B Instruct
Qwen 2.5 72B Instruct is a top-tier multilingual and coding foundation model with 80 transformer layers and 128K co...
Qwen 2.5 Coder 32B Instruct
Qwen 2.5 Coder 32B is the premier open-weights code generation and refactoring model designed to fit on a single 24...
Qwen 2.5 14B Instruct
Qwen 2.5 14B bridges the gap between 8B and 32B models, running effortlessly on 12GB and 16GB GPUs with room to spa...
Mistral Small 3 24B Instruct
Mistral Small 3 24B is engineered for low-latency local inference on 16GB and 24GB GPUs with only 40 layers for rap...
Mistral Large 2 123B
Mistral Large 2 123B is a flagship dense model ideal for 96GB+ Mac Studio configurations or dual-48GB workstation G...
Mixtral 8x7B Instruct (MoE)
Mixtral 8x7B uses a sparse Mixture-of-Experts architecture where 46.7B parameters reside in VRAM while only 12.9B a...
Mixtral 8x22B Instruct (MoE)
Mixtral 8x22B combines 141B total weights with a fast 39B active parameter path per token....
Google Gemma 3 27B Instruct
Google Gemma 3 27B delivers exceptional performance-per-watt on single 24GB GPUs such as the RTX 3090, RTX 4090, an...
Microsoft Phi-4 14B
Microsoft Phi-4 14B is trained on high-density synthetic textbook data, achieving STEM reasoning comparable to mode...
Cohere Command R+ 104B
Cohere Command R+ 104B specializes in Retrieval-Augmented Generation (RAG), citations, and multi-step tool use....
Popular Model + GPU Hardware Pairing Guides (US & UK Benchmarks)
Exact VRAM & KV Cache Engineering Formulas
Unlike rough rule-of-thumb estimators, quantizationcalculator.com models the exact memory layout used by modern inference runtimes (llama.cpp, ExLlamaV2, vLLM, and TensorRT-LLM):
Weights_GB = (Parameters_Billions × Bits_Per_Weight) / 8
KV_GB = (2 × Layers × KV_Heads × Head_Dim × Context × (KV_Bits / 8)) / 1024³
Speed = (Memory_Bandwidth_GBs × 0.72) / Active_Weights_GB
Frequently Asked Questions
How much VRAM do I need to run an 8.03B Parameter LLM locally?
In full FP16/BF16 precision, an 8.03B Parameter LLM requires approximately 18.6 GB of VRAM including an 8,192-token KV cache and CUDA runtime buffer. Using 4-bit GGUF quantization (Q4_K_M at 4.85 bits per weight), total VRAM drops to 7.4 GB, while 8-bit quantization (Q8_0) requires 11.0 GB.
What is the difference between GGUF (Q4_K_M), EXL2, and AWQ quantization?
GGUF (used by llama.cpp, Ollama, and LM Studio) supports both pure GPU execution and hybrid CPU+GPU RAM offloading, making Q4_K_M the most versatile format. EXL2 (ExLlamaV2) runs strictly inside GPU VRAM and offers fine-grained bitrates (e.g., 3.5, 4.0, 4.25, 6.0 bpw) with maximum single-user tokens/sec. AWQ (Activation-aware Weight Quantization) is optimized for high-concurrency production inference engines like vLLM and TensorRT-LLM.
How does Context Window (KV Cache) affect GPU VRAM consumption?
Every token in your active context window stores Key and Value tensors across all transformer layers. With Grouped-Query Attention (GQA), KV cache memory equals 2 * Layers * KV_Heads * Head_Dim * Context_Tokens * Bytes_Per_Element. Quantizing the KV cache from FP16 (16-bit) to Q8_0 (8-bit) or Q4_0 (4-bit) cuts context memory overhead by 50% to 75% with minimal perplexity impact.
How are local LLM Tokens Per Second (tok/s) calculated across different GPU cards?
Autoregressive token generation (batch size 1) is memory-bandwidth bound rather than compute bound. For each generated token, the GPU must read all active model weights from VRAM into Tensor Cores. Therefore, theoretical peak speed equals Memory Bandwidth (GB/s) divided by Active Model Size (GB), typically achieving 65% to 78% efficiency in llama.cpp and ExLlamaV2.