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Since its launch, ChatGPT has evolved significantly, offering various models each designed to meet different user needs. This guide explains each ChatGPT model in clear, easy-to-understand language, helping you choose the best one for your task.

What are ChatGPT models?

ChatGPT is a chatbot powered by artificial intelligence from OpenAI. Behind it are different versions, or “models,” each with strengths and specific uses. These models affect how well ChatGPT understands your questions and provides useful answers.

Let's explore these models step-by-step.

1. GPT-3.5: The Original Model

GPT-3.5 started it all. Launched in November 2022, it quickly became popular due to its conversational abilities.

• Memory: Can remember around 3,000-4,000 words.
• Strengths: Fast, free to use, good for simple questions and basic tasks.
• Weaknesses: Struggles with complex tasks and occasionally makes mistakes (“hallucinations”).

GPT-3.5 Turbo, an upgraded version, improved performance and response speed, becoming popular for basic chat tasks and quick responses.

2. GPT-4: A Significant Upgrade

In March 2023, OpenAI introduced GPT-4, a smarter model with major improvements.

• Memory: Can handle around 6-7 pages of text at once (8,000 tokens). A special version can manage around 50 pages (32,000 tokens).
• Strengths: Excellent at complex reasoning, detailed analysis, coding, and creative writing. It can even understand images.
• Weaknesses: Slower and more expensive to use compared to GPT-3.5.

GPT-4 is perfect for detailed tasks, like analyzing documents or assisting with complex writing.

3. GPT-4 Turbo and GPT-4 Mini: Faster and More Efficient

To solve GPT-4's issues of speed and cost, OpenAI released GPT-4 Turbo and GPT-4 Mini in late 2023.

GPT-4 Turbo

• Memory: Extremely large, capable of handling about 100 pages at once (128,000 tokens).
• Strengths: Faster, cheaper, and updated with more recent knowledge (up to April 2023).
• Use Case: Best for analyzing large documents or having very long conversations.

GPT-4 Mini (also known as GPT-4o Mini)

• Memory: Moderate, about 8,000 tokens (similar to GPT-4).
• Strengths: Faster, cheaper, and more capable than GPT-3.5.
• Use Case: Good for everyday questions, quick tasks, and basic assistance.

GPT-4 Mini became the default for free users, improving the quality of responses significantly.

4. GPT-4o: Powerful and Versatile

GPT-4o is an advanced model introduced for ChatGPT Plus subscribers.

• Strengths: Handles writing, complex analysis, coding tasks, and image understanding effectively.
• Speed: Slightly slower than GPT-4 Mini, but more capable overall.
• Use Case: Ideal for deeper tasks, research, detailed documents, and refining drafts.

Many users start with GPT-4 Mini for initial work and then refine results using GPT-4o.

5. GPT-4.5: Advanced and Creative

GPT-4.5, released in early 2025, is OpenAI’s experimental model for advanced creative tasks.

• Strengths: Better at understanding emotional context, creative writing, storytelling, and empathetic conversations.
• Weaknesses: Experimental—results can vary, making it less reliable for everyday tasks.
• Availability: Initially exclusive to Pro subscribers, later available to more users gradually.

Use GPT-4.5 for sensitive or highly creative tasks, such as writing speeches, stories, or emotional content.

6. The OpenAI “o” Series: Specialized for Reasoning

OpenAI developed the “o” series to specialize in tasks requiring logical reasoning and problem-solving skills.

o3-mini

• Strengths: Highly effective at solving math, science, and programming problems step-by-step. It also verifies its answers using web search.
• Availability: Introduced as a beta option for all users.

Choose o3-mini when facing complicated logical tasks, coding challenges, or difficult math questions.

7. GPT-4.1 Series: For Developers and Big Tasks

The GPT-4.1 series is targeted mainly at developers and specialized applications. It includes three models: GPT-4.1, Mini, and Nano.

• Memory: Exceptional, supporting up to 1 million tokens—essentially entire books or large databases at once.
• Strengths: Ideal for coding, software engineering, and tasks that require handling huge amounts of information.
• Availability: Currently only accessible through developer APIs.

These models work best behind-the-scenes, powering apps, customer service bots, or programming tools.

What About Older Models Like GPT-3.5?

While GPT-3.5 and Turbo models were reliable, they're gradually being replaced by newer models offering better memory, speed, and accuracy. GPT-4o Mini now provides better performance at no cost, becoming the new standard for most users.

ChatGPT Subscription Plans Explained

Understanding the difference between ChatGPT Plus and Pro is important:

ChatGPT Plus ($20/month)

• Who it's for: Individuals and small teams needing quicker responses and access to advanced models like GPT-4o.

ChatGPT Pro ($200/month)

• Who it's for: Professional users, researchers, or developers needing the highest speeds, advanced features, and early access to experimental models.

There's also ChatGPT Enterprise, designed for businesses needing unlimited use, enhanced security, and custom features.

Looking Forward: GPT-5 and the Future

OpenAI plans to release GPT-5, a future model combining the best features from existing ones—both knowledge-based and reasoning-based.

• What to expect: A smarter, more flexible AI that adapts to different tasks seamlessly. Free users will get a basic version, while subscribers will enjoy advanced features.

GPT-5 aims to simplify AI usage, removing the need to choose between multiple models and making ChatGPT smarter and easier to use.

Which is the best ChatGPT Model?

It depends on your task. GPT-4o is usually the best ChatGPT model to use by default because it handles most tasks very well. However, simpler or specialized tasks might benefit from other models tailored specifically to those needs.

• Simple, daily tasks: GPT-4o Mini
• Complex writing and analysis: GPT-4o
• Creative writing and emotional tasks: GPT-4.5
• Detailed reasoning and logic: o3-mini
• Programming and extensive documents: GPT-4 Turbo or GPT-4.1 (for developers)

Choosing the right model improves the speed, accuracy, and usefulness of your results, making your ChatGPT experience smoother and more productive.

About the Author

This article was written by Genaro Palma and it was originally published at JustAINews, under the name “All ChatGPT Models Explained: Which One Should You Use?”.