DeepSeek V4.1 Flash vs GPT-5.5 Pro
DeepSeek V4.1 Flash 
GPT-5.5 Pro Verdict
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 61.9.
- DeepSeek V4.1 Flash (max) is stronger in agents & tools, coding, composite, knowledge, long context, multimodal.
- GPT-5.5 Pro (xhigh) is stronger in reasoning, maths.
- DeepSeek V4.1 Flash (max) is 258× cheaper ($0.262 vs $67.50 per 1M blended).
- DeepSeek V4.1 Flash (max) streams 53.7× faster (215 vs 4 tokens per second).
| Metric | DeepSeek V4.1 Flash (max) | GPT-5.5 Pro (xhigh) |
|---|---|---|
| BenchLeader Index | 61.9 | 67.1 |
| Agents & tools score | 59.6 | – |
| Coding score | 68.9 | – |
| Composite score | 74.5 | – |
| Knowledge score | 61.7 | – |
| Long context score | 68.5 | – |
| Multimodal score | 61.4 | – |
| Reasoning score | 69.5 | 80.1 |
| Maths score | – | 74.5 |
| Blended price $/M | $0.262 | $67.50 |
| Output speed | 215 tok/s | 4 tok/s |
| Time to first answer | 10.5 s | 3.5 s |
| Context window | 1M | 1.1M |
| FrontierMath Tiers 1–3 | – | 87.7% |
| FrontierMath Tier 4 | – | 78.0% |
| LMArena WebDev | 1614 | – |
| LMArena Agent | 4.9 | – |
| LiveBench | 81.1% | – |
| LiveBench Reasoning | 86.7% | – |
| LiveBench Coding | 80.0% | – |
| LiveBench Agentic Coding | 77.3% | – |
| LiveBench Mathematics | 93.3% | – |
| LiveBench Data Analysis | 79.3% | – |
| LiveBench Language | 81.2% | – |
| LiveBench Instruction Following | 70.0% | – |
| AA Intelligence Index | 39.5 | – |
| AA-LCR | 84.0% | – |
| MMMU-Pro | 77.0% | – |
| AA-Omniscience | -5.3 | – |
| Humanity's Last Exam (AA) | 39.3% | – |
| SciCode (AA) | 51.9% | – |
| ARC-AGI-1 | – | 95.0% |
| ARC-AGI-2 | – | 84.2% |
| CritPt | 14.3% | 30.6% |
| GDPval (AA) | 56.6% | – |
| LMCA | – | 53.9% |
| DTBench | – | 96.0% |
Data as of 2026-09-19. Best configuration of each model; every score links to its source on the model pages.
DeepSeek V4.1 Flash vs GPT-5.5 Pro: questions
- Is DeepSeek V4.1 Flash better than GPT-5.5 Pro?
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 61.9. The BenchLeader Index combines every independent quality benchmark; GPT-5.5 Pro (xhigh) is ahead overall as of 2026-09-19, but check the category scores for your use.
- Which is cheaper, DeepSeek V4.1 Flash or GPT-5.5 Pro?
- DeepSeek V4.1 Flash is cheaper: $0.262 against $67.50 per million tokens, blended at three input tokens per output token.
- Which is faster, DeepSeek V4.1 Flash or GPT-5.5 Pro?
- DeepSeek V4.1 Flash streams faster: 215 against 4 output tokens per second.
- Which has the larger context window?
- GPT-5.5 Pro accepts more context: 1.1M against 1M tokens.