What the evidence says
- Developer
- OpenAI
- Released
- November 19, 2025
- Domains
- Language
- Tasks
- Language modeling/generation
- Access
- API access
- Weights
- Closed weights
Platform facts
OpenRouter's platform listing, retrieved July 22, 2026. Routed platform prices, not first-party provider prices.
- Input price
- $1.25 per 1M tokens
- Output price
- $10.00 per 1M tokens
- Context length
- 400,000 tokens
- Listed on OpenRouter
- December 4, 2025
Common questions
What is GPT-5.1-Codex-Max?
GPT-5.1-Codex-Max is a OpenAI model released November 19, 2025, according to Epoch AI's reviewed catalog record. The record classifies it under language.
How does GPT-5.1-Codex-Max rank on LMArena?
No board Model Gauntlet mirrors currently lists this exact model revision under a reviewed identity, so no rating is reported here.
What does GPT-5.1-Codex-Max cost?
OpenRouter lists it at $1.25 per million input tokens and $10.00 per million output tokens, retrieved July 22, 2026. Those are the platform's routed prices, not first-party provider prices.