OpenAI Launches GPT-4.5 for ChatGPT—It’s Huge and Compute-Intensive

GPT-4.5 is here, and OpenAI’s newest generative AI model is bigger and more compute-intensive than ever—it’s supposedly also better at understanding what ChatGPT users mean with their prompts. Users who want to be part of the first wave to try GPT-4.5, labeled as a research preview, will be required to pay for OpenAI’s $200-a-month ChatGPT Pro subscription.

Prior to this launch, 2025 has already been filled with new AI model releases. Anthropic recently put out a hybrid reasoning model for its Claude chatbot. Before that, Chinese researchers at DeepSeek rocked Silicon Valley with their release of a powerful model trained on a tiny budget, prompting OpenAI to drop a “mini” version of its reasoning model a month ago.

Alongside these new releases, OpenAI promised to invest billions into building the AI infrastructure required to fuel more massive models. And GPT-4.5 is a reiteration of this current strategy from the startup: Bigger is better.

ChatGPT 4.5 is in stark contrast to other recent AI innovations, like DeepSeek’s R1, that attempted to match the performance of a frontier model with as few resources as possible. OpenAI still sees a strong path forward through scaling its models. According to researchers who worked on GPT-4.5, this kind of maximalist mindset to model development has captured more of the nuances of human emotions and interactions.

They see the model’s size as also potentially helping this iteration hallucinate with less frequency than past releases. “If you know more things, you don’t need to make things up,” says Mia Glaese, who leads OpenAI’s alignment team and human data team. Exactly how big or compute-intensive GPT-4.5 is remains unclear—OpenAI declined to share specific numbers.

So, what’s it like to use the new model? Pro users are getting a first look, with rollouts for Plus and Team users scheduled for next week and Enterprise and Edu the week afterwards. GPT-4.5 supports the web search and canvas feature as well as uploads of files and images, though it’s not yet compatible with the AI Voice Mode.

In the announcement post for GPT-4.5, OpenAI included academic benchmark results that show the model getting vastly outpaced by the o3-mini model when it comes to math, and slightly upstaged on science as well, though GPT-4.5 did score a little higher on language benchmarks. The researchers say these measurements don’t capture the full story. “We would expect the difference in 4.5 to be similar to the experience difference of 4 to 3.5,” says Glaese. For the user, prompts related to subjects like writing or programming may yield stronger results, with the back-and-forth interactions feeling more “natural” overall. She hopes all of the chats from this limited release will help them to better understand what GPT-4.5 excels at, as well as its limitations.

Unlike those released as part of OpenAI’s “o” series, GPT-4.5 is not considered to be a reasoning model. The company’s CEO, Sam Altman, posted on social media earlier in February that OpenAI would “ship GPT-4.5, the model we called Orion internally, as our last non-chain-of-thought model.” Nick Ryder, who leads the company’s foundations-in-research team, clarified that this statement pertained to streamlining OpenAI’s product road map, not its research road map. The startup is not just looking into reasoning models, but users can expect to see a more blended experience overall with future releases for ChatGPT where you don’t have to pick which one to use.