Introducing GPT-6 Sol and Luna

OpenAI introduced GPT-6 Sol and Luna on September 29, 2026, as more cost-efficient alternatives to their predecessors. While GPT-6 Astra remains the top model for computer use, GPT-6 Sol achieves a similar score to Claude Opus 5 on OSWorld 2.0 offline at 80% lower cost. GPT-6 Luna (max) also surpasses GPT-5.6 Sol (medium) at one tenth of its cost, offering significant performance-to-cost improvements.

This report highlights the first time OpenAI has publicly detailed specific cost-performance comparisons against competitor models like Claude Opus 5, rather than just internal benchmarks.