Why most LLM VRAM calculators are wrong on modern models (and an open-source MIT fix)

🔗 Try it — free, no signup: fitllm.run ⭐ Open source (MIT, one file): github.com/click6067-ship-it/fitllm-engine Most "can I run this LLM?" calculators estimate the KV cache with the textbook formula: KV ≈ 2 × layers × kv_heads × head_dim × context × bytes It assumes every layer keeps a full-context KV cache with one head shape. True for Llama-1/2 — wrong for most 2025–2026 models: Gemma 4 is a 5:1 sliding-window:global interleave — most layers only hold the last 1024 tokens, and...