OpenAI Rolls Out Updated GPT-5.6 Sol to ChatGPT Plus and Pro Users
OpenAI has released an updated version of its flagship GPT-5.6 Sol model for everyday chats, now powering both Instant and deep reasoning for ChatGPT Plus and Pro users. Additionally, free and Go users will gain unlimited access to the GPT-5.6 Luna model starting tomorrow. This update streamlines the user experience by consolidating paid chats under a single, more capable model that significantly reduces factual errors. It also raises the baseline capability for free users by upgrading them to the newer GPT-5.6 Luna model. In high-stakes evaluations covering finance, medicine, and law, the updated GPT-5.6 Sol produced 68% fewer factual errors compared to GPT-5.5 Instant. The model is currently optimized for the Chat experience in ChatGPT and includes a new slider interface.
## BACKGROUND
Released in July 2026, GPT-5.6 is OpenAI's large language model family consisting of three tiers: Luna (fastest and most affordable), Terra (mid-tier), and Sol (the flagship, most capable model). These models are designed to scale capabilities across enterprise work, coding, and scientific research.