Qwen3.5 4B needs ~17.6 GB VRAM. Mac Studio M1 Ultra 128GB has 92.2 GB. With Q4_K_M quantization, expect ~56 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
56.0 tok/s
TTFT
3457 ms
Safe context
2.6M
Memory
17.6 GB / 92.2 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 | C | Runs well | 56.0 tok/s | 1886 ms | 2.6M |
| Coding | C | Runs well | 56.0 tok/s | 3457 ms | 2.6M |
| Agentic Coding | C | Runs well | 56.0 tok/s | 5029 ms | 2.6M |
| Reasoning | C | Runs well | 56.0 tok/s | 4086 ms | 2.6M |
| RAG | C | Runs well | 56.0 tok/s | 6286 ms | 2.6M |
Inference speed
Estimated decode speed (tokens/sec) for Qwen3.5 4B at Q4_K_M across popular GPUs and Apple Silicon, using the fastest local runtime per device. Fastest is RTX 5090 32GB at ~76 tok/s. Speed is memory-bandwidth bound, so cards that fit the whole model in VRAM run far faster than ones that offload to system RAM.
| GPU / Mac | Memory | Quant | Speed (tok/s) | Fits? |
|---|---|---|---|---|
 RTX 5090 32GB | 32 GB | Q4_K_M | 76.0 | Fits |
| RTX 4090 24GB | 24 GB | Q4_K_M | 64.0 | Fits |
| RTX 4080 Super 16GB | 16 GB | Q4_K_M | 64.0 | Fits |
| RTX 3090 24GB | 24 GB | Q4_K_M | 56.0 | Fits |
| RTX 4070 12GB | 12 GB | Q4_K_M | 56.0 | Fits |
| RTX 3060 12GB | 12 GB | Q4_K_M | 56.0 | Fits |
| RTX 4060 8GB | 8 GB | Q4_K_M | 56.0 | Fits |
RX 7900 XTX 24GB | 24 GB | Q4_K_M | 56.0 | Fits |
MacBook Pro M4 Max 128GB | 128 GB | Q4_K_M | 56.0 | Fits |
Mac Studio M3 Ultra 256GB | 256 GB | Q4_K_M | 56.0 | Fits |
Mac Studio M2 Ultra 128GB | 128 GB | Q4_K_M | 56.0 | Fits |
Mac Studio M1 Ultra 128GB | 128 GB | Q4_K_M | 56.0 | Fits |
MacBook Pro M4 Max 64GB | 64 GB | Q4_K_M | 56.0 | Fits |
MacBook Pro M3 Max 64GB | 64 GB | Q4_K_M | 56.0 | Fits |
MacBook Pro M1 Max 64GB | 64 GB | Q4_K_M | 56.0 | Fits |
MacBook Pro M4 Pro 48GB | 48 GB | Q4_K_M | 56.0 | Fits |
Estimates for single-stream decoding at Q4_K_M; real tokens/sec varies with prompt length, context, batch size, and runtime build. Prompt processing (prefill) is faster than the decode figures shown here.
How Qwen3.5 4B (4B params) fits at each quantization level on Mac Studio M1 Ultra 128GB (92.2 GB usable).
| Quant | Bits | VRAM | Quality | Fit |
|---|---|---|---|---|
Q2_K | 2 | 1.6 GB | Low | D39 |
Q3_K_S | 3 | 2.0 GB | Low | D39 |
NVFP4 | 4 | 2.2 GB | Medium | D39 |
Q4_K_M | 4 | 2.4 GB | Medium | D39 |
Q5_K_M | 5 | 2.9 GB | High | D39 |
Q6_K | 6 | 3.3 GB | High | D39 |
Q8_0 | 8 | 4.3 GB | Very High | D40 |
F16Best for your GPU | 16 | 8.2 GB | Maximum | D40 |
Copy-paste commands to run Qwen3.5 4B on your machine.
Run
lms load hf-unsloth--qwen3-5-4b-gguf && lms server startYes, Mac Studio M1 Ultra 128GB can run Qwen3.5 4B with a C grade (Runs well). Expected decode speed: 56.0 tok/s.
Qwen3.5 4B (4B parameters) requires approximately 17.6 GB of memory with Q4_K_M quantization.
The recommended quantization for Qwen3.5 4B is Q4_K_M, which balances quality and memory efficiency.
On Mac Studio M1 Ultra 128GB, Qwen3.5 4B achieves approximately 56.0 tokens per second decode speed with a time-to-first-token of 3457ms using Q4_K_M quantization.
For coding workloads, Qwen3.5 4B on Mac Studio M1 Ultra 128GB receives a C grade with 56.0 tok/s and 2.6M context.
On Mac Studio M1 Ultra 128GB, Qwen3.5 4B can safely use up to 2.6M tokens of context. The model's official context limit is —, but available memory constrains the safe maximum.
Not always. Mac Studio M1 Ultra 128GB 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.
Paste this snippet into any page to show a live fit card.
<iframe src="https://willitrunai.com/embed/hf-unsloth--qwen3-5-4b-gguf-on-m1-ultra-128gb" width="400" height="180" frameborder="0" style="border:none;border-radius:12px;overflow:hidden;" title="Will It Run AI — fit result"></iframe>
Preview: