est. tokens / second
How the estimate works
Fit: weights ≈ parameters × bits-per-weight ÷ 8, plus ~10% runtime overhead, plus a KV cache that grows with context length. Unified-memory machines (Macs, DGX Spark, Strix Halo) reserve a slice for the OS, so usable memory is less than the sticker number.
Speed: generation is memory-bandwidth-bound — every new token streams the whole model through memory. Estimated tok/s ≈ bandwidth ÷ model size × ~65% real-world efficiency. Prompt processing is compute-bound and much faster; this estimates generation.
Honesty: these are planning estimates for dense models. Mixture-of-experts models run faster than their size suggests. We validate this math against real runs on real hardware in Lab Notes — published methodology, raw numbers.
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