Qwen3.5 4B PTBR — Hardware Requirements & GPU Compatibility
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Qwen3.5 4B PTBR is a 4B-parameter open language model from lucasmg09 in the Qwen 3.5 family. At Q4_K_M it needs about 2.64 GB of VRAM — see which GPUs and Macs can run it below.
Runs great on a 24 GB GPU
Runs from 8 GB (Q4_K_M · 32K)Best on 24 GB (Q4_K_M · ~248 tok/s · 32K)Macs from 8 GB (Q4_K_M · ~27 tok/s)
Apache 2.0
Reference GPU · RTX 4090 24 GB
Estimates, ±20% · how we estimate
Run Qwen3.5 4B PTBR
One recommended way. Every other method, OS and quant is in the step-by-step guide.
Recommended
vllm serve lucasmg09/Qwen3.5-4B-PTBR --max-model-len 16384vLLM repo with its own quantisation
Download: Weights on Hugging Face
Other ways
each opens step-by-stepRun in cloud
Fits on RTX 3060 12GB (7 GB headroom) · Q4_K_M
- Generation speed
- ~89 tok/s
- generation speed
- Cost per 1M output tokens
- $0.22
- per 1M output tokens
How Much VRAM Does Qwen3.5 4B PTBR Need?
Select a quantization level; the listed hardware adheres to it.
| Quantization | VRAM | +32K | On RTX 4090 (reference) | |
|---|---|---|---|---|
| 1.5 GB | 6 GB | 2-bit · i-quant medium — Importance-weighted 2-bit, medium | Fits: 32K context · ~440 tok/s | |
| 1.9 GB | 6.4 GB | 2-bit · K-quant — 2-bit quantization with K-quant improvements | Fits: 32K context · ~350 tok/s | |
| 2.0 GB | 6.5 GB | 3-bit · i-quant medium — Importance-weighted 3-bit, medium | Fits: 32K context · ~331 tok/s | |
| 2.1 GB | 6.7 GB | 3-bit medium — 3-bit medium quantization | Fits: 32K context · ~305 tok/s | |
| 2.5 GB | 7 GB | 4-bit · i-quant non-linear — Importance-weighted 4-bit, non-linear | Fits: 32K context · ~264 tok/s | |
| 2.6 GB | 7.2 GB | 4-bit medium — 4-bit medium quantization — most popular sweet spot | Fits: 32K context · ~248 tok/s | |
| 3.1 GB | 7.7 GB | 5-bit medium — 5-bit medium quantization — good quality/size tradeoff | Fits: 32K context · ~209 tok/s | |
| 3.6 GB | 8.2 GB | 6-bit, very good — 6-bit quantization, very good quality | Fits: 32K context · ~181 tok/s | |
| 4.4 GB | 8.9 GB | 8-bit, near-lossless — 8-bit quantization, near-lossless | Fits: 32K context · ~149 tok/s | |
| 8.8 GB | 13.3 GB | 16-bit · bfloat — Brain floating point 16 — preferred for training | Fits: 32K context · ~75 tok/s |
Selected Q4_K_M
4-bit medium quantization4.8GBat 16K context
- Weights
- 2.0 GB
- KV cache
- 2.4 GB
- Overhead
- 0.3 GB
Fits RTX 4090 (reference) · 19.3 GB free · ~248 tok/s
≥50 tok/s needs ≥203 GB/s · RTX 5090 ~441, RTX 3090 Ti ~248
Which Hardware Can Run Qwen3.5 4B PTBR?
Q4_K_M · 2.6 GBQwen3.5 4B PTBR (Q4_K_M) requires 2.6 GB of VRAM to load the model weights. For comfortable inference with headroom for KV cache and system overhead, 4+ GB is recommended. 52 GPUs can run it, including NVIDIA GeForce RTX 5090, NVIDIA GeForce RTX 3090 Ti. 163 devices with unified memory can run Qwen3.5 4B PTBR, including Mac Studio (M3 Ultra, 256GB), Mac Studio (M3 Ultra, 512GB).
≤ 11 GB
≤ 11 GB tier →fits · 3.3 GB free · up to 32K ctx
16 GPUs · 1 Mac class · 2 device families
RTX 3080~187Simulate output on RTX 3080RTX 2080 Ti~152Simulate output on RTX 2080 TiRTX 3070 Ti~150Simulate output on RTX 3070 TiM3*8 GB~27Simulate output on iMac 24" M3 (8 GB)Orin Nano~25Simulate output on NVIDIA Jetson Orin Nano 8GB (Super)iPhone~18Simulate output on iPhone 1720 GB
fits · 15.3 GB free · up to 32K ctx
1 GPU
RX 7900 XT~182Simulate output on RX 7900 XT32–40 GB
fits · 27.3 GB free · up to 32K ctx
1 GPU · 3 Mac classes · 4 device families
RTX 5090~441Simulate output on RTX 5090M5 Max36 GB~122Simulate output on Mac Studio M5 Max (36 GB)M532 GB~41Simulate output on MacBook Air 13" M5 (32 GB)Orin~50Simulate output on NVIDIA Jetson AGX Orin 32GBSnapdragon X Elite (X1E-80-100)~33Simulate output on Snapdragon X Elite Copilot+ PC
By VRAM tier · typical GPUs and Macs at Q4_K_M
Alternatives to Qwen3.5 4B PTBR
Qwen 3.5 family · 34 models →Similar models
6| Model | Score | VRAM | tok/s | Why it is similar |
|---|---|---|---|---|
| Gemma 3 4B ITGoogle | 64.0 | 5 GB | ~231 | same size |
| Granite Vision 4.1 4BIBM | — | 4 GB | ~228 | same size |
| Qwen3 4B Instruct 2507Alibaba | — | 4.2 GB | ~226 | same size |
| MiniCPM V 4OpenBMB | — | 3.1 GB | ~236 | same size |
| Phi 4 Mini ReasoningMicrosoft | — | 4.8 GB | ~228 | same size |
| Qwen2.5 VL 3B InstructAlibaba | — | 3.2 GB | ~249 | same size |
Specifications
- Publisher
- lucasmg09
- Family
- Qwen 3.5
- Parameters
- 4B
- Release Date
- 2026-05-26
- License
- Apache 2.0
Frequently Asked Questions
How much VRAM does Qwen3.5 4B PTBR need?
Qwen3.5 4B PTBR requires 2.6 GB of VRAM at Q4_K_M, or 8.8 GB at BF16.
VRAM = Weights + KV Cache + Overhead
Weights = 4B × 4.8 bits ÷ 8 = 2.4 GB
KV Cache + Overhead ≈ 0.2 GB (at 2K context + ~0.3 GB framework)
Fit ratings and hardware model lists check this model with room for a 16K-token context, which needs a little more memory.
VRAM usage by quantization
What's the best quantization for Qwen3.5 4B PTBR?
For Qwen3.5 4B PTBR, Q4_K_M (2.6 GB) offers the best balance of quality and VRAM usage. Q5_K_M (3.1 GB) provides better quality if you have the VRAM. The smallest option is IQ2_M at 1.5 GB.
VRAM requirement by quantization
★ Recommended — best balance of quality and VRAM usage.
Can I run Qwen3.5 4B PTBR on a Mac?
Yes — Mac Mini M2 (8 GB) and 145 other Macs can run Qwen3.5 4B PTBR. Apple Silicon uses unified memory, so the model shares RAM with the system. At Q4_K_M you need at least 2.6 GB of usable unified memory (RAM minus macOS overhead).
Can I run Qwen3.5 4B PTBR locally?
Yes — Qwen3.5 4B PTBR can run locally on consumer hardware. Popular tools include Ollama, LM Studio, and llama.cpp.
How fast is Qwen3.5 4B PTBR?
At Q4_K_M, Qwen3.5 4B PTBR can reach ~1818 tok/s on AMD Instinct MI350X. On NVIDIA GeForce RTX 4090: ~248 tok/s. Speed depends mainly on GPU memory bandwidth. Real-world results typically within ±20%.
tok/s = (bandwidth GB/s ÷ model GB) × efficiency
Example: NVIDIA B200 → 8000 ÷ 2.64 × 0.65 = ~1970 tok/s
Estimated speed at Q4_K_M (2.6 GB)
Real-world results typically within ±20%. Speed depends on batch size, quantization kernel, and software stack.
What's the download size of Qwen3.5 4B PTBR?
At Q4_K_M, the download is about 2.40 GB. The full-precision BF16 version is 8.00 GB. The smallest option (IQ2_M) is 1.35 GB.
Which GPUs can run Qwen3.5 4B PTBR?
52 consumer GPUs can run Qwen3.5 4B PTBR at Q4_K_M. Top options include AMD Radeon RX 6700 XT, AMD Radeon RX 6800, AMD Radeon RX 6800 XT. 52 GPUs have plenty of headroom for comfortable inference.
Which devices can run Qwen3.5 4B PTBR?
163 devices with unified memory can run Qwen3.5 4B PTBR at Q4_K_M (2.6 GB), including AMD Ryzen AI 9 HX 370 (Strix Point) Laptop, ASUS Ascent GX10, Beelink GTR9 Pro (Ryzen AI Max+ 395, 128 GB), Framework Desktop (Ryzen AI Max+ 395, 128 GB). Apple Silicon Macs use unified memory shared between CPU and GPU, making them well-suited for local LLM inference.