GPT-5.1 is cheaper than GPT-5 Pro at $1.25/M vs $15/M input tokens.
| Spec | GPT-5 Pro | GPT-5.1 |
|---|---|---|
| Input price | $15/M tokens | $1.25/M tokens |
| Output price | $120/M tokens | $10/M tokens |
| Context window | 400K tokens | 400K tokens |
| Weights | Closed | Closed |
| Free API (OpenRouter) | No | No |
| Released | Oct 2025 | Nov 2025 |
| SWE-bench Verified | 74.9% | 76.3% |
Not enough votes to call it. On the specs, nothing separates them.
Pick GPT-5 Pro for Reasoning. Pick GPT-5.1 for Web Design. GPT-5.1 costs 12x less per token.
GPT-5.1 is cheaper on both: 12× input, 12× output.
Per million tokens. Prices and uptime via OpenRouter, checked 8 Sep 2026.
GPT-5.1 uses 349.6x more bold