OpenAI launches a pair of AI reasoning models, o3 and o4-mini

OpenAI announced on Thursday the launch of o3 and o4-mini, new AI reasoning models designed to pause and work through questions before responding.

The company calls o3 its most advanced reasoning model ever, outperforming the company’s previous models on tests measuring math, coding, reasoning, science, and visual understanding capabilities. Meanwhile, o4-mini offers what OpenAI says is a competitive trade-off between price, speed, and performance — three factors developers often consider when choosing an AI model to power their applications.

Unlike previous reasoning models, o3 and o4-mini can generate responses using tools in ChatGPT such as web browsing, Python code execution, image processing, and image generation. Starting today, the models, plus a variant of o4-mini called o4-mini-high that spends more time crafting answers to improve its reliability, are available for subscribers to OpenAI’s Pro, Plus, and Team plans.

The new models are part of OpenAI’s effort to beat out Google, Meta, xAI, Anthropic, and DeepSeek in the cutthroat global AI race. While OpenAI was first to release an AI reasoning model, o1, competitors quickly followed with versions of their own that match or exceed the performance of OpenAI’s lineup. In fact, reasoning models have begun to dominate the field as AI labs look to eke more performance out of their systems.

O3 nearly wasn’t released in ChatGPT. OpenAI CEO Sam Altman signaled in February that the company intended to devote more resources to a sophisticated alternative that incorporated o3’s technology. But competitive pressure seemingly spurred OpenAI to reverse course in the end.

OpenAI says that o3 achieves state-of-the-art performance on benchmarks including Codeforces, SWE-bench
(without building a custom model-specific scaffold), and MMMU.

OpenAI claims that o3 and o4-mini are its first models that can “think with images.” In practice, users can upload images to ChatGPT, such as whiteboard sketches or diagrams from PDFs, and the models will analyze the images during their “chain-of-thought” phase before answering. Thanks to this newfound ability, o3 and o4-mini can understand blurry and low-quality images and can perform tasks such as zooming or rotating images as they reason.

Beyond image processing capabilities, o3 and o4-mini can run and execute Python code directly in your browser via ChatGPT’s Canvas feature, and search the web when asked about current events.

In addition to ChatGPT, all three models — o3, o4-mini, and o4-mini-high — will be available via OpenAI’s developer-facing endpoints, the Chat Completions API and Responses API, allowing engineers to build applications with the company’s models at usage-based rates. In the coming weeks, OpenAI says it plans to release o3-pro, a version of o3 that uses more computing resources to produce its answers, exclusively for ChatGPT Pro subscribers.

OpenAI CEO Sam Altman has indicated o3 and o4-mini may be its last standalone AI reasoning models in ChatGPT before GPT-5, a model that the company has said will unify traditional models like GPT-4.1 with its reasoning models.