GPT-5.6 Luna vs Grok 4.6
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
Grok 4.6 leads on the composite index by 1.8 points (92 vs 93.8).
Cost is the sharper difference: Grok 4.6 is 10x the input price of GPT-5.6 Luna ($2 against $0.2 per 1M), so at volume the choice is usually decided by budget rather than benchmarks.
Pick GPT-5.6 Luna when
- Cheaper input tokens — $0.2 against $2 per 1M, so Grok 4.6 costs 10x as much to feed.
- Better value per point of measured capability: $0.002 per index point against $0.021.
Pick Grok 4.6 when
- Higher composite index — 93.8 against 92, a gap of 1.8 points.
- Ahead on Arena Elo by 15 points (1470 vs 1455), which is outside the board's published confidence intervals.
- Stronger on MMLU-Pro: 93.1% against 92%.
Value per point of measured capability, at list input pricing: GPT-5.6 Luna $0.002 · Grok 4.6 $0.021 per index point. Run your own token mix through the token cost calculator — a comparison at list price ignores caching and batch discounts, which move real bills more than this gap does.
Where these numbers come from
Figures as of 2026-09-07. Arena Elo and pricing are read from the public board and each vendor's own pricing page; see the full leaderboard for all 34 models and which columns are measured rather than estimated, or the benchmark matrix for scores benchmark by benchmark.