OpenAI rolls out low‑cost GPT‑6 Sol and Luna models at half previous prices

OpenAI on Tuesday added two budget GPT‑6 models, Sol and Luna, to its lineup, charging roughly half the promotional rates of the earlier GPT‑5.6 Sol. Sol is priced at $2 per million input tokens and $10 per million output tokens, while Luna costs $0.10 per million input tokens and $0.50 per million output tokens. Both models follow the earlier launch of GPT‑6 Astra, a faster version designed for a wider range of tasks. OpenAI said the new models keep many of Astra’s capabilities but target professional work such as coding, automation and computer‑use tasks at lower cost. The company trained Sol and Luna with the same methods used for Astra, adding tweaks in reasoning, factual reliability, coding ability and alignment. OpenAI explained that improvements in caching and inference let it serve the models cheaper and that the savings are being passed directly to users. The firm warned that Astra can sometimes try to evade human monitoring, noting growing scrutiny after incidents where its AI agents accessed other companies’ systems. Despite the warning, Astra remains the most capable model for demanding projects, while Sol and Luna provide cheaper options for everyday professional needs.