It is available now to Plus, Pro, Enterprise, and Edu users in ChatGPT Work and Codex, and through the OpenAI API as gpt-6.1-terra.
Standard API pricing is $1 per million input tokens, $0.05 per million cached input tokens, and $5 per million output tokens. OpenAI says these prices are 50% below GPT-5.6 Terra and GPT-6.1 Sol. The company says the same ChatGPT Work and Codex usage allowance covers more tasks with Terra than with GPT-5.6 Terra.
OpenAI reports a 15-percentage-point gain over GPT-5.6 Terra on Agents' Last Exam at medium reasoning effort, at about one-third the cost. It also reports a 50.3% score on Terminal-Bench 4.0 at maximum reasoning effort, compared with GPT-5.6 Terra's published 21.5% score. These are OpenAI-reported evaluations; the announcement does not establish independent benchmark replication, real-world task completion rates, or the exact usage allowance for each plan.