OpenAI added two new models to the ChatGPT ecosystem on September 22, 2026, changing how users and developers access artificial intelligence capabilities. The release introduces GPT-6 Sol and GPT-6 Luna, offering distinct performance tiers that affect both daily interaction and API costs. This update matters because it expands access to newer models for free users while significantly lowering prices for developers using the API. Buyers and users should note that access depends heavily on your subscription tier and the platform you use to interact with the service.
Free desktop access and steep API price drops define the update
The GPT-6 family includes Sol and Luna as the primary releases for this update, joining the previously mentioned GPT-6 Astra model in the broader lineup. Sol targets higher accuracy needs, while Luna focuses on cost efficiency for routine tasks. OpenAI made these models available through the API immediately upon release. Desktop and web users access them through specific ChatGPT interfaces rather than a universal rollout across all features.
Pricing for the GPT-6 models reflects a sharp drop in cost for the Luna tier compared to previous generations. The GPT-6 Sol API costs $2 per million input tokens and $10 per million output tokens. The GPT-6 Luna API costs just $0.10 per million input tokens and $0.50 per million output tokens. Cached input receives a 90% discount on API pricing, further reducing costs for repeated queries. These rates apply globally to API users.
OpenAI stated that "Free and Go users can access GPT-6 Luna, but only in the desktop app." The models are also available in Work and Codex for Plus, Pro, Business, Enterprise, and Edu subscribers. However, the models are available in Work and Codex, but not Chat. GPT-6 Sol makes about half as many factual mistakes as GPT-5.6 Sol according to internal measurements. Luna at higher effort settings matches GPT-5.6 Sol at roughly one-hundredth of the cost. None of these performance figures have been independently verified yet.
GPT-6 Luna in the desktop app does not currently include unlimited text chats or the Think button available in the Chat window for GPT-5.6 Luna. OpenAI has not published a usage limit for Luna in the free tier, so nobody knows yet how far the allowance goes. The models are live in the API and available to paid subscribers in Work and Codex. Free users must use the desktop application to access Luna. This release solidifies a two-tier approach to the GPT-6 family for immediate consumer and developer use.
Source: NotebookCheck
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