GPT-5 Nano is the newer model, released after ChatGPT-4o (March 2025).
| Spec | ChatGPT-4o (March 2025) | GPT-5 Nano |
|---|---|---|
| Input price | $5/M tokens | — |
| Output price | $15/M tokens | — |
| Context window | 128K tokens | — |
| Weights | — | Closed |
| Free API (OpenRouter) | No | No |
| Released | Mar 2025 | Aug 2025 |
Not enough votes to call it. On the specs, nothing separates them.
No hosts listed on OpenRouter.
Per million tokens. Prices and uptime via OpenRouter, checked 8 Sep 2026.
ChatGPT-4o (March 2025) uses 329.7x more bold