GLM-5.2 vs Gemini 3.8 Flash
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
Gemini 3.8 Flash leads on the composite index by 2 points (91.5 vs 93.5).
Cost is the sharper difference: GLM-5.2 is 1.9x the input price of Gemini 3.8 Flash ($1.4 against $0.75 per 1M), so at volume the choice is usually decided by budget rather than benchmarks.
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
- Open weights, so it is the only one of the two you can run on your own hardware or keep data entirely in-house.
Pick Gemini 3.8 Flash when
- Higher composite index — 93.5 against 91.5, a gap of 2 points.
- Ahead on Arena Elo by 29 points (1494 vs 1465), which is outside the board's published confidence intervals.
- Stronger on MMLU-Pro: 93.2% against 91.2%.
- Cheaper input tokens — $0.75 against $1.4 per 1M, so GLM-5.2 costs 1.9x as much to feed.
- Better value per point of measured capability: $0.008 per index point against $0.015.
Value per point of measured capability, at list input pricing: Gemini 3.8 Flash $0.008 · GLM-5.2 $0.015 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.