OpenAI o1 vs GPT-5
o1 was the first dedicated reasoning model; GPT-5 folds that reasoning into a general-purpose model that is faster, cheaper and stronger almost everywhere.
| Spec | OpenAI o1 | GPT-5 |
|---|---|---|
| Released | Dec 5, 2024 | Aug 7, 2025 |
| Context window | 200K tokens | 400K tokens |
| Licence | Closed / API | Closed / API |
| Inputs | text, image | text, image |
| Public API | Yes | Yes |
OpenAI o1
OpenAI o1 is a reasoning model that thinks through a problem internally before replying, trading latency and cost for much higher accuracy on maths, science and difficult programming tasks. It reached general availability in December 2024 and set the template for later reasoning models.
GPT-5
OpenAI's next-generation flagship model succeeding GPT-4o.
Differences
| Attribute | OpenAI o1 | GPT-5 |
|---|---|---|
| Released | December 2024 | August 2025 |
| Context window | 200K tokens | 400K tokens |
| Reasoning control | Always on | Adjustable |
| Relative cost | High | Moderate |
| Best for | Historical reference | New production work |
Verdict
Analysis
What changed
o1 (December 2024) separated reasoning into its own slow, expensive model. GPT-5 (August 2025) integrates adjustable reasoning into one model, so you no longer choose between speed and thinking.
Practical impact
GPT-5 has a larger context window, better tool use and lower cost per useful answer. o1 remains historically important and is still referenced in benchmark literature.
Frequently asked
- Should I still build on o1?
- No. GPT-5 supersedes it on quality, latency and price for essentially all new work.