OpenAI Introduces New o3 and o4-mini Reasoning Models

OpenAI just dropped two new AI models, o3 and o4-mini, the latest in its o-series built to think harder before answering. These are the smartest models the company has released so far, able to tap into ChatGPT's full toolkit to handle everything from web searches to image analysis.

OpenAI o3 is our most powerful reasoning model that pushes the frontier across coding, math, science, visual perception, and more. It sets a new SOTA on benchmarks including Codeforces, SWE-bench (without building a custom model-specific scaffold), and MMMU. It's ideal for complex queries requiring multi-faceted analysis and whose answers may not be immediately obvious. It performs especially strongly at visual tasks like analyzing images, charts, and graphics. In evaluations by external experts, o3 makes 20 percent fewer major errors than OpenAI o1 on difficult, real-world tasks—especially excelling in areas like programming, business/consulting, and creative ideation. Early testers highlighted its analytical rigor as a thought partner and emphasized its ability to generate and critically evaluate novel hypotheses—particularly within biology, math, and engineering contexts.

OpenAI o4-mini is a smaller model optimized for fast, cost-efficient reasoning—it achieves remarkable performance for its size and cost, particularly in math, coding, and visual tasks. It is the best-performing benchmarked model on AIME 2024 and 2025. In expert evaluations, it also outperforms its predecessor, o3‑mini, on non-STEM tasks as well as domains like data science. Thanks to its efficiency, o4-mini supports significantly higher usage limits than o3, making it a strong high-volume, high-throughput option for questions that benefit from reasoning.


OpenAI says that external expert evaluators rated both models as demonstrating improved instruction following and more useful, verifiable responses than their predecessors, thanks to improved intelligence and the inclusion of web sources. Compared to previous iterations of its reasoning models, these two models should feel more natural and conversational, especially as they reference memory and past conversations to make responses more personalized and relevant.

Availability
ChatGPT Plus, Pro, and Team users will see o3, o4-mini, and o4-mini-high in the model selector starting today, replacing o1, o3‑mini, and o3‑mini‑high. ChatGPT Enterprise and Edu users will gain access in one week. Free users can try o4-mini by selecting 'Think' in the composer before submitting their query. Rate limits across all plans remain unchanged from the prior set of models.

OpenAI expects to release OpenAI o3‑pro in a few weeks with full tool support. For now, Pro users can still access o1‑pro.

Both o3 and o4-mini are also available to developers today via the Chat Completions API and Responses API (some developers will need to verify their organizations⁠(opens in a new window) to access these models). The Responses API supports reasoning summaries, the ability to preserve reasoning tokens around function calls for better performance, and will soon support built-in tools like web search, file search, and code interpreter within the model's reasoning.


More details and benchmarks in the full announcement linked below...

Read More