o3 disappears from ChatGPT on Wednesday — and keeps selling in the API for another 107 days

On 26 August 2026 OpenAI o3 stops being selectable in ChatGPT. The date was set on 28 May, when OpenAI gave the model a 90-day sunset alongside GPT-4.5, which went on 27 June. Both were paid-tier-only options hidden behind model settings by then. The same announcement contains the sentence that most coverage drops: "These changes apply to ChatGPT only; there are no changes to the API." In the API, o3 is scheduled to shut down on 11 December 2026, together with o3-pro and the whole first generation of GPT-5 — gpt-5, gpt-5-mini, gpt-5-nano and gpt-5-pro. Every one of them is pointed at gpt-5.6-sol. That is 107 days between the two deaths of the same model. The gap can be much wider. GPT-4o was removed from ChatGPT on 13 February 2026 and is still on sale in the API today at $2.50 per million input tokens, with no shutdown date announced at all. Only its oldest snapshot, gpt-4o-2024-05-13, is scheduled to go, on 23 October — and the model's default snapshot has been gpt-4o-2024-08-06 for two years. A model can be gone from the product the public knows and still be a supported production endpoint six months later. That is why the autumn calendar reads differently depending on which side you are on. For consumers, the visible loss is o3 on Wednesday. For anyone shipping software, the dates that matter are 23 October — when gpt-3.5-turbo, gpt-4, gpt-4 Turbo, o1, o1-pro, o3-mini, o4-mini and gpt-image-1 go for good — then 1 December for the older image models, 11 December for o3 and the GPT-5 family, and 20 January 2027 for the legacy audio and realtime line. OpenAI now publishes the notice periods behind those dates: at least six months for generally available models, at least three for specialised variants such as chat or Codex builds, and as little as two weeks for anything with "preview" in its name. It is a commitment about warning time, not about lifespan — and the ChatGPT calendar it does not cover has been the faster of the two all year.