Decoding OpenAI's GPT-6 Family: Astra vs. Sol vs. Luna
Navigating OpenAI's latest AI lineup requires understanding the specific strengths and costs of each tier. While GPT-6 Astra remains the flagship model for the most demanding tasks, the new Sol and Luna models offer targeted balances of speed, cost, and near-flagship intelligence for everyday users and enterprise workflows alike.
Decoding OpenAI's GPT-6 Family: Astra vs. Sol vs. Luna
OpenAI's GPT-6 series operates as a tiered family of models, each engineered for a specific balance of capability, speed, and cost. Knowing which model sits behind your plan—and which to select for specific workflows—is critical for optimizing both performance and budget.
GPT-6 Astra: The Flagship
Astra is OpenAI's most capable model, designed to deliver the highest intelligence and best results. It is built to handle the hardest reasoning work and complex research tasks.
Astra powers the Pro reasoning option, Dots, and the Ultrafast tier.
GPT-6.1 Sol: Near-Astra Intelligence at Lower Cost
Introduced in late September 2026, GPT-6.1 Sol is an upgrade over the base Sol model, offering near-flagship performance across complex professional tasks and business workflows.
The model comes close to Astra on most professional work but operates at just one-fifth of the token price.
In computer use tests (OSWorld 2.0 offline), it scored within 2.1 percentage points of Astra at maximum effort, while costing roughly one-seventh per task.
It features heavily discounted prompt caching, charging just $0.10 per million cached tokens—95% below the standard input price—making it highly efficient for AI agents that repeatedly read long documents.
It is specifically recommended for complex coding, research, and computer use.
GPT-6 Sol: The Everyday Paid Model
The standard GPT-6 Sol is the everyday conversational model powering ChatGPT's Chat tab for paying subscribers.
It serves as the default model for Plus, Pro, Business, and Enterprise plans as of October 7, 2026.
GPT-6 Luna: Fast Work at Scale
Luna is the lightest and most efficient model in the GPT-6 family. It is engineered for fast, high-volume, and repeatable everyday work.
It excels at focused tasks with clear goals, such as extracting invoice fields, classifying requests, or generating structured summaries.
GPT-6 Luna is the core model currently provided to users on the Free and Go plans in ChatGPT.
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