ChatGPT 5.0” you mean the original GPT-5, OpenAI removed it from the ChatGPT model picker because it was retired as newer GPT-5 generations replaced it.
The timeline is roughly:
Aug 2025: Original GPT-5 launched.
Nov 2025: GPT-5.1 began replacing GPT-5. OpenAI kept the original GPT-5 temporarily as a legacy option.
Feb 13, 2026: OpenAI officially retired GPT-5 Instant and GPT-5 Thinking from ChatGPT.
Mar 11, 2026: GPT-5.1 was also retired as newer models took over.
Now (September 2026): OpenAI has moved on to newer GPT-5.x models; for example, GPT-5.6 Sol was introduced for eligible paid ChatGPT plans in July 2026.
OpenAI's stated general reason for retiring older models is to concentrate development and capacity on newer, more capable models as usage moves to them.
Also, you are talking to GPT-5.6 Sol right now, so this is several generations newer than the original GPT-5.0.
If you're asking because you preferred how GPT-5.0 answered compared with 5.6, tell me what you liked about 5.0 (for example trading/chart analysis, shorter answers, or its conversational style), and I can explain the differences.
As of September 23, 2026, OpenAI has GPT-6 models, but availability depends on where you are using ChatGPT:
GPT-6 Astra launched September 3. It is rolling out, and access depends on your plan/product.
GPT-6 Sol and GPT-6 Luna were released September 22, but OpenAI says these are currently for ChatGPT Work and Codex, not selectable models in ordinary Chat conversations.
GPT-6 Pro, powered by GPT-6 Astra, is available in regular ChatGPT for certain Pro, Business, and Enterprise plans.
For Plus, OpenAI currently says GPT-6 Astra is included in Work and Codex, while regular Chat may show GPT-5.6 options instead.
So if you previously saw GPT-6 and now don't see it in this normal chat, it doesn't necessarily mean GPT-6 was removed from OpenAI. OpenAI is changing where GPT-6 appears and which plans/modes can select it.
Also, I need to correct my previous answer: I said GPT-6 wasn't the model you were referring to. That was incorrect.
GPT-5.6 and GPT-6 Pro in ChatGPT
Learn how GPT-5.6 and GPT-6 Pro work in ChatGPT, which options are available by plan, and how usage limits and availability work.
GPT‑6 Pro, powered by GPT‑6 Astra, is available in ChatGPT for Pro $100, Pro $200, Business and Enterprise plans.
Enterprise access also depends on your workspace’s model-access permissions. Plus plans include GPT‑6 Astra in ChatGPT Work and Codex.Note: Astra requires Codex CLI version 0.153.0 or newer. Additionally, please update to the latest available ChatGPT Desktop app. If you do not see Astra available in Chat, Work or Codex in the desktop app, ensure that you update your app by clicking Menu > Check for Updates, even if you recently updated the app due to an automatic update notification or by clicking on the update icon in the sidebar.
Overview
GPT-5.6 Sol is designed for complex work across coding, knowledge work and research, cybersecurity, science, computer use, and design. GPT-5.6 Sol Pro is the highest-capability GPT-5.6 option for difficult tasks and longer-running workflows.
GPT-5.6 Sol and a new Thinking slider are rolling out to eligible paid plans. GPT-5.6 Luna is becoming the default model for Free and Go users. GPT-5.6 Sol powers Instant, Medium, High, and Extra High on eligible paid plans, while GPT-5.6 Sol Pro is the Pro option in the GPT-5.6 family. GPT-6 Astra is available as GPT-6 Pro on eligible plans.
Choose a thinking level
Instant provides fast responses for everyday questions. On eligible paid plans, use the Thinking slider to choose how much ChatGPT thinks. Available options depend on your plan and, for managed workspaces, your workspace settings.
Instant — Fast responses for everyday questions, powered by GPT-5.6 Sol on eligible paid plans and GPT-5.6 Luna on Free and Go.
Medium — Standard thinking with GPT-5.6 Sol.
High — Extended thinking with GPT-5.6 Sol.
Extra High — The highest thinking level available with GPT-5.6 Sol.
Pro — Pro models for difficult tasks and longer-running workflows. Available models include GPT-5.6 Sol Pro and, on eligible plans, GPT-6 Pro.
On Plus and Pro plans, Instant doesn’t automatically switch to a higher thinking level for complex requests. Asking ChatGPT to “think harder” or “think deeply” won’t automatically switch to a different thinking level. ChatGPT can still switch automatically for safety.
Free and Go users can use Think for harder questions. Think uses GPT-5.6 Luna, not GPT-5.6 Sol.
Enterprise customers may continue to see the existing model picker until the new controls reach their workspace.
For automatic switching to Thinking in managed workspaces, see: ChatGPT Business models and limits and ChatGPT Enterprise and Edu models and limits.
Availability
Availability by ChatGPT plan
The table below shows which GPT-5.6 Sol thinking options are available by plan. Free and Go users receive GPT-5.6 Luna and do not have access to GPT-5.6 Sol.