Comparison · Updated Oct 5, 2026
OpenAI o3 vs o1
o3 vs o1: OpenAI's second-generation reasoning model against the first.
At a glance
| Spec | OpenAI o3 | OpenAI o1 |
|---|---|---|
| Released | Apr 16, 2025 | Dec 5, 2024 |
| Context window | 200K tokens | 200K tokens |
| Licence | Closed / API | Closed / API |
| Inputs | text, image | text, image |
| Public API | Yes | Yes |
Model A
OpenAI o3
OpenAI o3 is the successor to o1 in OpenAI's reasoning line. Released in April 2025, it can call tools such as web search and Python while it reasons, and it reasons over images as well as text.
Apr 16, 2025
Model B
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.
Dec 5, 2024
Differences
| Attribute | OpenAI o3 | OpenAI o1 |
|---|---|---|
| Released | Apr 2025 | Dec 2024 |
| Tool use while reasoning | Yes | No |
| Context window | 200K | 200K |
Verdict
o3 replaces o1 for almost all reasoning work: it is more accurate and can use tools while it reasons.
Analysis
The short version o1 (December 2024) introduced private chain-of-thought reasoning. o3 (April 2025) keeps that approach and adds tool use (web search, Python, image analysis) inside the reasoning loop.
Accuracy o3 scores higher on maths, science and coding, and makes fewer major errors on hard real-world tasks.
Tools and images o3 can decide to search, run code or zoom into an image mid-thought. o1 cannot.
Frequently asked
- Is o3 better than o1?
- Yes. o3 is more accurate and can use tools during reasoning.