GLM-5.2 vs GPT-5.6 Terra
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
GPT-5.6 Terra leads on the composite index by 2.4 points (91.5 vs 93.9).
Their Arena Elo differs by only 5 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 GPT-5.6 Terra 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 GPT-5.6 Terra when
- Higher composite index — 93.9 against 91.5, a gap of 2.4 points.
- Stronger on MMLU-Pro: 93.5% against 91.2%.
Value per point of measured capability, at list input pricing: GLM-5.2 $0.015 · GPT-5.6 Terra $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.
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