GPT-4.5 is now available for ChatGPT Plus subscribers! OpenAI – AI model introduction process and availability – Image/Screenshot: Xpert.Digital
Strategic market launch: GPT-4.5 and user access
Following Pro and Team subscribers, now also exclusively for Plus (March 5, 2025): OpenAI's new approach with GPT-4.5
GPT-4.5 was released by OpenAI as a “Research Preview” on February 27, 2025, marking a significant advancement in the development of large language models. The new model was initially made available exclusively to ChatGPT Pro subscribers, with the rollout to Plus users beginning in early March 2025. This phased release reflects OpenAI’s strategic approach of making its latest technologies available to a limited user group before a wider rollout.
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The implementation process and availability
OpenAI launched GPT-4.5 as a “Research Preview” on February 27, 2025, initially granting access exclusively to users of the premium service ChatGPT Pro, which costs $200 per month. This selective access allowed the company to test the model under real-world conditions and gather feedback from paying users before making it available to a wider audience.
As announced by OpenAI, the phased rollout for Plus and Team subscribers began the following week. Sam Altman, CEO of OpenAI, confirmed on X on March 5, 2025, that the rollout of GPT-4.5 for Plus subscribers had officially begun and the process was expected to be completed within a few days. This staggered rollout was a deliberate choice to avoid system overload due to sudden surges in demand and to allow users extended real-time interaction with the new technology.
Altman explained in his posts on X (formerly Twitter) that OpenAI would have liked to make GPT-4.5 available to all users immediately, but this wasn't possible due to the need to start with a very low usage threshold. The full rollout plan stipulated that after Plus and Team users, Enterprise and Education users would also gain access in the second week.
Properties and capabilities of GPT-4.5
GPT-4.5 is described by OpenAI as their largest and best chat application model to date. It represents a significant advancement in scaling pre-training and post-training, with a focus on improving unsupervised learning. This distinguishes it from OpenAI's o1 and o3 models, which focus on reasoning skills.
Early tests show that interactions with GPT-4.5 feel more natural, which is attributed to its broader knowledge base, improved ability to capture user intent, and greater "emotional intelligence." These qualities make it particularly useful for tasks such as improving texts, programming, and solving practical problems.
A notable feature of GPT-4.5 is its enhanced ability to conduct conversations that, according to Sam Altman, feel “like talking to a thoughtful person.” The model offers a deeper level of sentiment analysis, with the ability to understand when to offer advice or simply listen when faced with emotionally charged requests.
GPT-4.5 also supports file and image uploads, enables the analysis of additional data, and boasts impressive multilingual capabilities in 14 languages, including Arabic, Bengali, Chinese, French, German, Hindi, Italian, Japanese, Korean, Spanish, and Swahili.
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Training methods and technical features
OpenAI employed a number of advanced techniques for the development and training of GPT-4.5. Building upon the foundation of GPT-40, it includes enhanced pre-training and other novel approaches to improve performance and reduce the risk of hallucinations.
Training techniques included supervised fine-tuning, where GPT-4.5 was adapted to human expectations and trained to effectively follow instructions. During this phase, OpenAI implemented advanced data filtering to minimize exposure to potentially harmful content. Additionally, Reinforcement Learning from Human Feedback (RLHF) was employed, with human evaluators ranking model outputs based on quality, helpfulness, and safety. Finally, GPT-4.5 was trained with Instruction Hierarchy Training to follow an instruction hierarchy that prioritizes system messages over conflicting user instructions to prevent prompt injections.
OpenAI did not disclose the exact size or number of parameters for GPT-4.5 at launch, but claimed that it was the largest model the company had ever built at the time of release. This emphasis on model size contrasts with other recent AI innovations that have sought to achieve frontier model performance with as few resources as possible.
Differences from previous models
GPT-4.5 builds on the foundations laid with GPT-4 and GPT-4o, introducing significant improvements in terms of accuracy, emotional intelligence, conversational naturalness, and user intent alignment.
A key difference between GPT-4o and GPT-4.5 lies in their focus: While GPT-4o was geared towards multimodal integration and could process text, images, and audio, GPT-4.5 focuses on scaled unsupervised learning and primarily processes text and images. Both models, however, support a context length of 128,000 tokens.
Another crucial difference lies in the pricing: While GPT-40 was relatively affordable at $2.50 per million input tokens and $10 per million output tokens, GPT-4.5 is significantly more expensive at $75 per million input tokens and $150 per million output tokens. This price difference reflects the increased complexity and computational effort required by GPT-4.5.
GPT-4.5 focuses on advancing unsupervised learning rather than chain-of-thought reasoning. Unlike reasoning-focused models such as o3 and DeepSeek R1, which use chain-of-thought processing to methodically think through complex problems, GPT-4.5 responds based on its training data and pattern recognition capabilities. This makes GPT-4.5 a more general-purpose model than specialized reasoning models, which excel in complex mathematics, science, and logic problems.
Costs and terms of use
GPT-4.5 is available to different user groups, but with varying access costs and conditions. ChatGPT Pro subscribers, who pay $200 per month, had access to GPT-4.5 from the start. ChatGPT Plus users received limited access starting in early March 2025.
For developers and organizations looking to integrate GPT-4.5 into their applications, access is possible via OpenAI's API, but at a significant cost: $75 per million input tokens and $150 per million output tokens. Alternatively, access is also available in a preview version via Microsoft's Azure OpenAI service.
OpenAI has pointed out that GPT-4.5 is a very large and computationally intensive model, making it more expensive than GPT-40, and is not positioning it as a replacement for that older model. Because of these costs, the company is evaluating whether to offer GPT-4.5 in its API in the long term, while balancing support for current features with the development of future models.
Future prospects and industry context
The release of GPT-4.5 occurred in a dynamic environment where several leading AI companies launched new models. OpenAI's GPT-4.5 debuted in the same week as Anthropic's Claude 3.7, released on February 24, 2025, shortly after xAI's Grok 3, which launched on February 18, 2025.
While GPT-4.5 represents a significant advancement, speculation continues regarding OpenAI's work on GPT-5, which has not yet been confirmed in the company's public roadmap. Within the AI community, there is growing debate about whether the approach of developing ever-larger models is reaching its limits—a view also shared by OpenAI's former chief scientist, Ilya Sutskever. The company's statements about GPT-4.5 appear to be a counter-argument to these skeptics.
OpenAI believes that reasoning will be a core capability of future models and that the two scaling approaches—pre-training and reasoning—will complement each other. With increasing intelligence and knowledge enrichment through pre-training, models like GPT-4.5 will serve as an even stronger foundation for reasoning and tool-using agents.
The introduction of GPT-4.5 underscores OpenAI's continued focus on scaling its models despite the financial and technical challenges associated with this approach. The coming months will reveal how this new model is received by the wider user community and what unexpected use cases might emerge.
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