Gemini 3.1 Pro vs GPT-5.5 Instant
Gemini 3.1 Pro 
GPT-5.5 Instant Verdict
- Gemini 3.1 Pro leads on quality: 64.0 vs 60.5.
- Gemini 3.1 Pro is stronger in composite, long context, maths, multimodal, reasoning.
- GPT-5.5 Instant is stronger in agents & tools, coding, human preference, instruction following, knowledge.
- Gemini 3.1 Pro is 2.5× cheaper ($4.50 vs $11.25 per 1M blended).
| Metric | Gemini 3.1 Pro | GPT-5.5 Instant |
|---|---|---|
| BenchLeader Index | 64.0 | 60.5 |
| Agents & tools score | 63.7 | 70.7 |
| Coding score | 59.9 | 61.1 |
| Composite score | 67.4 | 62.9 |
| Human preference score | 59.9 | 67.5 |
| Instruction following score | 69.6 | 69.8 |
| Knowledge score | 66.2 | 69.4 |
| Long context score | 67.6 | 61.4 |
| Maths score | 60.7 | 42.5 |
| Multimodal score | 66.2 | 59.7 |
| Reasoning score | 69.8 | 62.6 |
| Blended price $/M | $4.50 | $11.25 |
| Output speed | 108 tok/s | 129 tok/s |
| Time to first answer | 30.5 s | 16.8 s |
| Context window | 1.0M | 400k |
| GPQA Diamond | 94.1% | 82.5% |
| FrontierMath Tiers 1–3 | 59.6% | 26.3% |
| FrontierMath Tier 4 | 26.8% | 2.4% |
| OTIS Mock AIME | 95.6% | 68.1% |
| Humanity's Last Exam | 46.4% | – |
| Terminal-Bench | 80.2% | – |
| SimpleBench | 79.6% | – |
| SciCode | 58.9% | 48.6% |
| WeirdML | 72.1% | – |
| APEX-Agents | 33.5% | – |
| ProofBench | 26.0% | – |
| GSO-Bench | 22.6% | – |
| Epoch Capabilities Index | 155 | 142.5 |
| LMArena Text | 1487 | 1474 |
| LMArena Hard Prompts | 1507 | 1491 |
| LMArena Coding | 1521 | 1514 |
| LMArena WebDev | 1447 | – |
| LMArena Vision | 1295 | 1251 |
| LMArena Agent | -5.3 | – |
| AA Intelligence Index | 30.4 | 26.8 |
| IFBench | 77.1% | 71.5% |
| AA-LCR | 82.0% | 70.0% |
| MMMU-Pro | 82.4% | – |
| AA-Omniscience | 31.9 | 11.2 |
| Terminal-Bench Hard | 53.8% | 42.4% |
| GPQA Diamond (AA) | 94.1% | 84.7% |
| Humanity's Last Exam (AA) | 47.0% | 21.6% |
| SciCode (AA) | 58.7% | 52.5% |
| τ²-Bench Telecom (AA) | 95.6% | 49.4% |
| AIME 2026 | 98.3% | – |
| HMMT February 2026 | 94.7% | – |
| MathArena Apex | 60.9% | – |
| MultiChallenge | 71.4% | – |
| PRBench Finance | 41.9% | – |
| PRBench Legal | 44.0% | – |
| MultiNRC | 64.7% | – |
| HiL-Bench | 35.3% | – |
| TutorBench | 53.0% | – |
| EQ-Bench 4 | 1142 | – |
| ARC-AGI-1 | 98.0% | – |
| ARC-AGI-2 | 77.1% | – |
| ARC-AGI-3 | 0.4% | – |
Data as of 2026-09-10. Best configuration of each model; every score links to its source on the model pages.
Gemini 3.1 Pro vs GPT-5.5 Instant: questions
- Is Gemini 3.1 Pro better than GPT-5.5 Instant?
- Gemini 3.1 Pro leads on quality: 64.0 vs 60.5. The BenchLeader Index combines every independent quality benchmark; Gemini 3.1 Pro is ahead overall as of 2026-09-10, but check the category scores for your use.
- Is Gemini 3.1 Pro better than GPT-5.5 Instant for coding?
- GPT-5.5 Instant scores higher in coding (61 vs 60 on the category index, where 50 is average).
- Is Gemini 3.1 Pro better than GPT-5.5 Instant for agentic tasks?
- GPT-5.5 Instant scores higher in agentic tasks (71 vs 64 on the category index, where 50 is average).
- Which is cheaper, Gemini 3.1 Pro or GPT-5.5 Instant?
- Gemini 3.1 Pro is cheaper: $4.50 against $11.25 per million tokens, blended at three input tokens per output token.
- Which is faster, Gemini 3.1 Pro or GPT-5.5 Instant?
- GPT-5.5 Instant streams faster: 129 against 108 output tokens per second.
- Which has the larger context window?
- Gemini 3.1 Pro accepts more context: 1.0M against 400k tokens.