Introducing GPT-6.1 Sol

OpenAI introduced GPT-6.1 Sol and Luna on September 29, 2026, as more cost-efficient alternatives to their predecessors, despite GPT-6 Astra remaining the top model for computer use. GPT-6.1 Sol achieved a 60.5% score on OSWorld 2.0 offline at xhigh effort, comparable to Claude Opus 5 at medium effort (60.3%), but at 80% lower cost. GPT-6.1 Luna (max) surpassed GPT-5.6 Sol (medium) at one-tenth the cost.

This release marks the first time OpenAI has introduced models specifically optimized for cost-efficiency rather than raw performance, unlike previous GPT series updates.