GPT-5.5 (high) vs GPT-5.6 Terra (xhigh)

OpenAI · OpenAI · catalog 2026-09-14

GPT-5.6 Terra (xhigh) beats GPT-5.5 (high): cheaper ($1.74 vs $4.35/M) and at least as smart (index 38.2 vs 37.3).
GPT-5.5 (high)GPT-5.6 Terra (xhigh)
Speed (tok/s)80.5 measured82.6 measured
Blended $/M$4.35 derived$1.74 derived
Intelligence index37.3 measured38.2 measured
TTFT (ms)1037 measured2343 measured
Context——
Coding index72 measured71 measured
Agentic index35 measured42 measured

GPT-5.5 (high) card · GPT-5.6 Terra (xhigh) card · 3D observatory

Verdicts use price×intelligence dominance only, and only where both sides are measured; null cells stay null with their provenance (em-dash = not in catalog). Percentile-free by design — this page compares two models, not the field. Generated page — do not hand-edit.