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Apple M3 Ultra (256GB)

The Apple M3 Ultra (256GB) uses a unified memory architecture. For reliable local LLM inference without OS memory pressure, this benchmark models a 75% usable allocation (192 GB) with 819 GB/s unified memory bandwidth.

Memory

256 GB

Usable Memory Ceiling

192 GB (75% usable budget)

Bandwidth

819.2 GB/s

Max Inference Class

70B+ Models (Q4)

TDP

250W

VRAM Scaling by Context Length

Estimated memory requirements as context length increases. Curves crossing above the reference line indicate Out of Memory (OOM).

DeepSeek-R1 14B (14B)Qwen2.5-32B (32B)Qwen3.5-122B-A10B (122B (10B active))DeepSeek V4.1 Flash (552B (16B active))

Precision:

Best Models to Run on Apple M3 Ultra (256GB)

Inference throughput, memory compatibility, and generation speeds for open-weights LLMs on Apple M3 Ultra (256GB).

Sort by:

Context:

KV Cache:

RankModelParametersPrecisionTPS (Approx.)TTFTCan Run

#30

DeepSeek-V4-Flash-Vision-Exp

290.9B (20.4B active)

INT4

52 tok/s

~6.9s

#33

Qwen 3.8 27B

27B

INT4
Q8
FP16

39 tok/s

23 tok/s

12 tok/s

~9.5s

~9.6s

~9.6s

#40

MiMo-V2.6-Flash

309B

INT4

4 tok/s

~116.3s

#41

Qwen 3.8 Flash

176B (6B active)

INT4
Q8

123 tok/s

79 tok/s

~2.1s

~2.2s

#42

DeepSeek-V4-Flash

284B (13B active)

INT4

74 tok/s

~4.4s

#43

K2 Horizon 375B A23B

375B (23B active)

INT4

31 tok/s

~13.1s

#48

Agnes 3.0 Flash

33B

INT4
Q8
FP16

33 tok/s

19 tok/s

10 tok/s

~11.6s

~11.6s

~11.7s

#61

Sarvam-105B

106B (10.3B active)

INT4
Q8

83 tok/s

53 tok/s

~4.9s

~4.9s

#72

K2 Horizon MoVA 36B A4B

36B (4B active)

INT4
Q8
FP16

131 tok/s

99 tok/s

63 tok/s

~1.9s

~1.9s

~1.9s

#75

Ling 3.0 Flash VL

124B (5.5B active)

INT4
Q8

120 tok/s

84 tok/s

~3.5s

~3.5s

#80

GLM-5.3 Flash

313.3B (17.3B active)

INT4

56 tok/s

~6.4s

#82

Qwen3 235B A22B Thinking

235B (22B active)

INT4

16 tok/s

~9.6s

#83

Qwen3.5-27B

27B

INT4
Q8
FP16

39 tok/s

23 tok/s

12 tok/s

~9.5s

~9.6s

~9.6s

#84

Qwen3.5-122B-A10B

122B (10B active)

INT4
Q8

67 tok/s

47 tok/s

~5.0s

~5.0s

#92

Sarvam-30B

32B (2.4B active)

INT4
Q8
FP16

159 tok/s

128 tok/s

89 tok/s

~1.3s

~1.3s

~1.3s

#94

Qwen3.6 35B A3B

35B (3B active)

INT4
Q8
FP16

147 tok/s

115 tok/s

77 tok/s

~1.5s

~1.5s

~1.5s

#96

Muse Glimmer 30B

30B

INT4
Q8
FP16

36 tok/s

21 tok/s

11 tok/s

~10.6s

~10.6s

~10.6s

#100

Phi-4 Reasoning Plus

14B

INT4
Q8
FP16

51 tok/s

35 tok/s

21 tok/s

~5.0s

~5.0s

~5.1s

#101

MiMo V2 Flash

15B (309B active)

INT4
Q8
FP16

4 tok/s

2 tok/s

1 tok/s

~104.4s

~104.6s

~105.0s

#105

Inkling-Small

276B (12B active)

INT4

15 tok/s

~7.3s

Inference Capacity

Maximum model parameter class runnable by weight precision.

Context:

4-bit

Q4

70B+ Models

8-bit

Q8

70B Models

16-bit

FP16

70B Models

Fine-Tuning Capacity

Hardware capacity for local training and adapter fine-tuning.

Context Length:

QLoRA

4-bit

70B+ Models

LoRA

16-bit

70B Models

Full Parameter Training

7B-8B Models

Workload Recommendations

Guidance for optimal precision and operational ceilings on Apple M3 Ultra (256GB).

Inference Sweet Spot

Suitable for 70B parameter models at Q4/Q8 with extended 32k context windows, or high-throughput batching of smaller dense architectures.

Bandwidth & Speed Profile

With 819.2 GB/s aggregate bandwidth, batch size 1 inference operates in a memory-bandwidth bound regime. Generates approximately 182 tok/s on an 8B Q4 model and 22 tok/s on a 70B Q4 model.

Unified Memory Budget

Modeled with a 75% usable allocation budget to preserve system RAM for macOS and display compositor processes.

Frequently Asked Questions