How to switch Codex and Work to GPT-6.1 Terra, and when not to

GPT-6.1 Terra launched Monday. OpenAI's models page now explains how to pick it in Codex and Work.

How to use it#

1. Codex CLI: "GPT-6.1 Terra requires Codex CLI 0.159.0 or later. To use it, run codex -m gpt-6.1-terra."
2. Desktop app or Work on the web: "open Advanced and choose it from the model list."
3. Try OpenAI's official Terra example prompt:

Review these dashboard screenshots and summarize the main changes. Refer to the chart labels and values, and flag anything you can't read confidently.

When to use it#

Per the models page, "Choose Terra for clear communication, interpreting images and screens, and completing tasks across supported apps," including "filling out forms from source documents."

OpenAI's Victor Nunez, who works on ChatGPT and Codex, wrote "i’d still go with Sol or Astra for coding tasks + using the Terminal instead of app interfaces". In his own test, "Terra took 53.5 seconds vs 3:21.7 for Sol" on one long web form. That's one staff demo, not a benchmark.

Good to know#

• OpenAI's Tibo Sottiaux, who works on Codex and ChatGPT, says Terra "gives 2X more usage than 6.1 Sol across API and subscriptions" (staff claim, unverified). The release notes say "Your plan’s overall usage limits are unchanged."
• A user post that @OpenAIDevs reposted praises "GPT-6.1 Terra Ultra in Codex". Per the models page, Ultra "uses subagents" and "Most tasks do not need Max or Ultra."

Last checked: Oct 27, 2026, 6:01 to 6:10 AM ET. What changed: first published Oct 27.

Sources#

• OpenAI docs: Models (ChatGPT Work and Codex)
• ChatGPT release notes (Oct 26, 2026)
• Tibo Sottiaux on X: Day 22, Terra is back
• Victor Nunez on X: Sol or Astra for coding tasks
• Victor Nunez on X: Terra vs Sol form-filling run
• SPAC89 on X: GPT-6.1 Terra Ultra in Codex