Quoting OpenAI
Simon Willison · Simon Willison · 2026-06-26
OpenAI announces a limited, U.S. government-coordinated preview of the GPT-5.6 model series — flagship Sol, balanced Terra, and affordable Luna — with new explicit prompt-caching features and pricing ranging from $1/$6 to $5/$30 per million input/output tokens.
Appears in
Extraction
Topics: llm-releasellm-pricingprompt-cachingopenaigovernment-ai-policy
Claims
- OpenAI is releasing three GPT-5.6 models: Sol (flagship, $5/$30 per million tokens), Terra (balanced, 2x cheaper than GPT-5.5, at $2.50/$15), and Luna (lowest cost, at $1/$6).
- At the U.S. government's request, GPT-5.6 is launching first as a limited preview to a vetted set of trusted partners before general availability.
- GPT-5.6 introduces explicit cache breakpoints and a 30-minute minimum cache lifetime, with cache writes billed at 1.25x the uncached input rate and reads receiving a 90% discount.
- Terra offers competitive performance to GPT-5.5 at half the price, positioning it as a cost-efficiency upgrade for existing customers.
Key quotes
We believe in broad access, and we plan to make GPT‑5.6 Sol, Terra, and Luna generally available in the coming weeks.
At their request, we are starting with a limited preview for a small group of trusted partners whose participation has been shared with the government, before releasing more broadly.
GPT‑5.6 also introduces more predictable prompt caching, including support for explicit cache breakpoints and a 30-minute minimum cache life. For GPT‑5.6 and later models, cache writes are billed at 1.25x the model's uncached input rate, while cache reads continue to receive the 90% cached-input discount.