OpenAI launches GPT-6 Sol and GPT-6 Luna at half the price of GPT-5.6
Confirmed
Importance: major (4 of 5)Status
- Claim
Confirmed
- Our reporting
- High confidence
- Importance
- Major (4 of 5)
- Last verified
- 30 September 2026
Your AI and this story
- GPT-6 Astra145 days after its cutoff
- Claude Opus 5.584 days after its cutoff
- Gemini 4 Hydrogen175 days after its cutoff
- Grok 4.7114 days after its cutoff
None of these four assistants can know about it. The closest, Claude Opus 5.5, stops 84 days before it.
Key facts
- Released Sept 22, 2026 in ChatGPT Work, Codex and the API
- Plus, Pro, Business, Enterprise and Edu get both models; Free and Go users get GPT-6 Luna in the desktop app
- GPT-6 Sol API: $2 input / $10 output per 1M tokens, cached input $0.20 (OpenAI compared against $4/$20 for GPT-5.6 Sol)
- GPT-6 Luna API: $0.10 input / $0.50 output per 1M tokens, cached input $0.01 (vs $0.20/$1.20 for GPT-5.6 Luna)
- Price cut attributed to caching and inference improvements
- Sol: about half the factual mistakes of GPT-5.6 Sol on OpenAI’s internal factuality eval
- Agents’ Last Exam: Sol 56.4% (~95% of Astra’s top score)
- DeepSWE v1.1: Sol 68.8%, Luna 66.6%; OSWorld 2.0 Offline: Sol 60.5%, Luna 58.1%
Show 3 more
- AutomationBench 1.0.6: Sol 33.2% (extra-high effort)
- Codex CLI 0.156.1 (Sept 23) added Sol and Luna to its model picker; Codex 0.157.0 (Sept 25) added Amazon Bedrock support for them
- ‘Better prompt caching for GPT-6’ (Sept 22): the GPT-6 family launched with a new caching system with higher default hit rates; cache discounts apply to eligible shared prefixes reused within a 30-minute window; new Prompt Caching Dashboard and a cache-miss diagnostics tool
What happened
OpenAI extended the GPT-6 generation with two cheaper models. GPT-6 Sol targets complex work such as coding; GPT-6 Luna targets “high-volume tasks with a clear goal, like summarizing documents, extracting information, or answering quick questions”. Both were trained with similar methods to GPT-6 Astra. OpenAI: “GPT-6 Astra introduced a new generation of intelligence; these models extend its benefits by making that intelligence more efficient and accessible.” OpenAI also claims both beat Anthropic’s Fable and Opus models on its comparisons.
Why it matters
Frontier-level reliability dropped in price by half within three weeks of the flagship launch, and a GPT-6-class model (Luna) reached free users. This continues the 2026 pattern of rapid price compression across OpenAI’s tiers (see the July 30 GPT-5.6 price cut).
Caveat: OpenAI’s comparison uses $4/$20 for GPT-5.6 Sol, whereas launch-time third-party sources listed GPT-5.6 Sol at $5/$30; the developer-community post refers to “GPT-5.6 promotional pricing”. Context window not confirmed in sources read.
Sources
11 sources from 9 sites. Numbers match the chips in the text.
11 sources: 5 primary, 5 press, 1 reaction
Primary
- Introducing GPT-6 Sol and Luna (OpenAI)openai.com, official
- OpenAI Developer Community announcementcommunity.openai.com, official
- OpenAI on X: ‘Please welcome GPT-6 Sol and GPT-6 Luna’x.com, official
- Sam Altman on X: Sol and Luna at half the pricex.com, official
- OpenAI: Better prompt caching for GPT-6openai.com, official
Press
- TechCrunch: OpenAI launches GPT-6 Sol and Lunatechcrunch.com, press
- The New Stack: OpenAI releases GPT-6 Sol and Luna and cuts token prices in halfthenewstack.io, press
- Vellum: GPT-6 Sol and Luna benchmarks explainedvellum.ai, press
- ZDNet: OpenAI launches GPT-6 Sol and Lunazdnet.com, press
- The Deep View: OpenAI’s cheaper GPT-6 models change the maththedeepview.com, press
Reactions
- Releasebot: OpenAI release notes (Codex versions)releasebot.io, discussion
Changes
- Added OpenAI’s GPT-6 prompt-caching post
- Added ZDNet and Deep View links
- Added post link(s)
- Filed
