Can a Mac Studio M5 Ultra, 256GB run local LLMs?
Yes — 38 of the 39 open models on this site fit in its 192 GB of usable memory, the strongest being GLM-5.3-Flash. Whether that saves you money is a different question, and the answer is usually no.
Price$10,799
Memory256 GB, about 192 GB of it addressable by the GPU at 1200 GB/s
Best model it runsGLM-5.3-Flash — Sonnet-class, 32 tok/s
Pay-back against the APIPays back in 965 years at 500k tokens a day
Run the numbers on this machine
What it runs
| Model | Speed | Class | Good at | Memory |
|---|---|---|---|---|
| GLM-5.3-FlashUD-Q4_K_M | 32 tok/s | Sonnet-class | 190 GB | |
| Qwen3.8 Flash NextQ4_K_M | 74 tok/s | Sonnet-class | 121 GB | |
| DeepSeek V4-FlashUD-Q4_K_M | 49 tok/s | Sonnet-class | 155 GB | |
| Qwen3.8 27BQ4_K_M | 48 tok/s | Sonnet-class | 19 GB | |
| Inkling SmallUD-Q4_K_M | 43 tok/s | Haiku-class | 164 GB | |
| Ling 3.0 flashQ4_K_M | 52 tok/s | Haiku-class | 82 GB | |
| MiniMax M2.7Q4_K_M | 25 tok/s | Haiku-class | 149 GB | |
| Qwen3.6 27BQ4_K_M | 47 tok/s | Haiku-class | 19 GB | |
| Qwen3.6 35B-A3BQ4_K_M | 143 tok/s | Haiku-class | 23 GB | |
| Muse Glimmer 30BQ4_K_M | 50 tok/s | Haiku-class | 18 GB | |
| Gemma 4 26B-A4BQ4_K_M | 105 tok/s | Haiku-class | 18 GB | |
| Qwen3.5 122B-A10BUD-Q4_K_M | 51 tok/s | Haiku-class | 79 GB |
26 more fit; the calculator lists them all.
The specifics
- Chip
- M5 Ultra — 36-core CPU / 80-core GPU
- Memory bandwidth
- 1200 GB/s
- Usable by the GPU
- 192 GB — macOS lets the GPU wire roughly 75% of unified memory by default (llama.cpp discussion #2182: 66.7% at 32 GiB or less, 75% above). Raise it with `sudo sysctl iogpu.wired_limit_mb`. Memory is treated as GB throughout, which is slightly conservative.
- Power under load
- 270 W (stand in) — Apple has not published power figures for the 2026 machines yet (support articles 103253 / 102027 stop at the 2024/2025 models). Stand-in: Apple's published maximum for the previous chip (M3 Ultra Mac Studio, 270 W), which is a CPU+GPU stress figure, so it likely overstates inference draw.
- Availability
- Pre-order; ships 2026-09-22.
- Sources
- source 1, source 2, source 3