OpenAI's two new GPT-6 models — Sol for complex coding and agentic work, Luna for high-volume tasks — at roughly half the API price of GPT-5.6.
GPT-6 Sol & Luna announcement hero
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What is GPT-6 Sol & Luna?
Frontier AI intelligence, now at half the price
GPT-6 Sol and Luna are OpenAI's two new models in the GPT-6 family, positioned below the flagship GPT-6 Astra and trained with Astra-generation methods. Sol is the mid-tier workhorse for complex coding, debugging, data analysis, and agentic workflows (gpt-6-sol). Luna is the high-volume tier for summarization, extraction, and short answers (gpt-6-luna).
Both offer a 1.05M token context window with 128K max output and text+image inputs. The headline change is price: roughly 50% lower API pricing than GPT-5.6 — Sol at $2 in/$10 out per 1M tokens, Luna at $0.10 in/$0.50 out, with 90% off cached reads. Prompt caching is also improved, with higher hit rates, caches that survive reasoning-effort and tool changes, and a caching dashboard. OpenAI reports Sol makes roughly half the factual errors of GPT-5.6 Sol.
The models are available via API, Codex, and ChatGPT Work (Luna is also free in the ChatGPT desktop app for Free/Go users). Pricing details: developers.openai.com/api/docs/pricing.
Platforms and languages
GPT-6 Sol & Luna Availability
Platforms
Languages
Capabilities
GPT-6 Sol & Luna Key Features
Sol for demanding work
Mid-tier workhorse for complex coding, debugging, data analysis, and agentic workflows.
Luna for scale
High-volume tier for summarization, extraction, and short answers at a fraction of the cost.
Half the API price
About 50% cheaper than GPT-5.6, with 90% off cached reads.
Improved prompt caching
Higher hit rates, caches that survive reasoning-effort and tool changes, plus a caching dashboard.
Long context
1.05M token context window with 128K max output and text+image inputs.
Best for
Who uses GPT-6 Sol & Luna?
Developers and engineering teams
Build agents and coding workflows on cheaper frontier models
Enterprises running high-volume inference
Cut inference costs on summarization, extraction, and short-answer workloads
Plans and access
GPT-6 Sol & Luna Pricing
Freemium
API: Luna $0.10/$0.50 per 1M tokens, Sol $2/$10; 90% off cached reads. Luna free in ChatGPT desktop app.
Common questions
GPT-6 Sol & Luna FAQs
What is the difference between GPT-6 Sol and Luna?
Sol is the mid-tier model for complex coding, debugging, data analysis, and agentic workflows. Luna is the high-volume, lower-cost tier for summarization, extraction, and short answers.
How much do Sol and Luna cost?
API pricing is roughly half of GPT-5.6: Sol costs $2 in/$10 out per 1M tokens, Luna $0.10 in/$0.50 out, with 90% off cached reads. Luna is also free in the ChatGPT desktop app for Free/Go users.
Where can I use Sol and Luna?
They are available via the API, Codex, and ChatGPT Work. Luna is also free in the ChatGPT desktop app for Free and Go users.
What is new about prompt caching?
Caching now has higher hit rates, survives reasoning-effort and tool changes, and comes with a caching dashboard to track savings.
Is Astra still the best model for maximum quality?
Yes — GPT-6 Astra remains the flagship for maximum quality; Sol and Luna trade some capability for much lower cost.
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