Over time, OpenAI has added several new AI models to ChatGPT, from traditional GPT-series LLMs to o-series reasoning models. While the ability to select a model based on your use case is fine, for general consumers, it adds to more confusion. So in this article, I have explained all ChatGPT models so you can pick the right one for your task. On that note, let’s learn about ChatGPT models in detail.
ChatGPT o3
The o3 model on ChatGPT is a reasoning AI model, and it’s OpenAI’s most capable model right now. It’s the full o3 model that excels at coding, math, science, and visual perception. So the o3 model should be used for STEM (Science, Technology, Engineering, and Math)-related questions and visual tasks. You can throw the most complex questions at o3, and it will think for several minutes to generate a proper response.
In addition, it’s a multimodal model, so you can upload images, charts, and diagrams as well. In fact, o3’s visual perception is so powerful that it can accurately identify location by analyzing photos. On top of that, o3 is an agentic model, which means it can access multiple tools inside ChatGPT such as the Python interpreter, web search, file analysis, image analysis/generation, etc., to generate a fleshed-out response.
The o3 model is only accessible on ChatGPT Plus and other paid plans and you can use it from the ChatGPT drop-down menu.
ChatGPT 4o
ChatGPT 4o or GPT-4o is OpenAI’s default AI model for all kinds of tasks. It’s not the best model in every area, but it’s no slouch either. GPT-4o is the best chat model, designed by OpenAI for regular conversations. Since it’s a traditional LLM, for creative tasks like writing, summarizing, chatting, and translation, GPT-4o performs better than o-series reasoning models.
However, in STEM-related areas including coding, math, and science, GPT-4o ranks below the likes of o3. What is interesting about GPT-4o is that it’s fully multimodal, and OpenAI leverages it for several tasks on ChatGPT. The native image generation feature in ChatGPT is powered by GPT-4o. Next, the Advanced Voice Mode uses the GPT-4o model under the hood.
In fact, the viral Ghibli images are produced by the GPT-4o model. Next, Live Video in ChatGPT that allows users to share their camera or screen for real-time interaction, is also powered by GPT-4o. Not to mention, GPT-4o can analyze uploaded files and images, browse the web, use advanced data analysis through Python, and power custom GPTs too. Not to forget, the Operator AI agent uses GPT-4o’s vision capability.
To sum up, GPT-4o is a flagship model on ChatGPT for a wide range of tasks, and it’s available to both paid and free users. Note that once free users exhaust the GPT-4o usage limit, queries are routed to a smaller GPT-4o mini model.
ChatGPT 4.5
ChatGPT 4.5 or GPT-4.5 is OpenAI’s largest non-reasoning LLM. It’s currently in research preview and only available to paid subscribers. The GPT-4.5 model excels at creative writing, much better than any other model out there. It can recognize patterns from complex prompts, draw connections, and produce creative insights without using reasoning.
OpenAI says GPT-4.5 has a greater “EQ” (Emotional Quotient) that makes the interaction feel much more natural. It’s also more humorous than other models. You should use GPT-4.5 to improve writing and programming. Note that since the GPT-4.5 model is pretty large, OpenAI has phased it out from the API, but paid users can still access it under “More models” in ChatGPT.
ChatGPT o4-mini
o4-mini on ChatGPT is the next-generation reasoning AI model, successor to the o3-series. It’s a smaller model, designed for faster and cost-efficient reasoning tasks. Just like any other reasoning model, o4-mini shows excellence in math, coding, and visual tasks. Despite being much smaller in size, o4-mini actually delivers better performance in coding and math, compared to the larger o3 model.
In visual tasks too, o4-mini delivers competitive performance. Since o3 is trained on a larger base model, it has an expanded knowledge base, but the compact o4-mini is no slouch either. The o4-mini-high model which uses more compute resources and thinking time, is even better at coding and visual reasoning.
Since it has a small size and great performance, OpenAI has brought the o4-mini model to free ChatGPT users as well, by replacing the o3-mini model. You can click on the “Extended thinking” button to use the o4-mini model on the free version of ChatGPT. You should use this model for STEM-related queries, coding questions, and harder problems.
ChatGPT 4.1
OpenAI recently introduced the GPT-4.1 model for developers in the API. However, later, the company brought the GPT-4.1 model to ChatGPT as well. This model is specifically designed for coders who want better instruction following and a larger context window. It’s not a reasoning model, and OpenAI recommends using the GPT-4.1 for coding tasks instead of GPT-4o for faster and cheaper performance.
GPT-4.1 supports up to 1 million tokens in the context window and does extremely well in long-context tasks. It also has a refreshed knowledge cutoff of June 2024. Other than that, the smaller GPT-4.1 mini and nano models deliver decent coding performance at a much cheaper price.
If you want to use a faster, non-reasoning AI model for coding tasks, pick the GPT-4.1 model in ChatGPT instead of GPT-4o. Bear in mind that it’s only available to paid ChatGPT users.
ChatGPT o1 pro
With the release of o3 and o4-mini, many have forgotten about the o1 pro mode, but it’s a powerful reasoning model that is based on the first o1 model. It’s more of a high-compute mode, rather than a standalone reasoning model. The o1 pro mode uses more compute and thinking time to solve harder problems related to math, science, and coding.
The o1 pro mode can think for several minutes to analyze complex problems and find a solution. Since it uses more compute resources, the o1 pro mode is only available to ChatGPT Pro subscribers, which costs $200 per month. OpenAI recently said that a high-compute o3 pro mode is coming soon, which will replace the o1 pro mode for Pro users.
Codex-1
For programmers, OpenAI has launched a new, cloud-based software engineering AI agent called Codex. It’s powered by a new ‘codex-1’ AI model which is based on the o3 reasoning model and optimized for coding tasks. OpenAI has trained the codex-1 model using reinforcement learning (RL) on “real-world coding tasks in a variety of environments to generate code that closely mirrors human style and PR preferences.”
It can generate code, add new features, run and validate tests, create PR, and so much more. OpenAI says codex-1 is the company’s best coding AI model. While it’s not directly available in ChatGPT, you can access it from the ChatGPT sidebar. Keep in mind that you will need ChatGPT Pro or a higher-tier subscription to access the AI agent and model. ChatGPT Plus users will get access pretty soon.
So these are all the AI models available on ChatGPT, and you can use them based on your requirements. I would recommend using the GPT-4o for everyday queries, and the o3 reasoning model for STEM and coding problems. And if you have a free ChatGPT account, you use the “Extended thinking” button to use the excellent o4-mini reasoning model.
Finally, OpenAI has phased out its image generation model, Dall -E from ChatGPT. However, you can use it as a custom GPT from this link. In addition, OpenAI’s Sora AI model lets you generate AI videos, but it’s not part of ChatGPT. Lastly, the Deep Research AI agent is powered by a special version of the o3 reasoning model.
