GPT-5.6 Luna vs Muse Spark 1.1
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
GPT-5.6 Luna and Muse Spark 1.1 score within 0.3 points of each other on the composite index, which is too close to call a winner on capability alone.
Cost is the sharper difference: Muse Spark 1.1 is 6.3x the input price of GPT-5.6 Luna ($1.25 against $0.2 per 1M), so at volume the choice is usually decided by budget rather than benchmarks.
Pick GPT-5.6 Luna when
- Stronger on MMLU-Pro: 92% against 91.9%.
- Cheaper input tokens — $0.2 against $1.25 per 1M, so Muse Spark 1.1 costs 6.3x as much to feed.
- Better value per point of measured capability: $0.002 per index point against $0.014.
Pick Muse Spark 1.1 when
- Ahead on Arena Elo by 37 points (1492 vs 1455), which is outside the board's published confidence intervals.
Value per point of measured capability, at list input pricing: GPT-5.6 Luna $0.002 · Muse Spark 1.1 $0.014 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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