Gemini 3.5 Flash vs GPT-5 Pro
Gemini 3.5 Flash 
GPT-5 Pro Verdict
- Gemini 3.5 Flash (medium) leads on quality: 64.1 vs 60.8.
- Gemini 3.5 Flash (medium) is stronger in agents & tools, coding, composite, human preference, instruction following, knowledge, long context, multimodal, reasoning.
- Gemini 3.5 Flash (medium) is 12× cheaper ($3.38 vs $41.25 per 1M blended).
| Metric | Gemini 3.5 Flash (medium) | GPT-5 Pro |
|---|---|---|
| BenchLeader Index | 64.1 | 60.8 |
| Agents & tools score | 68.0 | – |
| Coding score | 58.9 | – |
| Composite score | 71.5 | – |
| Human preference score | 67.8 | – |
| Instruction following score | 72.5 | – |
| Knowledge score | 74.0 | 68.0 |
| Long context score | 63.6 | – |
| Multimodal score | 67.6 | 67.4 |
| Reasoning score | 67.1 | 57.6 |
| Blended price $/M | $3.38 | $41.25 |
| Output speed | 217 tok/s | – |
| Time to first answer | 15.5 s | – |
| Context window | 1M | 400k |
| Humanity's Last Exam | – | 31.6% |
| SimpleBench | – | 61.6% |
| Epoch Capabilities Index | – | 150.3 |
| LMArena Text | 1476 | – |
| LMArena Hard Prompts | 1493 | – |
| LMArena Coding | 1503 | – |
| LMArena WebDev | 1491 | – |
| LMArena Vision | 1306 | – |
| AA Intelligence Index | 33.6 | – |
| IFBench | 74.6% | – |
| AA-LCR | 74.3% | – |
| MMMU-Pro | 83.9% | – |
| AA-Omniscience | 20.8 | – |
| Terminal-Bench Hard | 39.4% | – |
| GPQA Diamond (AA) | 92.1% | – |
| Humanity's Last Exam (AA) | 41.3% | – |
| τ²-Bench Telecom (AA) | 95.6% | – |
| PRBench Finance | – | 51.1% |
| PRBench Legal | – | 49.9% |
| VISTA | – | 52.4% |
| MultiNRC | – | 65.2% |
| Kagi LLM Benchmark | – | 76.8% |
| ARC-AGI-1 | – | 70.2% |
| ARC-AGI-2 | – | 18.3% |
Data as of 2026-09-10. Best configuration of each model; every score links to its source on the model pages.
Gemini 3.5 Flash vs GPT-5 Pro: questions
- Is Gemini 3.5 Flash better than GPT-5 Pro?
- Gemini 3.5 Flash (medium) leads on quality: 64.1 vs 60.8. The BenchLeader Index combines every independent quality benchmark; Gemini 3.5 Flash (medium) is ahead overall as of 2026-09-10, but check the category scores for your use.
- Which is cheaper, Gemini 3.5 Flash or GPT-5 Pro?
- Gemini 3.5 Flash is cheaper: $3.38 against $41.25 per million tokens, blended at three input tokens per output token.
- Which has the larger context window?
- Gemini 3.5 Flash accepts more context: 1M against 400k tokens.