How much VRAM does Qwen3.5 4B need?

Qwen3.5 4B (4B parameters) requires approximately 6.0 GB of memory with Q4_K_M quantization.

What is the best quantization for Qwen3.5 4B?

The recommended quantization for Qwen3.5 4B is Q4_K_M, which balances quality and memory efficiency.

Can it run?

Yes, RX 6800 16GB can run Qwen3.5 4B with a C grade (Runs well). Expected decode speed: 151.1 tok/s.

CUsable

Runs well

Using Q4_K_M in Ollama

Capabilities:

Fit status

Runs well

Decode

151.1 tok/s

TTFT

1281 ms

Safe context

42K

Memory

6.0 GB / 16.0 GB

Weights2.4 GB

KV Cache0.8 GB

Runtime1.2 GB

Headroom1.6 GB

Workload	Grade	Fit	Decode	TTFT	Context
Agentic Coding	C	Runs well	115.4 tok/s	2440 ms	79K
Chat	C	Runs well	115.4 tok/s	915 ms	21K
Coding	C	Runs well	151.1 tok/s	1281 ms	42K
RAG	C	Runs well	115.4 tok/s	3050 ms	79K
Reasoning	C	Runs well	115.4 tok/s	1982 ms	42K

How Qwen3.5 4B (4B params) fits at each quantization level on RX 6800 16GB (16.0 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	1.6 GB	Low	D32
Q3_K_S	3	2.0 GB	Low	D32
NVFP4	4

Upgrade options

MacBook Pro M4 Pro 24GBBudget pick

C86.2 tok/s decode

~$1,999 MSRP