GPT 4.5: How to Access and Use It

A new model drops every few months, and suddenly, what seemed cutting-edge yesterday feels outdated.

This time, it’s GPT-4.5, OpenAI’s latest AI model.

For months, everyone was hyped about what was next—most assumed GPT-5 was around the corner. Turns out, OpenAI had a different plan. GPT-4.5 is the newest upgrade, and while it’s not GPT-5, it’s still a major step forward.

It’s bigger, smarter, and more compute-hungry than anything else OpenAI has made public. Plus, it’s designed to understand nuance better than ever, making it even sharper at following instructions and grasping complex requests.

So, what does this mean for you? Let’s break it down—what GPT-4.5 brings, how to access it, and where it fits in OpenAI’s AI roadmap.

What Is GPT-4.5?

GPT-4.5 is OpenAI’s most recent, largest and most powerful model in the GPT series, representing the next natural step in OpenAI’s ongoing AI evolution.

However, what makes GPT-4.5 interesting isn’t just its size or power—it’s that it stands in stark contrast to the recent trend in AI innovation.

Lately, the AI industry has been shifting toward reasoning-first models, with models like DeepSeek and other competitors from China emphasizing structured problem-solving over brute-force knowledge.

Newer models are also trying to replicate the performance of more established model lines with less compute and resources. Even OpenAI itself has leaned into reasoning-focused refinements with recent GPT iterations.

But GPT-4.5 doesn’t follow this trend. Instead, it sticks to OpenAI’s core philosophy: bigger is better.

More training data. More compute. More knowledge.

The idea behind this approach is simple: the more an AI model knows, the less it needs to make up. By vastly expanding its knowledge base and compute power, GPT-4.5 aims to reduce hallucinations, improve contextual understanding, and provide more reliable, nuanced responses.

While it may not be a "reasoning-first" model in the same way as some of its newer rivals, GPT-4.5 is still OpenAI’s most powerful AI yet. It continues the company’s maximalist approach, proving that sheer scale and information depth remain OpenAI’s strongest assets in the AI race.

How to Access GPT-4.5

If you want to try GPT-4.5, here are the available options:

1. ChatGPT Pro Users ($200 Plan)

GPT-4.5 is currently exclusive to ChatGPT Pro users, the $200 per month plan.
If you're on ChatGPT Pro, you already have access to OpenAI's most powerful AI model.

2. ChatGPT+ ($20), ChatGPT EDU, and ChatGPT Enterprise

GPT-4.5 will roll out to ChatGPT+ ($20/month), ChatGPT EDU, and ChatGPT Enterprise users in the coming weeks.
If you're subscribed to one of these plans, you don’t have access yet, but OpenAI has confirmed that GPT-4.5 is coming soon.

3. OpenAI API Access

OpenAI has released GPT-4.5 through its API, allowing developers to integrate it into their applications.
Pricing for API access is very high; around 30x the cost of previous models.

4. Microsoft Partners

Microsoft is expected to integrate GPT-4.5 into its AI-powered offerings soon.
Services like Copilot in Microsoft 365 and Azure OpenAI Service will likely offer GPT-4.5-powered capabilities, similar to past models.

5. Access GPT-4.5 via Chatbase

If you don’t have a ChatGPT Pro subscription but still want to try GPT-4.5, Chatbase provides an alternative. You can access GPT-4.5 on Chatbase right now!
Developers can access GPT-4.5 via Chatbase without having to build complex systems from scratch.If you’re looking to build an AI chatbot, AI agent, or a conversational AI tool for your website or application, you don’t need to construct an entire infrastructure from the ground up. Chatbase has already done the heavy lifting.
Train GPT-4.5 with your own data in minutes.
Have business data, company knowledge, or any domain-specific information you want GPT-4.5 to understand? Chatbase makes it ridiculously easy. Just log in, upload your data, and your GPT-4.5 instance is instantly trained. Then, by simply connecting the Chatbase API to your app, your AI will be fully equipped with your custom knowledge.

→ Get started: Try GPT-4.5 on Chatbase right now!

The level of nuance, the depth of understanding, the way it grasps context and delivers responses—is indeed worth a second look. It feels sharper, more intuitive, and just way more capable.

If you haven’t tried GPT-4.5 yet, you definitely should!

The difference between GPT-4 and GPT-4.5 is expected to be similar to the gap between GPT-3.5 and GPT-4. That means a significant step up in capability, but not a completely new paradigm.

According to OpenAI CEO Sam Altman, GPT-4.5 will likely be the last non-chain-of-thought model OpenAI releases.

This marks a turning point. OpenAI is shifting toward a different kind of AI architecture. That means GPT-4.5 could be the last model of its kind.

GPT-4.5 represents the end of an era, yet it also represents the beginning of something new.

GPT Timeline: From GPT-3.5 to GPT-4.5

While OpenAI has released models like GPT-1, GPT-2, and GPT-3, the real turning point for AI's mass-market adoption came with GPT-3.5. This was the moment when AI truly became mainstream, powering ChatGPT and revolutionizing how people interacted with AI models.

November 2022 – GPT-3.5

GPT-3.5 launched with ChatGPT, marking the start of mass-market AI adoption and setting the stage for conversational AI at scale.

March 2023 – GPT-4

OpenAI introduced GPT-4, its first truly multimodal model, capable of processing both text and images.
This release significantly improved reasoning, creativity, and problem-solving.

2023 – 2024: Iterative Updates (GPT-4 Turbo, GPT-4-0314, etc.)

OpenAI refined GPT-4 with models like GPT-4-0314 and GPT-4 Turbo, optimizing for speed, cost-efficiency, and longer context windows.
These iterations focused on delivering better performance at scale.

2024 – The Rise of Reasoning Models

Towards the end of 2024, OpenAI and other AI companies shifted towards reasoning-based models, where structured step-by-step thinking became the core competitive advantage.