GPT-5.1 Codex Max is the newer model, released after GPT-3.5 Turbo.
| Spec | GPT-3.5 Turbo | GPT-5.1 Codex Max |
|---|---|---|
| Input price | $1.5/M tokens | — |
| Output price | $2/M tokens | — |
| Context window | 16K tokens | — |
| Weights | Closed | Closed |
| Free API (OpenRouter) | No | No |
| Released | Mar 2022 | Dec 2025 |
Not enough votes to call it. On the specs, GPT-5.1 Codex Max has the edge: bigger model tier, newer.
Per million tokens. Prices and uptime via OpenRouter, checked 9 Sep 2026.
GPT-5.1 Codex Max uses 12.3x more headings