Model comparison
GPT-5.1 Pro vs GPT-5 Pro
- Input
- No published API price
- Output
- No published API price
- Context
- GPT-5.1 Pro ran inside ChatGPT, where OpenAI did not publish a token context limit for the Pro tier. The GPT-5.1 API model it is based on uses a 400,000-token context window.
- Released
- 2025-11-19
- Input
- $15.00
- Output
- $120.00
- Context
- 400K
- Released
- 2025-08-07
GPT-5 Pro has the larger context window (400K vs 0K).
Specs and pricing side by side
| Spec | GPT-5.1 Pro | GPT-5 Pro |
|---|---|---|
| Maker | OpenAI | OpenAIsame |
| Released | 2025-11-19 | 2025-08-07 |
| Context window | GPT-5.1 Pro ran inside ChatGPT, where OpenAI did not publish a token context limit for the Pro tier. The GPT-5.1 API model it is based on uses a 400,000-token context window. | 400K |
| Max output | Not separately published for the ChatGPT Pro… | 128K |
| Input price | No published API price | $15.00 |
| Output price | No published API price | $120.00 |
| Parameters | Not disclosed by OpenAI. | Undisclosed |
| License | Proprietary (OpenAI). Available through ChatGPT subscriptions under OpenAI's terms of use; not open-weight. | Proprietary |
| Weights | API only | API onlysame |
| Modalities | Text input, Image input, Text output | Text, Vision |
| Knowledge cutoff | Not separately published for GPT-5.1 Pro. The… | not published |
Benchmarks both models report
These two models have no benchmark in common in our registry, so there is no like-for-like score to compare. See each model’s own results: GPT-5.1 Pro, GPT-5 Pro.
Which one should you pick?
Pick GPT-5.1 Pro if…
- You need Text input / Image input / Text output input, which GPT-5 Pro lacks.
- Your use case is: tackling difficult technical or scientific questions where answer quality matters more than latency.
Pick GPT-5 Pro if…
- You need the longer context (400K vs 0K).
- You need Text / Vision input, which GPT-5.1 Pro lacks.
- Your use case is: research-grade science, math, and finance problems where answer quality outweighs cost.
FAQ
Which is better, GPT-5.1 Pro or GPT-5 Pro?
GPT-5 Pro has the larger context window (400K vs 0K). The better pick depends on whether you value benchmark scores, price per token, context length or openness for your workload.
What are the context windows of GPT-5.1 Pro and GPT-5 Pro?
GPT-5.1 Pro offers GPT-5.1 Pro ran inside ChatGPT, where OpenAI did not publish a token context limit for the Pro tier. The GPT-5.1 API model it is based on uses a 400,000-token context window. with up to Not separately published for the ChatGPT Pro tier. The GPT-5.1 API model supports up to 128,000 output tokens. output; GPT-5 Pro offers 400K with up to 128K output.
Is GPT-5.1 Pro newer than GPT-5 Pro?
GPT-5.1 Pro was released 2025-11-19; GPT-5 Pro was released 2025-08-07.