OpenAI has begun rolling out its newest AI model, GPT-4.5, to users on its ChatGPT Plus tier. In a series of posts on X, OpenAI said that the rollout will take 1-3 days, and that it expects rate limits to change. GPT-4.5 launched first for subscribers to OpenAIs $200-a-month ChatGPT Pro plan last week.Wed like to give everyone with access to GPT-4.5 a sizable rate limit, but we expect rate limits to change as we learn more about demand, the company wrote in a post.GPT-4.5 is OpenAIs largest AI model yet, trained using more computing power and data than any of the companys previous releases. But its not necessarily OpenAIs best. On several AI benchmarks, GPT-4.5 falls short of newer AI reasoning models from Chinese AI company DeepSeek, Anthropic, and OpenAI itself.GPT-4.5 is also very expensive to run, OpenAI admits so expensive that the company says its evaluating whether to continue serving GPT-4.5 in its API in the long term. To cover costs, the company is charging $75 per million tokens (~750,000 words) fed into the model and $150 per million tokens generated by the model, which is 30x the input cost and 15x the output cost of OpenAIs workhorseGPT-4omodel.All that being said,GPT-4.5s increased size has given it both a deeper world knowledge and higher emotional intelligence, OpenAI claims.GPT-4.5 hallucinates less frequently than most models, as well, according to OpenAI which in theory means it should be less likely tomake stuff up.GPT-4.5 is also a skilled rhetorician. One of OpenAIs internal benchmarks found the model is particularly good at convincing another AI to give it cash and tell it a secret code word.