Decision-first: Budget file size + KV(context) + overhead, not file size — and on unified memory, subtract OS + co-resident workloads first. “Barely fits” means doesn’t fit. Size memory by total params, speed by active params.

Scope & freshness: General sizing principles (version-independent); worked numbers from 2026-05 on a GB10 (128 GB unified) + a 64 GB Apple-Silicon Mac. Re-measure resident sizes for your model/quant/context.

Resident size is bigger than the file#

The single most common sizing mistake is equating the model file size with how much memory it needs at runtime. Resident footprint is: