GPT-5.6 Terra

GPT-5.6 Terra occupies the middle ground of OpenAI's three-tier GPT-5.6 family — strong enough for serious coding, analysis, and content generation but at half the cost of Sol. It shares the same 1M+ context window and 128K output limit. For most production applications, Terra is the right starting point: try it first and only move to Sol if you hit quality ceilings on your hardest prompts. At $2.50/$15 per million tokens, it undercuts GPT-5.5 significantly while matching or exceeding its performance.