Local AI Hardware Fit Lab

Assumption-transparent estimator for running LLMs on your own hardware. All performance figures are illustrative heuristics, not measured benchmarks.

Hardware Profile

Model & Workload

Memory Map (weights / KV / runtime / OS / margin)

Results & Fit

Checking…

Bandwidth-limited throughput

Illustrative: decode speed ≈ bandwidth ÷ weight bytes read per token, split across concurrent streams.

Scenario Comparison

Duplicate the current configuration to compare setups side by side.

Local vs Cloud Comparison

The quality gap cannot be reduced to one number: frontier cloud models generally lead on hard reasoning and breadth, while a well-chosen local model can be excellent for private document Q&A, extraction, drafting, and offline work. Local can win on privacy, availability, customization, and learning even when cloud is cheaper or more capable.

Hybrid Workload Planner

Rules: private or offline → local; quality-critical and not private → cloud; bursty and not private → cloud; latency-sensitive small tasks → local; mixed signals → hybrid (local first, cloud escalation).

Learning Chapters

Parameters & quantization

Parameter count sets the raw memory footprint: bytes ≈ params × bits ÷ 8. Quantizing from 16-bit to 4-bit cuts weight memory ~4× with modest quality loss for many tasks; below 3-bit, degradation grows quickly.

KV cache & context length

Every token in context stores key/value activations per layer. KV memory grows linearly with context, batch, and concurrency, and can exceed the weights themselves at long contexts.

Memory bandwidth & tokens/sec

Decoding reads most weights once per generated token, so tokens/sec is often bandwidth ÷ weight size, not raw FLOPS. This is why unified-memory machines with high bandwidth punch above their compute class.

Unified vs discrete memory

Discrete GPUs have fast but small VRAM; unified memory offers larger pools at moderate bandwidth. A model that spills out of VRAM to system RAM typically slows drastically.

Local privacy & hybrid routing

Local inference keeps data on your machine, works offline, and is fully customizable. Hybrid routing sends private or latency-sensitive work locally and escalates hard, quality-critical requests to a cloud model.

Why model quality varies by task

Small models can rival large ones on narrow tasks like extraction or retrieval-grounded Q&A, while lagging on multi-step reasoning and broad knowledge. Match model size to the task rather than assuming one answer.

Knowledge Check

Assumptions & Formulas

weights_GB = params_B × bits/8 × 1.1 (10% overhead)
kv_GB = params_B × 0.00012 × context × batch × concurrency ÷ 1.024 (≈0.12 MB/token per 1B params at 16-bit KV)
tok/s ≈ bandwidth_GBs ÷ weights_GB × efficiency(0.5/0.65/0.8 by compute class) ÷ concurrency
TTFT ≈ context ÷ (prefill = 300 × params-scaled compute factor)
electricity $/mo = W ÷ 1000 × hrs/day × 30 × $/kWh; local monthly cost = price ÷ lifetime + electricity. Breakeven month = price ÷ (cloud spend − electricity) when positive. OS reserve 4 GB (discrete GPU: 1 GB of VRAM), runtime 1.5 GB, safety margin 8% of pool. All outputs are illustrative estimates; this page never inspects your machine or runs benchmarks.