GPT-OSS 20B is a 20.91B-parameter mixture-of-experts model (3.6B active per token). At MXFP4 it needs about 12.9 GB of memory. The MacBook M2 Pro 16GB has 12 GB usable, so it doesn't fit, even at its smallest quantization.
| Quantization | File size | Memory | Generation | First token | Source |
|---|---|---|---|---|---|
| MXFP4 | 12.1 GB | Doesn't fit | Won't run | — | — |
All models on the MacBook M2 Pro 16GB · GPT-OSS 20B on all hardware
Estimates for a short prompt on a single device. Measured numbers come from community benchmarks (r/LocalLLaMA, localscore.ai and more); others are derived from similar setups or projected from specs. Open source on GitHub.