OpenAI · OpenAI (GPT / ChatGPT)
GPT-5.5 Pro
ActiveMaximum-reasoning-depth variant of GPT-5.5 for research-grade problems ($30/$180 per 1M).
About this version
GPT‑5.5 Pro is an active, reasoning‑tier model in the ChatGPT family released on 23 April 2026 with a knowledge cutoff of January 2026 and a one‑million‑token context window. It is presented as the maximum‑reasoning‑depth variant of GPT‑5.5, positioned for research‑grade problems and priced at $30 (or $180) per million tokens.
- API string
- gpt-5.5-pro
- Context window
- 1M ctx
- Knowledge cutoff
- Jan 1, 2026
- Tier
- Reasoning
- Released
- Apr 23, 2026
Release & change timeline
1 event- Release
GPT-5.5 Pro released
Maximum-reasoning-depth variant at $30/$180 per 1M tokens.
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