Gemini 3.8 Flash vs Llama 4 (405B)
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Gemini 3.8 Flash
Google
AI Mastery Index93.5
LMSYS Arena1494
Technical (MMLU-Pro)93.2%
Cost per 1M Tokens$0.75
Llama 4 (405B)
Meta
AI Mastery Index90.5
LMSYS Arena1440
Technical (MMLU-Pro)90.5%
Cost per 1M Tokens$0
Which should you use?
Gemini 3.8 Flash leads on the composite index by 3 points (93.5 vs 90.5).
Only Llama 4 (405B) ships open weights, which decides it outright if the workload has to run on your own hardware.
Pick Gemini 3.8 Flash when
- Higher composite index — 93.5 against 90.5, a gap of 3 points.
- Ahead on Arena Elo by 54 points (1494 vs 1440), which is outside the board's published confidence intervals.
- Stronger on MMLU-Pro: 93.2% against 90.5%.
Pick Llama 4 (405B) 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.
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.