GLM-5.2 vs Claude Sonnet 5
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
Claude Sonnet 5 leads on the composite index by 3.3 points (91.5 vs 94.8).
Their Arena Elo differs by only 7 points, inside the confidence intervals the public board reports, so human preference does not separate them.
Only GLM-5.2 ships open weights, which decides it outright if the workload has to run on your own hardware.
Pick GLM-5.2 when
- Cheaper input tokens — $1.4 against $2 per 1M, so Claude Sonnet 5 costs 1.4x as much to feed.
- Open weights, so it is the only one of the two you can run on your own hardware or keep data entirely in-house.
- Better value per point of measured capability: $0.015 per index point against $0.021.
Pick Claude Sonnet 5 when
- Higher composite index — 94.8 against 91.5, a gap of 3.3 points.
- Stronger on MMLU-Pro: 94.6% against 91.2%.
Value per point of measured capability, at list input pricing: GLM-5.2 $0.015 · Claude Sonnet 5 $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 2026-09-14. 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.
Our reporting on Z.ai and Anthropic
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