GPT-5.6 Luna vs Mistral Large 3
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
GPT-5.6 Luna leads on the composite index by 2.8 points (92 vs 89.2).
Cost is the sharper difference: Mistral Large 3 is 2.5x the input price of GPT-5.6 Luna ($0.5 against $0.2 per 1M), so at volume the choice is usually decided by budget rather than benchmarks.
Pick GPT-5.6 Luna when
- Higher composite index — 92 against 89.2, a gap of 2.8 points.
- Ahead on Arena Elo by 25 points (1455 vs 1430), which is outside the board's published confidence intervals.
- Stronger on MMLU-Pro: 92% against 89.2%.
- Cheaper input tokens — $0.2 against $0.5 per 1M, so Mistral Large 3 costs 2.5x as much to feed.
- Better value per point of measured capability: $0.002 per index point against $0.006.
Pick Mistral Large 3 when
On these measures Mistral Large 3 does not lead GPT-5.6 Luna anywhere, so pick it only for reasons outside this table — an existing integration, a region, or a contract.
Value per point of measured capability, at list input pricing: GPT-5.6 Luna $0.002 · Mistral Large 3 $0.006 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 2026-09-14. 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.
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