OpenAI Launches GPT‑5.6 Series: Sol, Terra, Luna in Limited Preview
Decision Brief
What changedOpenAI began limited preview of GPT‑5.6 series (Sol, Terra, Luna) with full rollout planned within weeks.
Why it mattersAI builders need to know pricing, performance differences, and caching to evaluate cost and application choices.
Who should careTeams building on model APIs
Affected stackOpenAI
Builder actionEvaluate
Source confidenceMedium · Reliable media or first-hand reporting
OpenAI this week started limited preview of three GPT‑5.6 models: flagship Sol, balanced Terra for daily work, and fast economical Luna. Terra matches GPT‑5.5 performance at half the price, Luna delivers strong capability at lowest cost. Pricing per million tokens: Sol $5 input / $30 output; Terra $2.50 input / $15 output; Luna $1 input / $6 output. The series introduces more predictable prompt caching with explicit breakpoints and 30‑minute minimum cache life. Cache writes cost 1.25x original input, reads still get 90% discount. At US government request, OpenAI first offers to trusted partners before broader release.
Summary basis: official / RSS sourceUnless it says 'full article read', this summary is based only on publicly available content — it never pretends to have read restricted originals.
Sources
- Simon Willison：Blog
Hands-on notes on LLM tools, local models, and practical AI engineering.
- Simon Willison：Blog