GPT-5.6 Terra
FrontierClosed weightsTextReasoning
GPT-5.6 family model by OpenAI.
About the GPT-5.6 family
OpenAI's 2026 flagship generation, split into three tiers: Terra (largest/most capable), Sol (balanced mid-tier) and Luna (fast/light). Each runs at selectable reasoning effort from non-reasoning up to max.
All GPT-5.6 modelsHow this one is configured
This configuration runs in reasoning mode (thinks step-by-step before answering).
Also runs at: low · medium · high · xhigh · max effort
Effort controls how long the model thinks before answering — higher effort usually means better answers on hard problems, at the cost of speed and money. Same model underneath, so they share this page.