Luna

OpenAI has released GPT-5.6 Luna, a fast and cost-efficient model in its GPT-5.6 series. The model features a 1 million token context window and is priced at $1 per 1M input tokens and $6 per 1M output tokens, with a knowledge cutoff of February 2026.

OpenAI released GPT-5.6 on July 9, 2026, introducing a new three-tier model naming system: Sol (flagship), Terra (balanced for everyday work), and Luna (fast and affordable). The company integrated Codex development workflows directly into the main ChatGPT app and launched ChatGPT Work for enterprise users.