OpenAI is expanding the GPT-6 family with GPT-6 Sol and GPT-6 Luna, two faster and more affordable models aimed at professional work, coding and agentic tasks. They join GPT-6 Astra, which remains the company’s most capable option for demanding projects. OpenAI says Sol and Luna carry forward advances in factuality, computer use, alignment and communication.
OpenAI says caching and inference gains have cut API prices by 50% compared with GPT-5.6 promotional pricing. Per million tokens, Sol costs $2 for input and $10 for output, while Luna costs $0.10 for input and $0.50 for output. The lower prices are intended to give users more room to iterate without moving every task to Astra.
On AutomationBench, GPT-6 Sol at xhigh effort scored 33.2% at $0.27 per task. That topped GPT-6 Astra at low effort and Claude Opus 5 at max effort, both at far higher cost. On Agents’ Last Exam, Sol reached 56.4% at max effort, above Opus 5’s highest score in the evaluation at 60% lower cost per task. Luna at high effort gained 5.4 percentage points over its predecessor while cutting task cost by 58%.
OpenAI also reports that Sol made roughly half as many factual mistakes as its predecessor in an internal test based on conversations flagged for errors, though the test cases were not representative of normal usage or controlled for answer length. In coding, Sol scored 68.8% on DeepSWE v1.1, within 1.1 points of Claude Fable 5’s top result at roughly 80% lower cost per task. Astra still leads OpenAI’s computer-use lineup.
Prompt caching is a central part of the release. Cached input reads receive a 90% discount, while new dashboards and diagnostics help developers monitor reuse and explain misses. GitHub says the changes reduced prompt tokens needing fresh processing by more than half across billions of requests. OpenAI also expects clearer, slightly shorter technical responses and fewer misleading claims about completed coding work.
GPT-6 Sol and Luna are rolling out today in ChatGPT Work and Codex for Plus, Pro, Business, Enterprise and Edu users. Free and Go users can access Luna in the desktop app. Neither model is yet available in Chat. API model identifiers are gpt-6-sol and gpt-6-luna.