Qwen 3 4B VRAM Requirements
Qwen 3 4B needs about 4.2 GB of VRAM at Q4_K_M with an 8K context: 2.3 GB for weights, 1.1 GB for the KV cache and 0.8 GB of runtime overhead. At Q8_0 it needs 5.9 GB and at full FP16 precision 9.4 GB. The smallest GPU that runs it fully is the RTX 3050 8GB.
4.2 GB VRAM
Qwen 3 4B at Q4_K_M with 8K context and the KV cache in FP16.
- Weights 2.3 GB
- KV cache 1.1 GB
- Runtime overhead 0.8 GB
Which GPUs can run it
- RTX 3060 12GBFits~75 tok/s
- RTX 4060 Ti 16GBFits~60 tok/s
- RTX 3090 24GBFits~187 tok/s
- Radeon RX 7900 XTX 24GBFits~163 tok/s
- RTX 4090 24GBFits~200 tok/s
- RTX 5090 32GBFits~337 tok/s
- RTX 6000 Ada 48GBFits~191 tok/s
- A100 80GBFits~377 tok/s
- H100 80GB SXMFits~569 tok/s
- Ryzen AI Max+ 395 128GBFits~50 tok/s
- Apple M4 Max 128GBFits~112 tok/s
- Apple M5 Max 128GBFits~125 tok/s
- RTX PRO 6000 Blackwell 96GBFits~337 tok/s
- NVIDIA DGX Spark 128GBFits~53 tok/s
- Apple M3 Ultra 512GBFits~165 tok/s
Qwen 3 4B VRAM by quantization
Total memory with an FP16 KV cache. "Smallest tier" is the smallest standard VRAM size with a 6% safety margin at 8K.
| Quantization | Bits/weight | Weights | Total at 8K | Total at 32K | Smallest tier |
|---|---|---|---|---|---|
| Q4_K_M | 4.85 | 2.3 GB | 4.2 GB | 7.6 GB | 6 GB |
| Q5_K_M | 5.69 | 2.7 GB | 4.6 GB | 8.0 GB | 6 GB |
| Q6_K | 6.59 | 3.1 GB | 5.0 GB | 8.4 GB | 6 GB |
| Q8_0 | 8.50 | 4.0 GB | 5.9 GB | 9.3 GB | 8 GB |
| FP16 / BF16 | 16.00 | 7.5 GB | 9.4 GB | 12.8 GB | 12 GB |
| Q3_K_M | 3.91 | 1.8 GB | 3.8 GB | 7.2 GB | 6 GB |
| Q2_K | 3.00 | 1.4 GB | 3.4 GB | 6.7 GB | 4 GB |
VRAM by context length
At Q4_K_M. The KV cache grows linearly with context: 0.14 GB per 1,000 tokens in FP16.
| Context | KV cache (FP16) | KV cache (Q8_0) | Total, FP16 cache | Total, Q8_0 cache |
|---|---|---|---|---|
| 4K tokens | 0.6 GB | 0.3 GB | 3.7 GB | 3.4 GB |
| 8K tokens | 1.1 GB | 0.6 GB | 4.2 GB | 3.7 GB |
| 32K tokens | 4.5 GB | 2.4 GB | 7.6 GB | 5.5 GB |
| 40K tokens | 5.6 GB | 3.0 GB | 8.7 GB | 6.1 GB |
GPUs that can run Qwen 3 4B
At Q4_K_M with 8K context. "Best quant" is the highest-quality format that fits fully; "max context" is at Q4_K_M.
| GPU | Usable memory | Status | Best quant | Max context | Speed |
|---|---|---|---|---|---|
| RTX 3050 8GB | 8.0 GB | Fits | Q8_0 | 31K | ~47 tok/s |
| RTX 4060 8GB | 8.0 GB | Fits | Q8_0 | 31K | ~57 tok/s |
| RTX 4060 Ti 8GB | 8.0 GB | Fits | Q8_0 | 31K | ~60 tok/s |
| Radeon RX 7600 8GB | 8.0 GB | Fits | Q8_0 | 31K | ~51 tok/s |
| RTX 3060 Ti 8GB | 8.0 GB | Fits | Q8_0 | 31K | ~93 tok/s |
| RTX 3070 8GB | 8.0 GB | Fits | Q8_0 | 31K | ~93 tok/s |
| RTX 5060 8GB | 8.0 GB | Fits | Q8_0 | 31K | ~93 tok/s |
| RTX 5060 Ti 8GB | 8.0 GB | Fits | Q8_0 | 31K | ~93 tok/s |
| RTX 3070 Ti 8GB | 8.0 GB | Fits | Q8_0 | 31K | ~124 tok/s |
| Intel Arc B570 10GB | 10.0 GB | Fits | Q8_0 | 40K | ~61 tok/s |
| RTX 3080 10GB | 10.0 GB | Fits | Q8_0 | 40K | ~153 tok/s |
| Apple M4 16GB | 10.7 GB | Fits | FP16 / BF16 | 40K | ~25 tok/s |
| RTX 2080 Ti 11GB | 11.0 GB | Fits | FP16 / BF16 | 40K | ~126 tok/s |
| RTX 2060 12GB | 12.0 GB | Fits | FP16 / BF16 | 40K | ~70 tok/s |
About Qwen 3 4B
A small hybrid thinking model. It has 36 layers, more than most 4B models, so its KV cache (144 KB per token in FP16) is larger than Llama 3.1 8B's. Reasoning traces run to thousands of tokens, so give it more context than a chat model needs.
| Spec | Value |
|---|---|
| Parameters | 4.02B |
| Layers | 36 |
| Hidden size | 2560 |
| Attention heads / KV heads | 32 / 8 |
| Head dimension | 128 |
| Vocabulary | 151,936 |
| Max context (used here) | 40K tokens |
| KV cache per token (FP16) | 144 KB |
| Released | 2025-04 |
| License | Apache 2.0 |
Qwen 3 4B VRAM: common questions
Why does Qwen 3 4B use so much memory for context?
It is deep (36 layers) with 8 KV heads of 128 dimensions. That gives 144 KB per token in FP16, so 32K of context adds about 4.5 GB.
How much VRAM does Qwen 3 4B need?
About 4.2 GB at Q4_K_M with an 8K context, 5.9 GB at Q8_0 and 9.4 GB at FP16. Longer contexts add 0.14 GB per 1,000 tokens with an FP16 cache.
What is the cheapest GPU that can run Qwen 3 4B?
The smallest listed device that fits it fully at Q4_K_M with 8K context is the RTX 3050 8GB (8.0 GB usable).