OpenAI has released the GPT-5.6 family — anchored by flagship Sol, balanced Terra, and cost-efficient Luna — clearing general availability after a weeks-long review by US government cybersecurity agencies. The July 2026 launch delivers OpenAI’s most capable and most efficient models to date, spanning ChatGPT, Codex, and the API.
The Family
The three tiers target different workloads rather than a single upgrade path:
- Sol — the flagship, built for the hardest reasoning, coding, and research tasks
- Terra — a balanced everyday model competitive with the previous generation at far lower cost
- Luna — the fastest and cheapest tier for high-volume inference
Benchmarks
GPT-5.6 Sol posts new state-of-the-art results across the board. On Agents’ Last Exam, it scores 53.6, eclipsing Claude Fable 5 by 13.1 points — even at medium reasoning it beats Fable 5 by 11.4 points at roughly a quarter of the estimated cost. On the Artificial Analysis Coding Agent Index it hits 80, and on cybersecurity evals such as ExploitBench it reaches 73.5 percent versus 47.9 percent for GPT-5.5. Terra and Luna outperform Fable 5 at about one-sixteenth the cost.
Pricing
The family is priced aggressively per 1 million tokens:
- Sol: $5 input / $30 output
- Terra: $2.50 input / $15 output
- Luna: $1 input / $6 output
Programmatic tool calling and predictable prompt caching, with a 30-minute minimum cache life and a 90 percent cached-input discount, cut effective enterprise costs further.
The Government Review
General availability follows a security assessment by US government cyber agencies — a step that has become standard for frontier releases since the US adopted formal review of the most capable systems. OpenAI says GPT-5.6 ships with its most robust safeguards yet, calibrated by capability, with verified defensive users able to access more through its Trusted Access programs.
What This Means
On benchmarks, price, and safety process, GPT-5.6 resets the frontier: historically strong results at fraction-of-competitor costs, wrapped in the security review the market now expects. The Sol/Terra/Luna split gives OpenAI durable upgrade paths — the number churns, but customers pick a tier and ride it forward.