Noometry

Model comparison

Claude Opus 5.5 vs Llama 3.1-405B

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 30.7 on the Noometry Index.

Last verified . 19 shared benchmarks.

Claude Opus 5.5 Anthropic

68.6

Rank #3 Confirmed

Llama 3.1-405B Meta

30.7

Rank #288 Confirmed

Summary

  • They share 19 benchmarks with published results for both. Claude Opus 5.5 scores higher in 9 categories and Llama 3.1-405B in 0 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in math, where Claude Opus 5.5 leads 91.8 to 18.4.
  • The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 100% for Claude Opus 5.5 and 9.7% for Llama 3.1-405B.
  • Llama 3.1-405B has downloadable open weights; the other is API-only.

Side by side

Claude Opus 5.5Llama 3.1-405B
ProviderAnthropicMeta
Noometry Index68.630.7
Released2026-09-222024-07-23
WeightsProprietaryOpen
Context window1M—
Max output128K—
Input $ / M tokens$4—
Output $ / M tokens$20—
Results tracked4442

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Category by category

Coding Claude Opus 5.5 leads

Claude Opus 5.5: 71.9 (#3), Llama 3.1-405B: 33.1 (#262)

BenchmarkClaude Opus 5.5Llama 3.1-405B
LMArena Coding15471291
FrontierCode54.6%—
CursorBench57.8%—
LMArena WebDev1813—
FrontierSWE62.3%—
SciCode66.9%—
WeirdML—21.4%
MirrorCode77.4%—
ALE-Bench2,147—

Agentic & Tool Use Claude Opus 5.5 leads

Claude Opus 5.5: 45.3 (#15), Llama 3.1-405B: 21.0 (#140)

BenchmarkClaude Opus 5.5Llama 3.1-405B
APEX-Agents73.5%—
TheAgentCompany—7.4%
Cybench—7.5%
GDP.pdf30.6%—
Vending-Bench 29,235—

Reasoning Claude Opus 5.5 leads

Claude Opus 5.5: 80.2 (#3), Llama 3.1-405B: 16.8 (#300)

BenchmarkClaude Opus 5.5Llama 3.1-405B
LMArena Hard Prompts15351269
DTBench98.9%61.4%
Epoch Capabilities Index167.33128.75
ARC-AGI-293.3%—
SimpleBench—23%
Kagi LLM Benchmark—45%
NYT Connections (extended)88.5%—
ARC-AGI-198.5%—
CritPt31.7%—
EBR-Bench71.4%—
Mystery Game Puzzles71%—
LMCA68.2%—
BIG-Bench Hard—82.9%
ForecastBench—59.9
HellaSwag—89.2%
PIQA—85.9%
WinoGrande—89.2%

Math Claude Opus 5.5 leads

Claude Opus 5.5: 91.8 (#3), Llama 3.1-405B: 18.4 (#290)

BenchmarkClaude Opus 5.5Llama 3.1-405B
OTIS Mock AIME 2024-2025100%9.7%
LMArena Math15061281
FrontierMath (Tiers 1-3)91.2%—
FrontierMath Tier 495%—
ProofBench100%—
Omni-MATH—24.9%
MATH Level 5—49.8%
FrontierMath Erdős2.9%—

Knowledge Claude Opus 5.5 leads

Claude Opus 5.5: 66.4 (#10), Llama 3.1-405B: 30.4 (#227)

BenchmarkClaude Opus 5.5Llama 3.1-405B
GPQA Diamond90.6%50.9%
LMArena Expert15471243
SimpleQA Verified72.2%—
MMLU-Pro—72.3%
Confabulations—17.6%
GPQA (HELM)—52.2%
ARC (AI2) Challenge—95.3%
MMLU—84.5%
TriviaQA—82.7%

Multimodal Not comparable

Claude Opus 5.5: 57.8 (#1), Llama 3.1-405B: —

BenchmarkClaude Opus 5.5Llama 3.1-405B
LMArena Vision1321—
Blueprint-Bench 251.2%—
Furniture Assembly83.3%—

Multilingual Claude Opus 5.5 leads

Claude Opus 5.5: 59.1 (#2), Llama 3.1-405B: 40.7 (#214)

BenchmarkClaude Opus 5.5Llama 3.1-405B
LMArena Non-English15071248
LMArena Chinese15881242
LMArena French15141279
LMArena Russian15201265
LMArena Spanish15071260
LMArena German—1252
LMArena Japanese—1208
LMArena Korean—1184

Instruction Following Claude Opus 5.5 leads

Claude Opus 5.5: 80.0 (#3), Llama 3.1-405B: 65.9 (#214)

BenchmarkClaude Opus 5.5Llama 3.1-405B
LMArena Instruction Following15371259
IFEval—81.1%

Long Context Claude Opus 5.5 leads

Claude Opus 5.5: 47.1 (#19), Llama 3.1-405B: 38.4 (#197)

BenchmarkClaude Opus 5.5Llama 3.1-405B
LMArena Longer Query15321266

Writing & Preference Claude Opus 5.5 leads

Claude Opus 5.5: 78.2 (#3), Llama 3.1-405B: 38.9 (#251)

BenchmarkClaude Opus 5.5Llama 3.1-405B
LMArena Text15151284
LMArena Creative Writing15331262
EQ-Bench Creative Writing2050870
LMArena Multi-Turn14991297
WildBench—78.3%

Frequently asked questions

Is Claude Opus 5.5 better than Llama 3.1-405B?

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 30.7 on the Noometry Index.

Is Claude Opus 5.5 or Llama 3.1-405B better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 33.1 in the Noometry coding category.

How many benchmarks do Claude Opus 5.5 and Llama 3.1-405B share?

19 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and Llama 3.1-405B has 42.

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