GPT-4.5 Released as a Research Preview

OpenAI releases a research preview of GPT-4.5, its largest and best model for chat, scaling up unsupervised learning rather than reasoning.

OpenAI released GPT-4.5 (codename Orion) as a research preview on 27 February 2025, first to ChatGPT Pro ($200 a month) users and developers, with Plus and Team the following week and Edu and Enterprise after that^[1][2][3]
Sam Altman called it 'a giant, expensive model', said it would not be state of the art on benchmarks, and that OpenAI was out of GPUs and would add tens of thousands before the Plus rollout^[2][3]
Reception called it an incremental upgrade and the last OpenAI chatbot without chain-of-thought reasoning^[2]
Later: API access ended on 14 July 2025 in favour of GPT-4.1; it was removed from Plus and Team when GPT-5 launched (7 August 2025), and ChatGPT retirement was set for 27 June 2026^[1][2]

It is a general-purpose model trained mainly by scaling unsupervised learning plus supervised fine-tuning and RLHF; OpenAI said it feels more natural and presents inaccurate information less often than GPT-4o and o1 in one test^[2][3]
It was trained on Microsoft Azure AI supercomputers by scaling up compute and data, and does not think before it responds, unlike reasoning models such as o1 and o3-mini^[4]
OpenAI reports 62.5% accuracy on the SimpleQA factuality benchmark with a 37.1% hallucination rate, and human testers preferring it over GPT-4o on 56.8% to 63.2% of queries^[4]
In ChatGPT it has search, file and image uploads and canvas but no Voice Mode, video or screensharing; in the API it supports function calling, Structured Outputs, streaming, system messages and image input^[4]
API pricing at launch was $75 per million input and $150 per million output tokens, against $2.50 and $10 for GPT-4o; it was also offered in preview through Microsoft's Azure AI Foundry^[2][3]

参考资料 4可信度 87%

第一项始终是图钉的来源。总体可信度是各份资料对上方所用开始和结束时间支持程度的加权平均；资料每比最新的一份旧 180 天，权重减半。

[1]95%
OpenAI Model Release Notes: Introducing GPT-4.5 (February, 27, 2025)
help.openai.com· 发布于 2026年9月19日· 开始 2025年2月27日· 占评分 45%
OpenAI's own model release notes date this entry February, 27, 2025
[2]80%
GPT-4.5 - Wikipedia
en.wikipedia.org· 添加于 2026年9月19日· 占评分 45%
States GPT-4.5 (Orion) was officially released February 27, 2025 to Plus and Pro.^[1]
[3]85%
OpenAI launching GPT-4.5, its next general-purpose large language model
cnbc.com· 发表于 2025年2月27日· 占评分 5%
CNBC report published on launch day about GPT-4.5 rollout.
[4]88%
Introducing GPT-4.5 | OpenAI (Wayback Machine copy)
web.archive.org· 发表于 2025年2月27日· 占评分 5%
Archived copy of OpenAI's^[1] GPT-4.5 announcement, which says it "was trained on Microsoft Azure AI supercomputers", gives SimpleQA accuracy of 62.5% and hallucination rate of 37.1%, and lists search, file and image uploads and canvas but not Voice Mode.

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