Claude Opus 5 vs GPT-5.6 Sol
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
Claude Opus 5 and GPT-5.6 Sol score within 0.9 points of each other on the composite index, which is too close to call a winner on capability alone.
Their Arena Elo differs by only 10 points, inside the confidence intervals the public board reports, so human preference does not separate them.
Pick Claude Opus 5 when
- Stronger on MMLU-Pro: 95.7% against 95.1%.
Pick GPT-5.6 Sol when
- Cheaper input tokens — $4 against $5 per 1M, so Claude Opus 5 costs 1.3x as much to feed.
- Better value per point of measured capability: $0.042 per index point against $0.052.
Value per point of measured capability, at list input pricing: GPT-5.6 Sol $0.042 · Claude Opus 5 $0.052 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.
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