GPT-5.3 Codex (xhigh) vs GPT-5.6 Luna (high)

OpenAI · OpenAI · catalog 2026-09-14

Trade-off: GPT-5.6 Luna (high) is cheaper ($0.174 vs $1.869/M); GPT-5.3 Codex (xhigh) scores higher on intelligence (32.5 vs 32.4).
GPT-5.3 Codex (xhigh)GPT-5.6 Luna (high)
Speed (tok/s)127.2 measured101.2 measured
Blended $/M$1.869 derived$0.174 derived
Intelligence index32.5 measured32.4 measured
TTFT (ms)505 measured738 measured
Context400k list—
Coding indexnot measured for both
Agentic indexnot measured for both

GPT-5.3 Codex (xhigh) card · GPT-5.6 Luna (high) 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.