Claude Fable 5.1 vs Llama 4 (405B)
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
Claude Fable 5.1 leads on the composite index by 6.4 points (96.9 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 Claude Fable 5.1 when
- Higher composite index — 96.9 against 90.5, a gap of 6.4 points.
- Ahead on Arena Elo by 64 points (1504 vs 1440), which is outside the board's published confidence intervals.
- Stronger on MMLU-Pro: 95.9% 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.
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