Gemini 3.8 Flash vs Grok 4.6
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
Gemini 3.8 Flash and Grok 4.6 score within 0.3 points of each other on the composite index, which is too close to call a winner on capability alone.
Cost is the sharper difference: Grok 4.6 is 2.7x the input price of Gemini 3.8 Flash ($2 against $0.75 per 1M), so at volume the choice is usually decided by budget rather than benchmarks.
Pick Gemini 3.8 Flash when
- Ahead on Arena Elo by 24 points (1494 vs 1470), which is outside the board's published confidence intervals.
- Stronger on MMLU-Pro: 93.2% against 93.1%.
- Cheaper input tokens — $0.75 against $2 per 1M, so Grok 4.6 costs 2.7x as much to feed.
- Better value per point of measured capability: $0.008 per index point against $0.021.
Pick Grok 4.6 when
On these measures Grok 4.6 does not lead Gemini 3.8 Flash anywhere, so pick it only for reasons outside this table — an existing integration, a region, or a contract.
Value per point of measured capability, at list input pricing: Gemini 3.8 Flash $0.008 · Grok 4.6 $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 2026-09-07. 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.