GPT-6 Astra vs Claude Opus 5
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
GPT-6 Astra and Claude Opus 5 score within 0.1 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 3 points, inside the confidence intervals the public board reports, so human preference does not separate them.
Cost is the sharper difference: GPT-6 Astra is 2x the input price of Claude Opus 5 ($10 against $5 per 1M), so at volume the choice is usually decided by budget rather than benchmarks.
Pick GPT-6 Astra when
- Stronger on MMLU-Pro: 95.8% against 95.7%.
Pick Claude Opus 5 when
- Cheaper input tokens — $5 against $10 per 1M, so GPT-6 Astra costs 2x as much to feed.
- Better value per point of measured capability: $0.052 per index point against $0.103.
Value per point of measured capability, at list input pricing: Claude Opus 5 $0.052 · GPT-6 Astra $0.103 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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