OpenAI · reasoning LLM
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.
Capabilities
- ▸Extended step-by-step reasoning before answering
- ▸Competition-level mathematics and physics problems
- ▸Complex code generation and debugging
- ▸Scientific and legal analysis over long documents
- ▸Image understanding as part of a reasoning chain
Use cases
research · maths and science · hard debugging · structured analysis
Lineage
View the full OpenAI o1 lineage →OpenAI o1 head-to-head comparisons
- OpenAI o3 vs o1o3 vs o1: OpenAI's second-generation reasoning model against the first.
- DeepSeek R1 vs OpenAI o1Two reasoning models with the same basic idea and very different licences: DeepSeek R1 ships open weights you can self-host, while OpenAI o1 is API-only but stronger on the hardest multi-step problems.
- OpenAI o1 vs GPT-5o1 was the first dedicated reasoning model; GPT-5 folds that reasoning into a general-purpose model that is faster, cheaper and stronger almost everywhere.
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Sources & verification
Information is compiled from official announcements, documentation and reputable industry coverage.
Last verified Sep 19, 2026