OpenAI is removing GPT-4.5 from ChatGPT on June 27, 2026, after a 30-day sunset window that began in late May. For the vast majority of users, this change will be invisible. However, creative writers who relied on the model's distinctive voice and developers who built custom workflows around it will need to take specific steps before the deadline.

Why Is OpenAI Retiring GPT-4.5 Right Now?

This retirement is part of OpenAI's regular model housekeeping throughout 2026. The company has already removed GPT-5.2 from the lineup on June 12, and the older o3 model is scheduled for retirement on August 26. OpenAI says the decision comes down to two practical reasons: GPT-5.5 now outperforms GPT-4.5 across the board, and maintaining multiple overlapping models creates unnecessary complexity and expense in the model picker interface.

It's important to note that this retirement applies only to ChatGPT's web and mobile app interfaces. If you're using GPT-4.5 through OpenAI's API (Application Programming Interface, the technical interface developers use to integrate models into their own applications), that's on a separate timeline with its own retirement schedule. The June 27 deadline affects only the model selector you see when you open ChatGPT.

What Model Replaces GPT-4.5?

GPT-5.5, specifically GPT-5.5 Instant, is the replacement. In fact, if you've been using ChatGPT without manually selecting a model from the dropdown menu, you've already been running on GPT-5.5 Instant since May 5, 2026. The model is fast, handles everyday questions well, and includes web connectivity. More importantly for users concerned about tone, OpenAI spent the spring tuning GPT-5.5 to write in a more natural, less stiff style. The team specifically worked on making it sound warmer and less robotic, partly in response to complaints that newer models had lost the personality of older versions.

Will Your Saved Conversations Disappear?

No. Your existing chat history remains intact and readable. When OpenAI retires a model, your saved conversations keep their full history. You can still scroll back and read everything you discussed with GPT-4.5. What changes is that any new messages you send in those old conversations will run on the current default model instead of the retired one. When GPT-5.2 was pulled on June 12, OpenAI quietly migrated those conversations to GPT-5.5, and the same process will happen with GPT-4.5.

Who Actually Needs to Take Action Before June 27?

The impact varies significantly depending on how you use ChatGPT. Here's what different user groups should do:

• Default users: If you only ever use ChatGPT without touching the model dropdown, you've been on GPT-5.5 since May and need to do nothing. June 27 is a non-event for you.
• Free account holders: Free users run on GPT-5.5 Instant by default and were never able to select GPT-4.5 in the first place, so nothing changes for your account.
• Creative writers: This group genuinely feels the loss. Writers and content creators who loved GPT-4.5's tone and voice should test GPT-5.5 with a specific prompt before the deadline. Instead of relying on the model's built-in voice, you can paste two or three paragraphs of writing you like and instruct the model to match that tone, style, and voice. Models respond to this approach far more effectively than most people expect.
• Custom GPT and workflow builders: If you created a custom GPT or built a workflow around GPT-4.5, check it before June 27, not after. Open the tool, look at the model setting, and switch it to GPT-5.5. Then run your usual prompt once and review the output to see if adjustments are needed.
• Enterprise and team plan users: If you're on a Team, Enterprise, or Education plan, your workspace administrator may have access to legacy-access toggles that consumer accounts don't receive. Check with whoever manages your workspace if a specific model is baked into a process you can't easily change.

How to Prepare Your Workflows for the Transition

If you depend on GPT-4.5 for specific tasks, here are the steps to take before the deadline:

• Test your custom GPTs: Open each custom GPT you've created and switch the model setting from GPT-4.5 to GPT-5.5. Run a test prompt and compare the output to what you're used to getting. Most workflows transfer smoothly without modification.
• Create tone-matching prompts: For creative work, develop a prompt that describes the exact voice and style you want. Include sample text if possible. This becomes your new baseline instruction that you can reuse across conversations.
• Document your settings: If you have complex workflows or automations, write down the exact model settings, prompt structure, and any special instructions you're using. This makes it easier to troubleshoot if GPT-5.5 produces different results.
• Plan for re-tuning: Accept that GPT-5.5 is not GPT-4.5 with a new label. The tone is genuinely different. If you had a workflow tuned to GPT-4.5's exact quirks, you'll need to re-tune it with adjusted prompts or instructions.

What You Can't Get Back After June 27

There are a few honest limitations worth understanding. GPT-5.5 is not GPT-4.5 with a cosmetic update. The underlying model is different, and the tone and writing style reflect that difference. If you had a workflow finely tuned to GPT-4.5's exact characteristics, you won't be able to replicate it perfectly with GPT-5.5 alone. A prompt adjustment gets you close, but not identical.

You also cannot access GPT-4.5 after June 27 through ChatGPT's interface. There's no hidden setting, no legacy mode button, and no way to bring it back for regular users. Once the deadline passes, it's gone from the consumer product. Additionally, switching to GPT-5.5 won't solve the broader frustration some users have with ChatGPT's model picker itself. The interface still offers many options: Instant, Medium, High, Extra High, Pro, and others. Retiring GPT-4.5 does make the list slightly shorter, which is a small improvement, but the underlying complexity remains.

The Bottom Line for Most Users

For approximately 90% of ChatGPT users, June 27 changes nothing. You're already on GPT-5.5 and you'll never notice the transition. For the writers and workflow builders who genuinely preferred GPT-4.5, spend ten minutes this week testing your custom GPTs and saving a tone-matching prompt. This small investment prevents you from depending on whichever model happens to be the default next month, because as OpenAI's pattern shows, there's always another retirement coming.