Can I Run Phi-4 Family on Mac Studio (M3 Ultra, 256 GB)?

Written by Jakub Rusinowski · Last updated January 6, 2025

Yes — comfortably

Yes, comfortably — Phi-4 (14B) at Q8_0 needs about 17.4 GB of the 192 GB usable on Mac Studio (M3 Ultra, 256 GB), leaving ~174.6 GB spare and running at ~26.3 tok/s (estimated), with room for about 16,384 tokens of context.

Confidence: high · Recommended quantization: Q8_0 · Estimated speed: ~26.3 tok/s

Mac Studio (M3 Ultra, 256 GB) — what it gives a model

Usable memory for models	192 GB
Memory bandwidth	819 GB/s
Form factor	Desktop
Operating system	macOS
Memory upgradeable	No — soldered

Phi-4 Family on Mac Studio (M3 Ultra, 256 GB): memory by quantization

Quant	Memory needed	Fits 192 GB?	Max context	Est. speed	Download
F16	30.5 GB	✓ Yes	16K	~14.9 tok/s	28 GB
Q8_0	17.4 GB	✓ Yes	16K	~26.3 tok/s	14.9 GB
Q6_K	14 GB	✓ Yes	16K	~32.8 tok/s	11.5 GB
Q5_K_M	12.4 GB	✓ Yes	16K	~37.1 tok/s	9.9 GB
Q4_K_M	10.9 GB	✓ Yes	16K	~42.2 tok/s	8.5 GB
Q3_K_M	8.4 GB	✓ Yes	16K	~55.1 tok/s	6 GB
Q2_K	7.1 GB	✓ Yes	16K	~66.1 tok/s	4.6 GB

What to watch out for

Memory on this machine is not upgradeable, so the configuration you buy is the ceiling for every model you will ever run on it.

Mac Studio M3 Ultra 256 GB limitations

The largest single-box unified memory pool available, but at roughly half the memory bandwidth of a high-end discrete GPU — very large models load, then run slowly.
Memory is soldered; the configuration chosen at purchase is permanent.

Recommended setup

Ollama or LM Studio (Metal) — MLX for the fastest Apple-native throughput

How these numbers are calculated

Memory need = quantized weights + KV cache at 8,192 tokens (f16) + 0.8 GB runtime overhead.
256 GB unified memory at 819 GB/s, shared between CPU and GPU.
macOS reserves a share of unified memory for the system, so not all of it is available to a model.
Throughput is a memory-bandwidth roofline estimate, not a measurement. It is labelled "estimated" everywhere it appears.
KV cache is computed from this model's published attention configuration.

FAQ

Can I run Phi-4 Family on Mac Studio (M3 Ultra, 256 GB)?

Which quantization of Phi-4 Family should I use on Mac Studio (M3 Ultra, 256 GB)?

Q8_0 — it needs about 17.4 GB of the 192 GB available, downloads as roughly 14.9 GB, and runs at an estimated 26.3 tokens/sec with up to 16K of context.

What limits Phi-4 Family on Mac Studio (M3 Ultra, 256 GB)?

Nothing binding — the model fits with headroom and generates at a usable speed on this hardware.

Can I Run Phi-4 Family on Mac Studio (M3 Ultra, 256 GB)?

Mac Studio (M3 Ultra, 256 GB) — what it gives a model

Phi-4 Family on Mac Studio (M3 Ultra, 256 GB): memory by quantization

What to watch out for

Mac Studio M3 Ultra 256 GB limitations

Recommended setup

How these numbers are calculated

FAQ

Can I run Phi-4 Family on Mac Studio (M3 Ultra, 256 GB)?

Which quantization of Phi-4 Family should I use on Mac Studio (M3 Ultra, 256 GB)?

What limits Phi-4 Family on Mac Studio (M3 Ultra, 256 GB)?

Which runtime should I use?

Other Computers

Other Models on Mac Studio (M3 Ultra, 256 GB)

Phi-4 Family on GPUs

What This Model Is Good At

Model & Tools