What GPU do I need to run Qwen/Qwen3.5-4B-Base?
4.7B parameters, published in BF16. View on Hugging Face
Set up Qwen3.5-4B-BaseQwen3.5-4B-Base is published by Qwen on Hugging Face, with 442,201 downloads and 85 likes to date. It's a Qwen3_5ForConditionalGeneration model built for image-text-to-text, published natively in BF16.
VRAM required & cheapest live GPU fit
Required VRAM = weight size at each precision times a flat 1.2 overhead for activations and fragmentation. The KV-cache grows with context and is not in that factor; it is listed per model below where the architecture is published. Full formula and assumptions: methodology.
| Precision | Weight size | Required VRAM | Cheapest live fit | GPUs needed | Est. $/hr (full fit) |
|---|---|---|---|---|---|
| BF16 | 8.7 GB | 10.4 GB | RTX 3060 | 1 | $0.110/hr |
| FP8 (quantized) | 4.3 GB | 5.2 GB | RTX 4070 Super | 1 | $0.121/hr |
| INT4 (quantized) | 2.2 GB | 2.6 GB | RTX 3060 | 1 | $0.110/hr |
A GPU is only matched to a row if its hardware supports that precision, and the primary recommendation is always a single-GPU fit when one exists.
INT4 requires a quantized checkpoint actually published for this model, check its Hugging Face page before relying on this row.
Cheapest way to run Qwen3.5-4B-Base at its published (BF16) precision: 1× RTX 3060, at $0.110/hr per GPU ($0.110/hr total). Quantizing to FP8 or INT4 (rows above) can cost less, but requires a compatible quantized checkpoint to exist for this model.
Qwen3.5-4B-Base: KV cache by context length
The KV cache is the memory the attention layers hold for every token of context, on top of the weights. It is not part of the flat 1.2x overhead in the table above, grows with context length and with every concurrent request, and is why a long-context deployment needs more VRAM than the table shows.
Hybrid: only the full-attention layers cache per token; the other layers keep a fixed-size state. Cached per token: 32,768 bytes at 16-bit.
| Context | KV cache, one sequence |
|---|---|
| 4K | 0.13 GB |
| 32K | 1.0 GB |
| 128K | 4.0 GB |
| 256K (model maximum) | 8.0 GB |
Computed from the layer, head and window counts in the model's own configuration (Qwen/Qwen3.5-4B-Base), at 16 bits per cached value. Each concurrent sequence needs its own cache, on top of the weights.
Qwen3.5-4B-Base: common questions
Does Qwen3.5-4B-Base fit on a 12 GB GPU?
Yes. At BF16 it needs 10.4 GB of VRAM, so a 12 GB card holds it with 1.6 GB to spare. An 8 GB card is not enough for it at BF16.
What is the least VRAM Qwen3.5-4B-Base can run in?
2.6 GB, at INT4 (quantized), which fits a 6 GB card, against 10.4 GB at BF16. That row assumes an INT4 checkpoint has actually been published for this model, so check its Hugging Face page before planning around it.
Weight-to-VRAM math, the fit rules, and how live prices are normalized: full methodology.
More Qwen3.5 models
- Qwen3.5-4B (4.7B, BF16)
- Qwen3.5-4B-AWQ (4.7B, BF16)
- Qwen3.8-4B-Distill (4.7B, BF16)
- NuExtract3 (4.5B, BF16)
- CogEvol-4B (4.5B, BF16)
Lineage
Quantized and fine-tuned versions
Alternatives at this size
Other models for image-text-to-text within about a third of Qwen3.5-4B-Base's 4.7B parameters, from other model lines.
- Unlimited-OCR (3.3B, BF16)
- chandra-ocr-2 (5.3B, BF16)
- DeepSeek-OCR (3.3B, BF16)
- gemma-3-4b-it (4.3B, BF16)
- Phi-3.5-vision-instruct (4.1B, BF16)
More on Qwen3.5-4B-Base
Fits on a 12 GB GPU at BF16: every model that fits in 12 GB.
Fits on an 8 GB GPU at FP8: every model that fits in 8 GB.
Best vision-language models: how Qwen3.5-4B-Base ranks against the rest.
Related reading: H100 pricing and specs, How much VRAM you need for LLMs, Serving LLMs with vLLM, vLLM vs TensorRT-LLM vs SGLang, and Best GPU for LLM inference.
