How much VRAM does Qwen3.5 4B need?

Qwen3.5 4B (4B parameters) requires approximately 6.4 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, RTX 4000 Ada 20GB can run Qwen3.5 4B with a C grade (Runs well). Expected decode speed: 106.2 tok/s.

CUsable

Runs well

Using Q4_K_M in Ollama

Capabilities:

Fit status

Runs well

Decode

106.2 tok/s

TTFT

1822 ms

Safe context

50K

Memory

6.4 GB / 20.0 GB

Weights2.4 GB

KV Cache0.8 GB

Runtime1.2 GB

Headroom2.0 GB

Workload	Grade	Fit	Decode	TTFT	Context
Agentic Coding	C	Runs well	106.2 tok/s	2651 ms	93K
Chat	C	Runs well	106.2 tok/s	994 ms	25K
Coding	C	Runs well	106.2 tok/s	1822 ms	50K
RAG	C	Runs well	106.2 tok/s	3314 ms	93K
Reasoning	C	Runs well	106.2 tok/s	2154 ms	50K

How Qwen3.5 4B (4B params) fits at each quantization level on RTX 4000 Ada 20GB (20.0 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	1.6 GB	Low	D31
Q3_K_S	3	2.0 GB	Low	D32
NVFP4	4

Upgrade options

MacBook Pro M2 Max 32GBBudget pick

C95.1 tok/s decode

~$1,999 MSRP

MacBook Pro M1 Max 32GBBest value

C90.2 tok/s decode

~$2,499 MSRP