What is ChatGPT 4?
ChatGPT 4 (GPT-4) was OpenAI's flagship model in 2023, offering enhanced language understanding and improved accuracy. It was retired from ChatGPT on April 30, 2025, and OpenAI's latest model is now GPT-6 Astra.
ChatGPT 4 represented a major advancement in AI conversational models. It featured enhanced language understanding, faster response times, and improved accuracy over its predecessor. Designed for professionals and power users, ChatGPT 4 offered a more robust interaction experience.
Models Available in ChatGPT 4
ChatGPT 4 came in several variants, including the core premium ChatGPT 4 Standard model. None of them remain in ChatGPT today.
The ChatGPT 4 series came in several variants, each tailored to different user needs. Here’s an overview of the main models:
- ChatGPT 4 Standard: The core premium model offering improved accuracy and context handling.
- ChatGPT 4 Turbo: A variant optimized for faster responses and cost efficiency.
- ChatGPT 4o: An optimized model variant with enhanced performance for complex queries, retired from ChatGPT on February 13, 2026.
Comparing ChatGPT Free and ChatGPT 4
ChatGPT 4 offered advanced reasoning and creativity over ChatGPT Free, which used the GPT-3.5 model at the time.
Below is how ChatGPT Free (then powered by GPT-3.5) compared with the standard ChatGPT 4 model:
| Feature | ChatGPT Free (3.5) | ChatGPT 4 (Standard) |
|---|
| Language Understanding | Good for casual queries | Enhanced contextual comprehension |
| Response Speed | Moderate | Faster, optimized processing |
| Access to Features | Basic | Premium features and priority access |
| Usage Cost | Free | Subscription-based |
Comparison Among ChatGPT 4 Models
ChatGPT 4 models differed in their capabilities and access, and none of them remain in ChatGPT today.
The ChatGPT 4 series included several variants. The table below compares the key aspects of each model:
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| Model | Key Features | Performance | Use Case |
|---|
| ChatGPT 4 Standard | Enhanced language understanding, detailed responses | High | General professional use |
| ChatGPT 4 Turbo | Faster response times, cost-effective | Very High | Time-sensitive tasks |
| ChatGPT 4o | Optimized for complex queries, improved accuracy | High | Advanced research and analysis |
FAQ Section
GPT-4 is retired, so today the choice is between plans: Free runs GPT-5.6 Luna and paid plans run GPT-5.6 Sol.
- Is ChatGPT 4 worth the upgrade?
GPT-4 is no longer available in ChatGPT. If you need more capable responses, Plus ($20/month) adds GPT-5.6 Sol with Medium and High thinking levels. - Can I still use ChatGPT for free?
Yes, ChatGPT Free remains available for casual use, running on GPT-5.6 Luna by default. - What are the differences among ChatGPT 4 models?
The ChatGPT 4 models differed in performance, speed, and cost, from the standard model to Turbo and 4o. All of them have since been retired from ChatGPT.
Conclusion
In summary, ChatGPT Free (originally powered by GPT-3.5) offered a solid foundation for casual use, while the advanced features of ChatGPT 4 and its variants, including the optimized ChatGPT 4o, brought significant benefits for professional and high-demand tasks. All of those models are now retired from ChatGPT.
Whether you choose the free plan or upgrade to a paid plan, each option is designed to empower your AI interactions. Evaluate your needs and select the model that best fits your workflow.
External Resources
OpenAI's official website and the ChatGPT platform are key external resources for information.
Last updated: September 15, 2026
Key Terms
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- Free Plan
- 2 folders, 2 pinned chats, 2 saved prompts, 5 search results, media gallery, RTL support, and device sync - free forever.
- Premium
- $9.99/month or $99 one-time lifetime - unlimited folders, unlimited search results, bulk exportPremium, and unlimited prompt chains.
Bottom Line
GPT-4 and GPT-4o are no longer in ChatGPT: GPT-4 was retired on April 30, 2025 and GPT-4o on February 13, 2026. Today ChatGPT Free runs GPT-5.6 Luna at no cost, while ChatGPT Plus ($20/month) runs GPT-5.6 Sol. This comparison covers reasoning accuracy, speed, available features, usage limits, and real-world performance.
References
Sources, tool names, and authoritative documentation referenced in this article:
Retrieved May 2026.
Adi Leviim