DeepSeek-V4 Pro vs Llama 4 (405B)
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
DeepSeek-V4 Pro
DeepSeek
AI Mastery Index91.8
LMSYS Arena1449
Technical (MMLU-Pro)91.8%
Cost per 1M Tokens$0.435
Llama 4 (405B)
Meta
AI Mastery Index90.5
LMSYS Arena1440
Technical (MMLU-Pro)90.5%
Cost per 1M Tokens$0
Which should you use?
DeepSeek-V4 Pro leads on the composite index by 1.3 points (91.8 vs 90.5).
Their Arena Elo differs by only 9 points, inside the confidence intervals the public board reports, so human preference does not separate them.
Only Llama 4 (405B) ships open weights, which decides it outright if the workload has to run on your own hardware.
Pick DeepSeek-V4 Pro when
- Higher composite index — 91.8 against 90.5, a gap of 1.3 points.
- Stronger on MMLU-Pro: 91.8% 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 2026-09-14. 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.