GPT-4.5 (codenamed "Orion") is a

large language model A large language model (LLM) is a language model trained with self-supervised machine learning on a vast amount of text, designed for natural language processing tasks, especially language generation. The largest and most capable LLMs are g ...

developed by

OpenAI OpenAI, Inc. is an American artificial intelligence (AI) organization founded in December 2015 and headquartered in San Francisco, California. It aims to develop "safe and beneficial" artificial general intelligence (AGI), which it defines ...

as part of the GPT series. Officially released on February 27, 2025, GPT-4.5 is available to users subscribed to the

ChatGPT ChatGPT is a generative artificial intelligence chatbot developed by OpenAI and released on November 30, 2022. It uses large language models (LLMs) such as GPT-4o as well as other Multimodal learning, multimodal models to create human-like re ...

Plus and Pro plans across web, mobile, and desktop platforms. Access is also provided through the OpenAI

API An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...

and the OpenAI Developer Playground, but the company plans to phase out API access to the model in July.

Overview

GPT-4.5 was primarily trained using

unsupervised learning Unsupervised learning is a framework in machine learning where, in contrast to supervised learning, algorithms learn patterns exclusively from unlabeled data. Other frameworks in the spectrum of supervisions include weak- or semi-supervision, wh ...

, which improves its ability to recognize patterns, draw connections, and generate creative insights without reasoning. This method was combined with supervised fine-tuning and reinforcement learning from human feedback. The computational resources needed for training were provided by

Microsoft Azure Microsoft Azure, or just Azure ( /ˈæʒər, ˈeɪʒər/ ''AZH-ər, AY-zhər'', UK also /ˈæzjʊər, ˈeɪzjʊər/ ''AZ-ure, AY-zure''), is the cloud computing platform developed by Microsoft. It has management, access and development of ...

Sam Altman Samuel Harris Altman (born April 22, 1985) is an American technology entrepreneur, investor, and the chief executive officer of OpenAI since 2019 (he was Removal of Sam Altman from OpenAI, briefly dismissed and reinstated in November 2023). He ...

described GPT-4.5 as a "giant, expensive model". As of February 2025, through OpenAI's API it costs $75 per million input tokens and $150 per million output tokens, whereas

GPT-4o GPT-4o ("o" for "omni") is a multilingual, multimodal generative pre-trained transformer developed by OpenAI and released in May 2024. It can process and generate text, images and audio. GPT-4o is free, but ChatGPT Plus subscribers have higher ...

only costs $2.50 per million input tokens and $10 per million output tokens. The model was tested on the MMLU test set, which tested 15 different languages, namely

Arabic Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...

, Bengali, Chinese, English, French,

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

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, Indonesian,

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...

, Japanese,

Korean Korean may refer to: People and culture * Koreans, people from the Korean peninsula or of Korean descent * Korean culture * Korean language **Korean alphabet, known as Hangul or Korean **Korean dialects **See also: North–South differences in t ...

, Portuguese,

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many countries in the Americas **Spanish cuisine **Spanish history **Spanish culture ...

, Swahili, and Yoruba, with the model outperforming GPT-4o on all of them. A pre-print study in March 2025 found that GPT-4.5 passed the

Turing test The Turing test, originally called the imitation game by Alan Turing in 1949,. Turing wrote about the ‘imitation game’ centrally and extensively throughout his 1950 text, but apparently retired the term thereafter. He referred to ‘ iste ...

. In April 2025, OpenAI announced that it was phasing out GPT-4.5 from API access in favor of GPT-4.1, set to take effect on July 14.

Reception

GPT-4.5 was mostly seen by reviewers as an incremental upgrade over

. Cade Metz, writing for ''

The New York Times ''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of ...

'', stated that the model "signifies the end of an era" and was "unlikely to generate as much excitement as GPT-4". Eric Schwartz from ''

TechRadar ''TechRadar'' is an online technology publication owned by Future plc. It has editorial teams in the United States, United Kingdom, and Australia that provide news and reviews of tech products and gadgets. It was launched in 2008 and expanded t ...

'' praised its ability to understand subtext and respond to questions in a more humanlike manner compared to GPT-4o, but concluded that "it doesn't feel like an enormous leap" from the prior model. Aaron Levie, the CEO of cloud services company

Box A box (plural: boxes) is a container with rigid sides used for the storage or transportation of its contents. Most boxes have flat, parallel, rectangular sides (typically rectangular prisms). Boxes can be very small (like a matchbox) or v ...

, told ''Axios'' that GPT-4.5 is "about 20% better" than GPT-4o on specific tasks, such as information extraction in large datasets.

References

External links

* {{AI-stub Large language models 2025 software Generative pre-trained transformers ChatGPT 2025 in artificial intelligence