OpenAI LLM Big Closed weights

GPT-5.1

364 days since OpenAI announced it · 13 Nov 2025

GPT-5.1 is a closed-weights LLM from OpenAI, announced 13 Nov 2025. It costs $1.25 per 1M input tokens and $10 per 1M output tokens. Its context window is 400K tokens.

Input: $1.25; per 1M tokens
Cache write: —; per 1M tokens
Cache read: $0.12; per 1M tokens
Output: $10; per 1M tokens
Context window: 400K; tokens
Parameters: —; not disclosed

Announcement: openai.com/index/gpt-5-1
Docs: developers.openai.com/api/docs/models/gpt-5.1

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OpenAI · Big

closed weights

A new one every ~66 days — due now.

GPT-6 Astra +133d 3 Sep 2026
GPT-5.5 +49d 23 Apr 2026
GPT-5.4 +84d 5 Mar 2026
GPT-5.2 +28d 11 Dec 2025
GPT-5.1 +98d 13 Nov 2025
GPT-5 7 Aug 2025