What can an M3 Pro with 18 GB run?

20 of 73 open models run well on it. The GPU can use about 14 GB of its 18 GB by default, and it reads memory at 150 GB/s, which sets how fast it writes. Found in: MacBook Pro (14-inch, M3 Pro or M3 Max, Nov 2023), MacBook Pro (16-inch, Nov 2023).

Smartest that runs wellMiniCPM5 2B8-bit · 2.7 GB · 25–44 tok/sBiggest that runs wellGemma 4 12B Unified4-bit · 6.7 GB · 10–18 tok/s

Runs well 27

Fits with room for context, at 10 or more tokens a second.

ModelVersionMemoryTokens/s
MiniCPM5 2B2.52B · Intelligence 12.58-bit2.7 GB25–44
Qwen3.5 9B9B · Intelligence 11.24-bit5.1 GB13–24
Granite 4.2 8B8B · Intelligence 11.16-bit6.5 GB10–18
Granite 4.2 3B3B · Intelligence 9.18-bit3.2 GB21–38
Gemma 4 E4B8B · Intelligence 8.98-bit8.5 GB14–25
Ministral 3 8B8.9B · Intelligence 5.54-bit5 GB14–24
Nemotron 3 Nano 4B3.97B · Intelligence 4.88-bit4.2 GB16–29
Gemma 4 12B Unified12B4-bit6.7 GB10–18
Qwen3 8B8.2B6-bit6.7 GB10–18
Llama 3.1 8B Instruct8B6-bit6.5 GB10–18
Gemma 4 E2B5.1B8-bit5.4 GB28–50
Qwen3.5 4B4B8-bit4.3 GB16–28
Phi-4 mini instruct3.8B8-bit4 GB17–30
Llama 3.2 3B Instruct3.21B8-bit3.4 GB20–35
SmolLM3 3B3B8-bit3.2 GB21–38
LFM2.5 2.6B2.69B8-bit2.9 GB23–41
Qwen3.5 2B2B8-bit2.1 GB32–57
Llama 3.2 1B Instruct1.23B8-bit1.3 GB52–92
Qwen3.5 0.8B0.8B8-bit0.9 GB75–133
Qwen3 0.6B0.6B8-bit0.6 GB113–200
Qwen3.6 35B A3B35B · 3B active · Intelligence 18.22-bit lower quality10.9 GB75–133
Nemotron 3.5 Lightning 30B A3B30B · 3B active · Intelligence 12.92-bit lower quality9.4 GB75–133
Nemotron 3 Nano 30B A3B30B · 3.5B active · Intelligence 8.92-bit lower quality9.4 GB61–109
Qwen3 Coder 30B A3B Instruct30.5B · 3.3B active2-bit lower quality9.5 GB68–120
GLM-4.7 Flash30B · 3B active2-bit lower quality9.4 GB75–133
Gemma 4 26B A4B25.2B · 3.8B active3-bit lower quality11 GB40–71
LFM2.5 24B A2B24B · 2B active3-bit lower quality10.5 GB75–133

Runs, but slowly 10

Fits, but under 10 tokens a second: fine for batch work, slow for chat.

ModelVersionMemoryTokens/s
Phi-4 Reasoning Vision 15B15B4-bit8.4 GB8–14
Phi-4 (14B)14B6-bit11.4 GB6–11
Qwen3.8 27B27B · Intelligence 33.73-bit lower quality11.8 GB6–10
Muse Glimmer 30B29.6B · Intelligence 17.52-bit lower quality9.3 GB7–13
Gemma 4 31B30.7B · Intelligence 14.72-bit lower quality9.6 GB7–13
Granite 4.2 30B30B · Intelligence 12.72-bit lower quality9.4 GB7–13
Qwen3.6 27B27B3-bit lower quality11.8 GB6–10
Devstral Small 2 (24B)24B3-bit lower quality10.5 GB6–11
Magistral Small 1.2 (2509)24B3-bit lower quality10.5 GB6–11
Mistral Small 3.2 (24B)24B3-bit lower quality10.5 GB6–11

Only just fits 1

Needs almost all memory: raise the GPU memory limit and keep the context short.

ModelVersionMemoryTokens/s
gpt-oss-20b21B · 3.6B active · Intelligence 9native 4.25-bit13.8 GB36–63

Too big 35

Needs more memory than 18 GB, even at 2 bits.

Other Macs

Every Mac with 18 GB, from any chip.

The M3 Pro with more or less memory:

Neighbouring chips:

Head to head:

Compare it with any Mac or GPU · The M3 Pro for local AI · The best Mac for local LLMs · Every Mac

Questions

What is the best LLM for an M3 Pro with 18 GB?
Of the models with a published Intelligence Index, MiniCPM5 2B scores highest among those that run well here: 8-bit, about 25–44 tokens a second. The biggest that runs well is Gemma 4 12B Unified.
Can an M3 Pro with 18 GB run Llama 3.3 70B?
No: even at 2 bits it needs more than the 14 GB the GPU can use by default.
How fast is gpt-oss-20b on an M3 Pro?
About 36–63 tokens a second (native 4.25-bit), from the chip’s 150 GB/s memory bandwidth.

Run them with MLX Harness (free, open source) or Apple’s mlx-lm in Terminal: step by step.

How it’s worked out

Memory: the model’s parameters at 8, 6, 4, 3 or 2 bits per weight plus MLX’s group scales (half a bit per weight), or its native format, with room for the context on top. By default macOS lets the GPU use about 75% of unified memory. Speed: memory bandwidth divided by the bytes read per token is the ceiling for one conversation; in llama.cpp’s public Apple Silicon benchmarks real runs reach about 45% to 80% of it, which is the range shown. These are estimates, not measurements: measure your own Mac on MLX Bench. Model figures from each official model card, chip figures from Apple’s Tech Specs. Checked 2026-10-19. Same data as mlx.app/compare.

What LLMs can an M3 Pro with 18 GB run? Models and speed