Over time, OpenAI has introduced a variety of AI models in ChatGPT, ranging from the classic GPT series to the newer o-series reasoning models. While having model choices is useful, it can also be confusing for everyday users. In this guide, I’ll break down all the ChatGPT models to help you choose the one that best fits your needs. Let’s dive into the details.
ChatGPT o
The o3 model in ChatGPT is a powerful reasoning AI and currently OpenAI’s most advanced model. It’s the full version designed to excel in coding, math, science, and visual understanding. This makes it ideal for tackling STEM-related questions and handling complex visual tasks. You can rely on o3 for in-depth answers, as it’s capable of processing and reasoning through highly intricate problems.
Additionally, o3 is a multimodal model, meaning you can upload images, charts, and diagrams for analysis. Its visual perception is highly advanced—capable of identifying locations from photos with impressive accuracy. As an agentic model, o3 can also tap into multiple tools within ChatGPT, including the Python interpreter, web search, file and image analysis, and image generation, allowing it to deliver comprehensive and well-informed responses.
Access to the o3 model is available through ChatGPT Plus and other paid plans. You can select it from the model drop-down menu in ChatGPT.
ChatGPT 4o
ChatGPT-4o, also known as GPT-4o, is OpenAI’s default model suited for a wide range of tasks. While it may not outperform specialized models in every area, it shines in general use. GPT-4o is particularly well-optimized for natural conversations, making it the best choice for chatting, writing, summarizing, and translating. As a traditional large language model, it often delivers better results than the o-series reasoning models when it comes to creative and language-centric tasks.
However, when it comes to STEM-related fields like coding, math, and science, GPT-4o falls short compared to models like o3. That said, GPT-4o is fully multimodal, which makes it a versatile choice for many tasks in ChatGPT. Features like native image generation and the Advanced Voice Mode are both powered by GPT-4o, highlighting its broad capabilities across different input types.
In fact, the popular Ghibli-style images you may have seen online are generated using the GPT-4o model. It also powers the Live Video feature in ChatGPT, which lets users share their camera or screen for real-time interaction. Beyond that, GPT-4o can analyze uploaded files and images, browse the web, perform advanced data analysis with Python, and support custom GPTs. Additionally, the Operator AI agent relies on GPT-4o’s vision capabilities.
To sum up, GPT-4o is ChatGPT’s flagship model for a variety of tasks and is accessible to both free and paid users. However, once free users hit the GPT-4o usage cap, their queries are switched over to the smaller GPT-4o mini model.
ChatGPT 4.5
GPT-4.5 is OpenAI’s largest non-reasoning language model, currently in research preview and available exclusively to paid subscribers. It stands out for its exceptional creative writing abilities outperforming other models when it comes to interpreting complex prompts, identifying patterns, and delivering imaginative responses without relying on deep reasoning.
According to OpenAI, GPT-4.5 has a higher Emotional Quotient (EQ), making conversations feel more natural and engaging. It’s also noted for its sense of humor, setting it apart from other models. GPT-4.5 is ideal for enhancing writing and programming tasks. While it’s no longer available via the API due to its large size, paid ChatGPT users can still access it from the “More models” menu.
ChatGPT o4-mini
o4-mini on ChatGPT is the next-generation reasoning AI model, succeeding the o3-series. It’s a more compact model, optimized for faster and more cost-efficient reasoning tasks. Like other reasoning models, o4-mini excels in math, coding, and visual tasks. Despite its smaller size, o4-mini actually outperforms the larger o3 model in coding and math.
In visual tasks as well, o4-mini offers competitive performance. While o3 benefits from being trained on a larger base model with a broader knowledge base, the compact o4-mini still holds its own. The o4-mini-high variant, which utilizes more compute power and processing time, performs even better in coding and visual reasoning.
Because of its small size and strong performance, OpenAI has made the o4-mini model available to free ChatGPT users by replacing the o3-mini model. Free users can access o4-mini by clicking the “Extended thinking” button. This model is ideal for STEM-related queries, coding tasks, and more challenging problems.
ChatGPT 4.1
OpenAI recently launched the GPT-4.1 model for developers via the API and later made it available on ChatGPT as well. This model is tailored for coders seeking improved instruction following and a larger context window. Unlike reasoning models, GPT-4.1 is optimized for coding tasks, and OpenAI recommends using it instead of GPT-4o for faster and more cost-effective performance.
GPT-4.1 supports a context window of up to 1 million tokens, excelling in long-context tasks. It also features an updated knowledge cutoff of June 2024. Additionally, the smaller GPT-4.1 mini and nano models offer solid coding performance at a significantly lower cost.
For faster, non-reasoning AI suited for coding tasks, choose the GPT-4.1 model in ChatGPT instead of GPT-4o. Keep in mind, this option is only available to paid ChatGPT users.
ChatGPT o1 pro
Since the release of o3 and o4-mini, many have forgotten about the o1 pro mode, but it’s still a powerful reasoning model based on the original o1. Instead of being a standalone reasoning model, it acts as a high-compute mode, leveraging more compute and processing time to solve tougher problems in math, science, and coding.
The o1 pro mode can spend several minutes analyzing complex problems to find a solution. Due to its high compute demands, it is only available to ChatGPT Pro subscribers, who pay $200 per month. OpenAI recently announced that a high-compute o3 pro mode is coming soon to replace the o1 pro mode for Pro users.
Codex-1
For programmers, OpenAI has introduced Codex, a new cloud-based software engineering AI agent. It’s powered by the ‘codex-1’ AI model, which is built on the o3 reasoning model and optimized specifically for coding tasks. OpenAI trained codex-1 using reinforcement learning (RL) on “real-world coding tasks across various environments to produce code that closely matches human style and pull request preferences.“
It can generate code, add new features, run and validate tests, create pull requests, and much more. OpenAI describes codex-1 as their best coding AI model. Although it’s not directly available within ChatGPT, you can access it through the ChatGPT sidebar. Note that you’ll need a ChatGPT Pro or higher-tier subscription to use this AI agent and model, but ChatGPT Plus users will gain access soon.
These are all the AI models available on ChatGPT, which you can choose based on your needs. For everyday queries, I recommend using GPT-4o, while the o3 reasoning model is best for STEM and coding challenges. If you have a free ChatGPT account, you can use the “Extended thinking” button to access the powerful o4-mini reasoning model.
Finally, OpenAI has phased out the DALL·E image generation model from ChatGPT. However, you can still use it as a custom GPT through this link. Additionally, OpenAI’s Sora AI model allows you to generate AI videos, though it isn’t integrated into ChatGPT. Lastly, the Deep Research AI agent is powered by a specialized version of the o3 reasoning model.
