Qwen3.5 4B Safety Thinking vs Qwen3 4B Thinking 2507
Side-by-side comparison of VRAM requirements, quantization, context length, and hardware compatibility.
Specifications
| Qwen3.5 4B Safety Thinking | Qwen3 4B Thinking 2507 | |
|---|---|---|
| Parameters | 4.2B | 4.0B |
| Context | 262K | 262K |
| Architecture | Qwen3_5ForConditionalGeneration | Qwen3ForCausalLM |
| License | Apache 2.0 | Apache 2.0 |
| Downloads | 2.8K | 602.5K |
| Released | Mar 2026 | Aug 2025 |
VRAM by Quantization: Qwen3.5 4B Safety Thinking vs Qwen3 4B Thinking 2507
| Quantization | Bits | Qwen3.5 4B Safety Thinking VRAM | Qwen3 4B Thinking 2507 VRAM |
|---|---|---|---|
| Q2_K | 3.40 | 2.3 GB | 2.2 GB |
| Q3_K_M | 3.90 | 2.5 GB | 2.5 GB |
| Q3_K_S | 3.50 | 2.3 GB | 2.3 GB |
| Q4_0 | 4.00 | — | 2.5 GB |
| Q4_K_M | 4.80 | 3.0 GB | 2.9 GB |
| Q5_K_M | 5.70 | 3.5 GB | 3.4 GB |
| Q6_K | 6.60 | 3.9 GB | 3.8 GB |
| Q8_0 | 8.00 | 4.7 GB | 4.5 GB |
Verdict
Qwen3 4B Thinking 2507 needs less VRAM at Q4_K_M (2.9 GB vs 3.0 GB), so it fits on smaller GPUs. Qwen3 4B Thinking 2507 is the more widely downloaded of the two.
Frequently Asked Questions
- Which needs less VRAM, Qwen3.5 4B Safety Thinking or Qwen3 4B Thinking 2507?
At Q4_K_M, Qwen3.5 4B Safety Thinking needs 3.0 GB and Qwen3 4B Thinking 2507 needs 2.9 GB, so Qwen3 4B Thinking 2507 is the lighter option to run locally.
- Which has a longer context window, Qwen3.5 4B Safety Thinking or Qwen3 4B Thinking 2507?
Qwen3.5 4B Safety Thinking supports 262,144 tokens and Qwen3 4B Thinking 2507 supports 262,144 tokens.
- What is the difference between Qwen3.5 4B Safety Thinking and Qwen3 4B Thinking 2507?
Qwen3.5 4B Safety Thinking is a 4.2B model from MerlinSafety (Qwen family), while Qwen3 4B Thinking 2507 is a 4.0B model from Alibaba (Qwen family). Compare their VRAM requirements above to see which fits your GPU or Mac.