Phi 3 Mini 3.8B needs ~36.7 GB VRAM. Mac Studio M3 Ultra 256GB has 184.3 GB. With Q4_K_M quantization, expect ~53 tok/s.
Operating mode
Interactive favors responsiveness, while light API and scale-out lean harder on serving readiness. The fit stays the same, but the recommendation lens changes.
Current mode
Balanced
Balanced for general local use. Keeps the ranking neutral across personal and serving workflows.
Select quantization to explore
Fit status
Runs well
Decode
53.2 tok/s
TTFT
3639 ms
Safe context
128K
Memory
36.7 GB / 184.3 GB
This setup is broadly balanced for this model.
Shared-memory contention still exists
The OS, browser, and inference runtime all compete for the same physical memory pool, so real-world headroom is less forgiving than raw capacity suggests.
| Workload | Grade | Fit | Decode | TTFT | Context |
|---|---|---|---|---|---|
| Chat | B | Runs well | 53.2 tok/s | 1985 ms | 128K |
| Coding | B | Runs well | 53.2 tok/s | 3639 ms | 128K |
| Agentic Coding | B | Runs well | 53.2 tok/s | 5293 ms | 128K |
| Reasoning | B | Runs well | 53.2 tok/s | 4301 ms | 128K |
| RAG | B | Runs well | 53.2 tok/s | 6617 ms | 128K |
How Phi 3 Mini 3.8B (3.799999952316284B params) fits at each quantization level on Mac Studio M3 Ultra 256GB (184.3 GB usable).
| Quant | Bits | VRAM | Quality | Fit |
|---|---|---|---|---|
Q2_K | 2 | 1.5 GB | Low | C54 |
Q3_K_S | 3 | 1.9 GB | Low | C54 |
NVFP4 | 4 |
Copy-paste commands to run Phi 3 Mini 3.8B on your machine.
Run
ollama run phi3:miniYes, Mac Studio M3 Ultra 256GB can run Phi 3 Mini 3.8B with a B grade (Runs well). Expected decode speed: 53.2 tok/s.
Phi 3 Mini 3.8B (3.799999952316284B parameters) requires approximately 36.7 GB of memory with Q4_K_M quantization.
The recommended quantization for Phi 3 Mini 3.8B is Q4_K_M, which balances quality and memory efficiency.
On Mac Studio M3 Ultra 256GB, Phi 3 Mini 3.8B achieves approximately 53.2 tokens per second decode speed with a time-to-first-token of 3639ms using Q4_K_M quantization.
For coding workloads, Phi 3 Mini 3.8B on Mac Studio M3 Ultra 256GB receives a B grade with 53.2 tok/s and 128K context.
On Mac Studio M3 Ultra 256GB, Phi 3 Mini 3.8B can safely use up to 128K tokens of context. The model's official context limit is 128K, but available memory constrains the safe maximum.
Paste this snippet into any page to show a live fit card.
<iframe src="https://willitrunai.com/embed/phi-3-mini-3.8b-on-m3-ultra-256gb" width="400" height="180" frameborder="0" style="border:none;border-radius:12px;overflow:hidden;" title="Will It Run AI — fit result"></iframe>
Preview:
2.1 GB |
| Medium |
| C54 |
Q4_K_M | 4 | 2.3 GB | Medium | C54 |
Q5_K_M | 5 | 2.7 GB | High | C54 |
Q6_K | 6 | 3.1 GB | High | C54 |
Q8_0 | 8 | 4.1 GB | Very High | C54 |
F16Best for your GPU | 16 | 7.8 GB | Maximum | C54 |
Not always. Mac Studio M3 Ultra 256GB can often fit larger models thanks to unified memory, but a discrete GPU with dedicated high-bandwidth VRAM may still decode faster once the model fits. For this combination, the important distinction is capacity versus sustained throughput.