How much VRAM does Qwen3.5 4B need?
Qwen3.5 4B needs 2.6 GB for its weights at 4-bit, 3.9 GB with an 8K context and 4.7 GB with 32K. At 8-bit, 5.9 GB.
- Parameters
- 4.7B
- Longest context
- 256K
- Released
- Feb 2026
- License
- Apache 2.0
- Strongest at
- Agents, Docs
Memory at each precision
| Precision | Weights | With 8K | With 32K | With 128K |
|---|---|---|---|---|
| 16-bit | 8.7 GB | 10.0 GB | 10.7 GB | 13.7 GB |
| 8-bit | 4.6 GB | 5.9 GB | 6.7 GB | 9.7 GB |
| 6-bit | 3.6 GB | 4.9 GB | 5.6 GB | 8.6 GB |
| 5-bit | 3.1 GB | 4.4 GB | 5.1 GB | 8.1 GB |
| 4-bit | 2.6 GB | 3.9 GB | 4.7 GB | 7.7 GB |
| 3-bit | 2.1 GB | 3.4 GB | 4.2 GB | 7.2 GB |
| 2-bit | 1.6 GB | 2.9 GB | 3.7 GB | 6.7 GB |
| 1.6-bit | 917 MB | 2.2 GB | 2.9 GB | 5.9 GB |
One conversation, 16-bit context cache, runtime overhead included.
What runs it
| Machine | Best fit | Context | Speed | First reply |
|---|---|---|---|---|
| RTX 3060 12 GB | 8-bit | 176K | 48 tok/s | 0.7 s |
| RTX 4060 Ti 16 GB | 8-bit | 256K | 39 tok/s | 0.4 s |
| RTX 3090 | 8-bit | 256K | 116 tok/s | 0.3 s |
| RTX 4090 | 8-bit | 256K | 124 tok/s | 0.1 s |
| RTX 5090 | 8-bit | 256K | 202 tok/s | 0.1 s |
| 2× RTX 3090 | 8-bit | 256K | 116 tok/s | 0.1 s |
| RTX PRO 6000 Blackwell | 8-bit | 256K | 202 tok/s | 0.1 s |
| M4 Max 128 GB | 8-bit | 256K | 60 tok/s | 1.4 s |
| M5 Max 128 GB | 8-bit | 256K | 66 tok/s | 0.4 s |
| Ryzen AI Max+ 395 128 GB | 8-bit | 256K | 29 tok/s | 0.8 s |
| DGX Spark 128 GB | 8-bit | 256K | 37 tok/s | 0.3 s |
| M3 Ultra 256 GB | 8-bit | 256K | 84 tok/s | 0.8 s |
| M5 Ultra 512 GB | 8-bit | 256K | 111 tok/s | 0.3 s |
| H100 SXM | 8-bit | 256K | 323 tok/s | 0.1 s |
| DGX Station GB300 | 8-bit | 256K | 508 tok/s | 0.1 s |
| 8× H200 NVL | 8-bit | 256K | 408 tok/s | 0.1 s |
Best fit is the highest quality, up to 8-bit, that leaves 16K of context. First reply is the wait for a 2K prompt. Speeds are rough, plus or minus 25%.
How to run it
- Ollama
ollama run qwen3.5:4b- llama.cpp
llama-server -hf unsloth/Qwen3.5-4B-GGUF- vLLM
vllm serve Qwen/Qwen3.5-4B- MLX (Mac)
mlx_lm.chat --model mlx-community/Qwen3.5-4B-MLX-4bit
Questions
How much VRAM does Qwen3.5 4B need?
Qwen3.5 4B needs 2.6 GB for its weights at 4-bit, 3.9 GB with an 8K context and 4.7 GB with 32K. At 8-bit, 5.9 GB.
Can Qwen3.5 4B run on an RTX 4090?
Yes. At 8-bit it holds 256K of context and writes about 124 tokens a second.