GPT-6 Sol and GPT-6 Luna

The two lower tiers of OpenAI's GPT-6 generation, released together on September 22 below GPT-6 Astra. GPT-6 Sol is "built to power complex coding and agentic workflows" at $2 / $10 per million input/output tokens; GPT-6 Luna is OpenAI's most efficient model at $0.10 / $0.50. Both take text and image input with a 1.05M-token context and 128K output, and support reasoning efforts from none to max. The prices are half those of the GPT-5.6 Sol and Luna tiers, and there is no GPT-6 Terra: OpenAI's model list runs Astra, Sol and Luna. Luna is also offered to ChatGPT Free and Go users. Artificial Analysis scores Sol 48 on Intelligence Index v4.3.2 at max effort, one point above GPT-5.6 Sol, and Luna 37, level with GPT-5.6 Luna. Under its Preparedness Framework OpenAI treats both as High capability in cybersecurity and in biological and chemical risk, but below the High threshold for AI self-improvement. Seven days later GPT-6.1 Sol arrived, and the GPT-6 Sol docs now point to it as the newer Sol model. Parameters undisclosed.