GPT-5.5 vs Gemini 3.1 Pro — OpenAI against Google at the very top of the 2026 leaderboard. Below is the full side-by-side: specifications, API pricing, context window, local hardware requirements, and a clear, data-driven recommendation on which to pick.
| Spec | GPT-5.5 | Gemini 3.1 Pro |
|---|---|---|
| Developer | OpenAI | |
| Type | LLM (reasoning) | LLM (multimodal) |
| Parameters | Undisclosed | Undisclosed |
| Context window | 1.05M | 1.05M |
| Modality | Text, Vision → Text | Text, Image, Audio, Video → Text |
| License | Proprietary | Proprietary |
| Open weights | ❌ No | ❌ No |
| Input price ($/1M) | $5.00 | $2.00 |
| Output price ($/1M) | $30.00 | $12.00 |
| VRAM (4-bit) | — | — |
| Min GPU (local) | — | — |
| Released | 2026 | 2026 |
Key differences
- Cost: Gemini 3.1 Pro is 150% cheaper than GPT-5.5 on a blended-token basis.
- Openness: both are proprietary, API-only models — no self-hosting option for either.
Which should you choose?
Choose GPT-5.5 if it fits your existing stack or you prefer OpenAI.
Choose Gemini 3.1 Pro if you want the lower per-token cost for high-volume workloads.
→ Estimate real costs in the API cost calculator · check local hardware in the VRAM calculator · browse all 30+ models.
All specs and prices are pulled live from our AI models database and kept current. Compare either model against others, or estimate your own monthly spend with the free calculators above.