GPT-oss 20B runs at 184 tok/s on a 256 GB M5 Ultra, a community run reported by bohemiansilicon.com (MLX, MXFP4, 512-token random prompt, 128 generated, empty context, mean of 2). It needs about 13 GB of unified memory. It is OpenAI's 21B mixture-of-experts model (3.6B active), released under the Apache 2.0 licence.
Want to run GPT-oss 20B faster — or step up to bigger models? Find your Mac →This is a community run: a real run, reported by its source and linked below. The index records it as given and never adjusts it.
| Metric | Value |
|---|---|
| Tokens per second | community184 tok/s |
| Provenance | community run · bohemiansilicon.com |
| Quantization | MXFP4 |
| Engine | MLX |
| Context | 512-token random prompt, 128 generated, empty context, mean of 2 |
| Figure dated | 2026-10-15 |
| Minimum RAM | 13 GB |
| Parameters | 21B MoE (3.6B active) |
| Chip bandwidth | 1228 GB/s |
Each row as the index holds it, with its source. “Mac RAM” is the memory of the Mac a run used, not the model’s requirement (13 GB). The headline figure follows the reference rule: the lower-median measured plain-decode run at 5 bits or fewer (a run whose quant was not stated counts only when no stated-quant run qualifies), else the estimate; a run marked “not used to anchor estimates” is listed here but never becomes the headline.
| Speed | Quant | Engine | Mac RAM | Context | Source | Note |
|---|---|---|---|---|---|---|
| community184 tok/s | MXFP4 | MLX | 256 GB | 512-token random prompt, 128 generated, empty context, mean of 2 | bohemiansilicon.com | Mac Studio, mlx-lm 0.32 on macOS 27.0.1, mlx-community MXFP4-Q8 build (MXFP4 experts, 8-bit elsewhere). 172 tok/s at 8K and 145 at 32K. Published by Bohemian Silicon, which rents out this Mac. |
Ollama — install it (brew install ollama or the app from ollama.com), then pull the model by its tag, checked on ollama.com on 2026-10-24:
MLX — pick a build from Hugging Face’s MLX listings, then run it with its repo id:
Downloads: Search the Ollama library → · model card →
The 184 tok/s figure above came from MLX at MXFP4; other runtimes and quants run at different speeds.
Prefer a GUI? LM Studio downloads GGUF and MLX builds in one click. Step by step: install Ollama on a Mac.
OpenAI's Apache 2.0 open-weight MoE (Aug 2025): 21B total, 3.6B active, shipped in MXFP4 so it runs in 16 GB. Model card: SWE-bench Verified 53.2, GPQA Diamond 58.6 at medium reasoning. tbreak's review measured 107.5 tok/s on an M5 Max in Ollama, and a community LM Studio run measured ~45 tok/s on a 32 GB Mac mini M6.
Apache 2.0 licence · 21B MoE · 128K context · LLMCheck capability 22/50 · see its leaderboard rank →
GPT-oss 20B needs about 13 GB of unified memory. These current Apple Silicon Macs have the headroom to run it comfortably:
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