OpenAI starts limited GPT-5.6 preview

OpenAI has begun a limited preview of GPT-5.6, introducing Sol, Terra, and Luna as three models aimed at different workloads. Sol is the flagship option for complex coding, research, biology, and cybersecurity tasks, while Terra targets general work at lower cost and Luna is designed for faster, higher-volume use.

The models are initially available through the OpenAI application programming interface and Codex to selected trusted partners, with broader access through ChatGPT, Codex, and the API planned in the coming weeks. API pricing starts at $1 per million input tokens and $6 per million output tokens for Luna; Terra costs $2.50 for input and $15 for output, and Sol is priced at $5 for input and $30 for output.

OpenAI reported Terminal-Bench 2.1 scores of 88.8 percent for GPT-5.6 Sol and 91.9 percent for Sol Ultra, but has not released its full evaluation package. The company says Sol is its most capable cybersecurity model to date, though it did not cross the Cyber Critical threshold under its Preparedness Framework.

Additional safeguards include model-level refusals, real-time classifiers for cyber and biology requests, account-level monitoring, differentiated access, and review of higher-risk outputs. OpenAI dedicated more than 700,000 A100-equivalent graphics processing unit hours to automated red-teaming, and GPT-5.6 Sol is scheduled to launch on Cerebras in July with speeds of up to 750 tokens per second.