openai/gpt-6.1-terraGPT-6.1 Terra is OpenAI's cost-efficient middle-tier model in the GPT-6.1 series, released October 26, 2026 as the replacement for GPT-5.6 Terra at 50% lower standard prices. It is built for visual reasoning, precise computer use, coding, and clear, natural writing, accepting text and images and returning text. It has a 1,050,000-token context window (up to 922K input), up to 128,000 output tokens, and a June 1, 2026 knowledge cutoff. Reasoning effort accepts none, low, medium (default), high, xhigh, or max. Fast service tier is available. Tool calling requires the Responses API.