GPT-6 Luna

OpenAI's most efficient GPT-6 model for high-volume, low-cost tasks like summarizing, extracting, and quick Q&A.

OpenAI · Frontier/foundation models · model

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Overview

GPT-6 Luna is OpenAI's cheapest GPT-6 model, positioned for high-volume tasks with a clear goal such as summarizing documents, extracting information, or answering quick questions. It shares GPT-6 Sol's 1,050,000-token context window and 128,000-token max output, but with a May 18, 2026 knowledge cutoff and pricing an order of magnitude lower. It launched alongside GPT-6 Sol on September 22, 2026, available in ChatGPT Work, Codex, and the API for most paid accounts, plus the desktop app and Free/Go tiers. On October 8, 2026, OpenAI began rolling out GPT-6's "Intelligent UI" to render tappable buttons, custom calculators, and editable graphs inline in chat instead of plain text; Pro, Plus, Business, and Enterprise got it immediately, with Free and Go tiers (running GPT-6 Luna) following that Thursday globally.

This is a sourced directory entry. Features and capabilities are reported in the linked sources; this entry does not document independent Aymorphic testing.

Key features

  • 1,050,000-token context window, 128,000 max output tokens
  • Lowest-cost model in the GPT-6 lineup at launch
  • Supports streaming, structured outputs, function calling, file search, image input, web search, and prompt caching
  • Responses API tool support: web search, file search, image generation, code interpreter, computer use, hosted shell
  • Available to Free and Go ChatGPT tiers, not just paid plans
  • "Intelligent UI" (Oct 8, 2026): renders tappable buttons, custom calculators, and editable graphs inline instead of plain text

Use cases

  • High-volume document summarization and information extraction
  • Quick question-answering at low per-token cost
  • Free-tier and desktop-app ChatGPT usage
  • Lightweight agentic steps where Sol/Astra-level reasoning isn't needed

Pricing

$0.10/million input tokens, $0.50/million output, $0.01/million cached input, $0.125/million cache writes (rates double above 272K input tokens).

Pricing reflects the source record and may change. Confirm current terms with the provider.

Dates and sources

Released
22 Sept 2026
Record updated
10 Oct 2026
Record last checked
10 Oct 2026

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