Gemini 3.8 Flash vs GPT-5.5 Pro
Gemini 3.8 Flash 
GPT-5.5 Pro Verdict
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 64.9.
- Gemini 3.8 Flash (medium) is stronger in agents & tools, coding, composite, knowledge, long context, multimodal.
- GPT-5.5 Pro (xhigh) is stronger in reasoning, maths.
- Gemini 3.8 Flash (medium) is 45× cheaper ($1.50 vs $67.50 per 1M blended).
- Gemini 3.8 Flash (medium) streams 19.5× faster (78 vs 4 tokens per second).
| Metric | Gemini 3.8 Flash (medium) | GPT-5.5 Pro (xhigh) |
|---|---|---|
| BenchLeader Index | 64.9 | 67.1 |
| Agents & tools score | 74.8 | – |
| Coding score | 63.8 | – |
| Composite score | 79.7 | – |
| Knowledge score | 77.8 | – |
| Long context score | 68.5 | – |
| Multimodal score | 68.9 | – |
| Reasoning score | 65.6 | 80.1 |
| Maths score | – | 74.5 |
| Blended price $/M | $1.50 | $67.50 |
| Output speed | 78 tok/s | 4 tok/s |
| Time to first answer | 2.3 s | 3.5 s |
| Context window | 1.0M | 1.1M |
| FrontierMath Tiers 1–3 | – | 87.7% |
| FrontierMath Tier 4 | – | 78.0% |
| SciCode | 54.4% | – |
| AA Intelligence Index | 40 | – |
| AA-LCR | 84.0% | – |
| MMMU-Pro | 84.2% | – |
| AA-Omniscience | 28.6 | – |
| GPQA Diamond (AA) | 93.5% | – |
| Humanity's Last Exam (AA) | 42.1% | – |
| SciCode (AA) | 55.1% | – |
| ARC-AGI-1 | – | 95.0% |
| ARC-AGI-2 | – | 84.2% |
| CritPt | 12.3% | 30.6% |
| GDPval (AA) | 47.8% | – |
| τ²-Bench Banking (AA) | 45.8% | – |
| DeepSWE | 71.0% | – |
| LMCA | – | 53.9% |
| DTBench | – | 96.0% |
| CursorBench | 67.0% | – |
Data as of 2026-09-19. Best configuration of each model; every score links to its source on the model pages.
Gemini 3.8 Flash vs GPT-5.5 Pro: questions
- Is Gemini 3.8 Flash better than GPT-5.5 Pro?
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 64.9. 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, Gemini 3.8 Flash or GPT-5.5 Pro?
- Gemini 3.8 Flash is cheaper: $1.50 against $67.50 per million tokens, blended at three input tokens per output token.
- Which is faster, Gemini 3.8 Flash or GPT-5.5 Pro?
- Gemini 3.8 Flash streams faster: 78 against 4 output tokens per second.
- Which has the larger context window?
- GPT-5.5 Pro accepts more context: 1.1M against 1.0M tokens.