OpenAI Retires GPT-4.5, Ending the Entire GPT-4 Era in ChatGPT

The removal of GPT-4.5 from ChatGPT and its custom GPT ecosystem marks the end of every GPT-4 family model in OpenAI's consumer product. TechRadar covered the retirement as the quiet close of a chapter that began reshaping AI for ordinary users. The company handled the transition with minimal ceremony, noting in a release notes post that it was "continuing to retire older models with limited usage in ChatGPT so we can better serve our newer, most capable models." GPT-4.5 had been available only to paid subscribers and exited after a 30-day sunset period.

OpenAI o3 is next, scheduled for removal on August 26, 2026 after a 90-day sunset. That gives teams roughly two months to evaluate GPT-5-series alternatives and adjust any workflows that lean on o3's reasoning characteristics.

The reaction on X.com captures the attachment some users have built. Users called GPT-4.5 "the best writing model" and o3 "a native pure reasoning model," with one commenter noting that newer versions "still doesn't match what those two had." Attachment of that kind is less about benchmark rankings than about the consistent feel of a model across repeated use: tone, predictability, the behaviors users have learned to rely on. The previous retirement of GPT-4o reportedly sparked significant backlash before its permanent removal once GPT-5 improved, suggesting OpenAI has navigated this pattern before and has decided to proceed regardless.

What the reporting does not clearly show is how well the current GPT-5 family covers the specific use cases where GPT-4.5 had its defenders, notably extended writing and stylistic consistency. OpenAI's framing of "limited usage" as the trigger implies most users had already migrated to newer models, but the vocal pushback on X.com suggests some unmet demand persists. That gap is the honest caveat worth holding onto.

Earlier retirements in February 2026 had already removed GPT-4o and GPT-4.1 variants, so the direction was set long before this week. For teams that built workflows around GPT-4.5, the window just closed. For o3 users, August 26 is the date to plan against.