Mac M3 Pro 18G — what LLMs can it run?
57 of 110 indexed models fit comfortably in 18GB at 4K context, each at the highest-quality quant that still leaves headroom.
The short answer for Mac M3 Pro 18G
18 GB, 150 GB/s Unified LPDDR5. 57 of 110 models in this index fit comfortably at 4K context; 59 load at all.
- Biggest that fits
- GPT-OSS 20B — 11.3 GB at Q4_K_M — 2.2 GB spare at 4K, so longer context comes out of a thin margin.
- Room to grow
- Llama 3.2 11B Vision Instruct — 7.7 GB at Q4_K_M — under 60% of the card, which leaves 5.8 GB for a long context window or a second process.
- Speed ceiling
- Llama 3.1 8B Instruct at Q4_K_M reads 4.6 GB of weights per token, so 150 GB/s puts a hard ceiling near 32 tok/s. That is arithmetic on two published numbers, not a benchmark — real throughput lands below it. No run on this card has been measured here, so there is nothing to compare the ceiling against.
- The wall you will hit
- The GPU's share of unified memory, not the 18 GB on the box. macOS reserves part of the pool for the system and caps what a single process may wire down, so the practical budget is meaningfully below nameplate — the limit is adjustable (`iogpu.wired_limit_mb`) but it is not absent. Bandwidth is 150 GB/s, which is the number that decides tok/s once a model fits.
32B · 1
| Model | Quant | Est. VRAM | Headroom | tok/s |
|---|---|---|---|---|
| GPT-OSS 20B21B MoE | Q4_K_M | 11.32 GB | +2.2 GB | ≤86Ceiling |
14B · 17
| Model | Quant | Est. VRAM | Headroom | tok/s |
|---|---|---|---|---|
| DeepSeek-Coder-V2-Lite Instruct16B-A2.4B | Q4_K_M | 10.08 GB | +3.4 GB | ≤109Ceiling |
| DeepSeek-V2-Lite Chat16B-A2.4B | Q4_K_M | 10.08 GB | +3.4 GB | ≤109Ceiling |
| StarCoder2 15B15B | Q4_K_M | 10.19 GB | +3.3 GB | 13–17Derived |
| Qwen3 14B Instruct14B | Q5_K_M | 11.65 GB | +1.8 GB | 11–15Derived |
| Qwen2.5 14B Instruct14B | Q5_K_M | 11.73 GB | +1.8 GB | 11–15Derived |
| DeepSeek-R1-Distill-Qwen-14B14B | Q4_K_M | 10.14 GB | +3.4 GB | 13–17Derived |
| Phi-4 14B14B | Q5_K_M | 11.77 GB | +1.7 GB | 11–15Derived |
| Phi-3 Medium 14B Instruct14B | Q4_K_M | 9.73 GB | +3.8 GB | 14–18Derived |
| Mistral Nemo 12B Instruct12B | Q6_K | 11.14 GB | +2.4 GB | 12–15Derived |
| Gemma 3 12B IT12B | Q5_K_M | 9.84 GB | +3.7 GB | 13–18Derived |
| Mellum2.1 12B-A2.5B Thinking12B-A2.5B | Q4_K_M | 8.59 GB | +4.9 GB | ≤95Ceiling |
| Stable LM 2 12B Chat12B | Q4_K_M | 8.35 GB | +5.2 GB | 16–21Derived |
| Llama 3.2 11B Vision Instruct11B | Q4_K_M | 7.66 GB | +5.8 GB | 17–23Derived |
| Solar 10.7B Instruct11B | Q4_K_M | 7.6 GB | +5.9 GB | 18–24Derived |
| Falcon 3 10B Instruct10B | Q4_K_M | 7.28 GB | +6.2 GB | 18–24Derived |
| Gemma 2 9B Instruct9B | Q8_0 | 11.7 GB | +1.8 GB | 12–16Derived |
| Qwen3.5 9B9B | Q8_0 | 10.37 GB | +3.1 GB | 12–16Derived |
7B · 25
| Model | Quant | Est. VRAM | Headroom | tok/s |
|---|---|---|---|---|
| GLM-4-9B-Chat9B | Q8_0 | 10.16 GB | +3.3 GB | 12–16Derived |
| Qwen3-VL 8B Instruct8B | Q8_0 | 10.39 GB | +3.1 GB | 12–16Derived |
| Granite 4.2 8B8B | Q8_0 | 10.45 GB | +3.1 GB | 12–16Derived |
| Ministral 3 8B Instruct8B | Q8_0 | 10.02 GB | +3.5 GB | 13–17Derived |
| Qwen2-VL 7B Instruct7B | Q4_K_M | 5.49 GB | +8 GB | 23–31Derived |
| Granite 3.1 8B Instruct8B | Q4_K_M | 5.88 GB | +7.6 GB | 23–31Derived |
| Qwen3 8B Instruct8B | Q6_K | 7.64 GB | +5.9 GB | 17–23Derived |
| Llama 3.1 8B Instruct8B | Q8_0 | 9.47 GB | +4 GB | 14–18Derived |
| Nous Hermes 3 Llama 3.1 8B8B | Q4_K_M | 5.64 GB | +7.9 GB | 24–32Derived |
| Aya 23 8B8B | Q4_K_M | 5.64 GB | +7.9 GB | 24–32Derived |
| OpenChat 3.6 8B8B | Q4_K_M | 5.64 GB | +7.9 GB | 24–32Derived |
| DeepSeek-R1-Distill-Llama-8B8B | Q5_K_M | 6.51 GB | +7 GB | 20–27Derived |
| InternLM2 7B Chat7B | Q4_K_M | 5.45 GB | +8.1 GB | 25–33Derived |
| Qwen2.5 7B Instruct7B | Q6_K | 6.77 GB | +6.7 GB | 19–25Derived |
| Qwen2.5-Coder 7B Instruct7B | Q4_K_M | 5.07 GB | +8.4 GB | 25–33Derived |
| DeepSeek-R1-Distill-Qwen-7B7B | Q4_K_M | 5.07 GB | +8.4 GB | 25–33Derived |
| Gemma 4 E4B ITE4B | Q8_0 | 8.46 GB | +5 GB | 15–19Derived |
| OLMo 2 7B Instruct7B | Q8_0 | 10.3 GB | +3.2 GB | 15–20Derived |
| OLMo 3 7B Instruct7B | Q8_0 | 10.3 GB | +3.2 GB | 15–20Derived |
| WizardLM-2 7B7B | Q4_K_M | 5.14 GB | +8.4 GB | 26–35Derived |
| Mistral 7B Instruct v0.37B | Q6_K | 6.75 GB | +6.8 GB | 20–26Derived |
| Zephyr 7B Beta7B | Q6_K | 6.75 GB | +6.8 GB | 20–26Derived |
| Gemma 4 E2B ITE2B | Q8_0 | 5.2 GB | +8.3 GB | ≤32Ceiling |
| Qwen3.5 4B4B | Q8_0 | 4.97 GB | +8.5 GB | ≤34Ceiling |
| Gemma 3 4B IT4B | Q8_0 | 5.05 GB | +8.5 GB | ≤35Ceiling |
≤3B · 14
| Model | Quant | Est. VRAM | Headroom | tok/s |
|---|---|---|---|---|
| Qwen3 4B Instruct4B | Q6_K | 4.05 GB | +9.5 GB | ≤48Ceiling |
| Phi-4 Mini Instruct3.8B | Q8_0 | 4.81 GB | +8.7 GB | ≤39Ceiling |
| Phi-3.5 Mini Instruct3.8B | Q8_0 | 5.89 GB | +7.6 GB | ≤39Ceiling |
| Granite 4.2 3B3B | Q8_0 | 4.41 GB | +9.1 GB | ≤41Ceiling |
| Llama 3.2 3B Instruct3B | Q8_0 | 4.05 GB | +9.5 GB | ≤46Ceiling |
| Qwen2.5 3B Instruct3B | Q8_0 | 3.59 GB | +9.9 GB | ≤48Ceiling |
| SmolLM3 3B3B | Q8_0 | 3.73 GB | +9.8 GB | ≤48Ceiling |
| Gemma 2 2B Instruct2B | Q8_0 | 3.34 GB | +10.2 GB | ≤57Ceiling |
| Qwen3.5 2B2B | Q8_0 | 2.23 GB | +11.3 GB | ≤76Ceiling |
| Qwen3 1.7B Instruct1.7B | Q8_0 | 2.39 GB | +11.1 GB | ≤86Ceiling |
| Qwen2.5 1.5B Instruct1.5B | Q8_0 | 1.83 GB | +11.7 GB | ≤97Ceiling |
| Llama 3.2 1B Instruct1B | Q8_0 | 1.51 GB | +12 GB | ≤120Ceiling |
| Qwen3.5 0.8B0.8B | Q8_0 | 0.94 GB | +12.6 GB | ≤185Ceiling |
| Qwen2.5 0.5B Instruct0.5B | Q8_0 | 0.6 GB | +12.9 GB | ≤306Ceiling |
How this list is built
Each row is the lowest-perplexity-loss quant of that model whose estimated total — weights plus KV cache at 4K context plus activation buffer — uses at most 88% of the card. That is the calculator's "green" threshold, so every row here has real headroom rather than only just fitting. Raise the context length and the list shortens; the calculator lets you check any combination directly. The speed column is this card: a measured run, a range scaled from this card's own Llama 2 7B benchmark, or a bandwidth ceiling. A figure that only exists for the RTX 4090 is labelled as that card.
A further 2 models load but with no headroom to spare (up to 105% of VRAM) — the Quant Hub’s GPU chips count those too, which is why its number is higher.
Measured on this card
No benchmark runs in this index were recorded on a Mac M3 Pro 18G. Every figure on this page is calculated from the model architecture and the quant level — treat them as estimates, not measurements.
Setup guides for this card
Step-by-step guides written for the Mac M3 Pro 18G's runtime or memory size, with the commands and the checks that prove the model is running on the card.
Stepping up
A Mac M4 Pro 24G (24GB) fits 8 more of the indexed models than this card. Mac M4 Pro 24G →
Before buying, hear the speed difference on a model both cards hold: Mac M3 Pro 18G vs Mac M4 Pro 24G (Qwen3 14B Instruct) →
Common questions
What is the best local LLM for a Mac M3 Pro 18G?
For everyday use, Llama 3.2 11B Vision Instruct at Q4_K_M — about 7.7 GB of the card's 18 GB at 4K context, leaving 5.8 GB for a longer window. If you want the largest thing that will load, that is GPT-OSS 20B at Q4_K_M (11.3 GB, 2.2 GB spare). "Best" here means best fit for the memory budget — this index does not run task benchmarks, so it cannot tell you which model is smarter.
Can a Mac M3 Pro 18G run ERNIE 4.5 21B-A3B?
Only just. Its smallest build here, Q4_K_M, needs about 14.1 GB against 13.5 GB usable — that loads with nothing else running, with no margin for a longer context window. It is not on the list above, which requires a model to stay inside 88% of usable capacity.
How many tokens per second does a Mac M3 Pro 18G do on an 8B model at Q4?
This index has no measured run on this card, so it does not publish a figure. What can be stated from specifications: generating a token requires reading every weight once, Llama 3.1 8B Instruct at Q4_K_M is 4.6 GB of weights, and this card moves 150 GB/s — a ceiling near 32 tok/s. Batch size, context length, the runtime and how much of the model sits in cache all take you below it.
Mac M3 Pro 18G or Mac M3 16G for local LLMs?
They do not hold the same set: Mac M3 Pro 18G fits 57 and Mac M3 16G 56 of 110 at 4K — macOS keeps part of the Mac M3 Pro 18G's unified memory from the GPU, leaving about 14 GB usable. Speed is the other difference — 150 GB/s against 100 GB/s, a 1.5× gap in how fast the weights can be read, which is what token generation is bound by. The Mac M3 Pro 18G generates faster on any model both can hold.
57 of 110 indexed models fit comfortably in 18GB at 4K context, each at the highest-quality quant that still leaves headroom.
This page's figures change when the model or the runtime does.Last updated 2026-10-18 RSS → /feed.xml