OpenAI Launches GPT-6 Sol and Luna, Cutting API Prices 50% Below Predecessors

OpenAI on Sept. 22 released GPT-6 Sol and GPT-6 Luna, expanding its GPT-6 lineup and halving API pricing versus promotional rates for GPT-5.6 Sol and Luna. GPT-6 Sol is priced at $2 per million input tokens and $10 per million output tokens; GPT-6 Luna costs $0.1 per million input tokens and $0.5 per million output tokens. OpenAI attributed the cuts to improved caching and inference efficiency, with cached input tokens discounted as much as 90%. Sol targets coding, workflow automation and complex professional tasks; Luna handles document summarization and information extraction. Both inherit capabilities from flagship GPT-6 Astra, which remains OpenAI's most capable model for difficult projects. OpenAI said Sol outperformed Anthropic's Claude Opus 5 on AutomationBench workflow tests at 9% of the cost per task. Both models are available to Plus, Pro, Business, Enterprise and Education users on ChatGPT Work and Codex. The launch came roughly 90 minutes after Anthropic introduced Claude Opus 5.5.