GPT-5.5 — Specifications
| Developer | OpenAI |
|---|---|
| Type | LLM (reasoning) |
| Modality | Text, Vision → Text |
| Parameters | Undisclosed |
| Context window | 1.05M |
| Max output | 128K |
| License | Proprietary |
| Open weights | ❌ No |
| Released | 2026 |
| Input price | $5.00 /1M |
| Output price | $30.00 /1M |
| API providers | OpenAI, Azure |
OpenAI’s flagship model — frontier reasoning across coding, writing, research and multimodal tasks, with a ~1.05M-token context window. Prompts above 272K input tokens are billed at a higher rate; a GPT-5.5 Pro tier targets the highest-stakes reasoning.