Chat Smith has added GPT-6 Luna to its model lineup — the fastest and most cost-efficient tier of OpenAI's GPT-6 generation, built for focused, high-volume work, available now for all Chat Smith Pro users at no extra cost.
OpenAI released GPT-6 Luna on September 22, 2026 alongside GPT-6 Sol. Where Sol handles demanding reasoning, Luna is aimed at high-volume tasks with a clear goal — summarizing documents, extracting information, answering quick questions. It carries the same 1,050,000-token context window as the rest of the generation, accepts text and image input, and its knowledge cutoff of May 18, 2026 is the most recent in the family.
What makes GPT-6 Luna stand out
Built for repetition, priced for it. OpenAI halved Luna's API pricing against its predecessor, to $0.10 per million input tokens and $0.50 per million output. On AutomationBench, a test of business workflows across 47 tools, Luna at high effort improves on GPT-5.6 Luna by 5.4 percentage points while costing 58% less per task — better results and a lower bill at the same time.
Coding well above its tier. On DeepSWE v1.1, which sets long-horizon software engineering tasks in real repositories, Luna at max effort scores 66.6% — comparable to Claude Opus 5 and Claude Fable 5 at medium effort, while costing 93% less per task than Opus 5. For a model positioned as the cheap tier, that is an unusual place to land.
Factuality that reaches the previous flagship tier. OpenAI's internal factuality evaluation is built from de-identified real conversations where users flagged an error from an earlier model. At higher effort levels, Luna matches GPT-5.6 Sol on that set — at roughly a hundredth of Sol's cost.
A clearer way of answering. Luna inherits the collaboration style introduced earlier in the GPT-6 generation — less jargon, fewer low-value details, slightly shorter answers without losing substance — which OpenAI expects to be most noticeable in technical and coding conversations. Alignment improved too: Luna shows lower rates of misleading claims about its own coding work than its predecessor.
Included in Chat Smith Pro — no extra cost
GPT-6 Luna is available immediately to all Chat Smith Pro subscribers. No upgrade, no additional charge — open the model picker and select GPT-6 Luna to get started.
Chat Smith's goal is to bring the best available AI models into one place, so users can put Luna side by side with Claude Sonnet 5 or Grok 4.5 and pick the right tool for each task without switching platforms.
GPT-6 Luna is available now for all Chat Smith Pro users at https://chatsmith.io/model/gpt-6-luna.
