Noometry

Model comparison

Claude Opus 5.5 vs Grok 3

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 39.9 on the Noometry Index.

Last verified . 20 shared benchmarks.

Claude Opus 5.5 Anthropic

68.6

Rank #3 Confirmed

Grok 3 xAI

39.9

Rank #157 Confirmed

Summary

  • They share 20 benchmarks with published results for both. Claude Opus 5.5 scores higher in 9 categories and Grok 3 in 0 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Claude Opus 5.5 leads 80.2 to 13.7.
  • The biggest single-benchmark swing is ARC-AGI-2: 93.3% for Claude Opus 5.5 and 0% for Grok 3.

Side by side

Claude Opus 5.5Grok 3
ProviderAnthropicxAI
Noometry Index68.639.9
Released2026-09-222025-04-09
WeightsProprietaryProprietary
Context window1M—
Max output128K—
Input $ / M tokens$4—
Output $ / M tokens$20—
Results tracked4440

Sponsored placements are available on pages like this one. Advertise on Noometry

Category by category

Coding Claude Opus 5.5 leads

Claude Opus 5.5: 71.9 (#3), Grok 3: 41.9 (#115)

BenchmarkClaude Opus 5.5Grok 3
LMArena Coding15471432
FrontierCode54.6%—
Aider Polyglot—53.3%
CursorBench57.8%—
LMArena WebDev1813—
FrontierSWE62.3%—
SciCode66.9%—
WeirdML—37.2%
MirrorCode77.4%—
ALE-Bench2,147—

Agentic & Tool Use Claude Opus 5.5 leads

Claude Opus 5.5: 45.3 (#15), Grok 3: 30.5 (#76)

BenchmarkClaude Opus 5.5Grok 3
APEX-Agents73.5%—
BALROG—29.5%
GDP.pdf30.6%—
Vending-Bench 29,235—

Reasoning Claude Opus 5.5 leads

Claude Opus 5.5: 80.2 (#3), Grok 3: 13.7 (#333)

BenchmarkClaude Opus 5.5Grok 3
ARC-AGI-293.3%0%
ARC-AGI-198.5%5.5%
LMArena Hard Prompts15351434
Epoch Capabilities Index167.33138.33
SimpleBench—36.1%
Kagi LLM Benchmark—61.3%
NYT Connections (extended)88.5%—
CritPt31.7%—
EBR-Bench71.4%—
Mystery Game Puzzles71%—
DTBench98.9%—
LMCA68.2%—

Math Claude Opus 5.5 leads

Claude Opus 5.5: 91.8 (#3), Grok 3: 38.0 (#145)

BenchmarkClaude Opus 5.5Grok 3
OTIS Mock AIME 2024-2025100%55.6%
LMArena Math15061391
FrontierMath (Tiers 1-3)91.2%—
FrontierMath Tier 495%—
ProofBench100%—
Omni-MATH—46.4%
MATH Level 5—88.7%
FrontierMath (Feb 2025 set)—3.8%
FrontierMath Erdős2.9%—
FrontierMath Tier 4 (v1)—0%

Knowledge Claude Opus 5.5 leads

Claude Opus 5.5: 66.4 (#10), Grok 3: 46.2 (#82)

BenchmarkClaude Opus 5.5Grok 3
GPQA Diamond90.6%75.8%
LMArena Expert15471421
SimpleQA Verified72.2%—
MMLU-Pro—78.8%
Confabulations—14.2%
Vectara Hallucination Rate—5.8%
GPQA (HELM)—65%

Multimodal Not comparable

Claude Opus 5.5: 57.8 (#1), Grok 3: —

BenchmarkClaude Opus 5.5Grok 3
LMArena Vision1321—
Blueprint-Bench 251.2%—
Furniture Assembly83.3%—

Multilingual Claude Opus 5.5 leads

Claude Opus 5.5: 59.1 (#2), Grok 3: 52.3 (#87)

BenchmarkClaude Opus 5.5Grok 3
LMArena Non-English15071410
LMArena Chinese15881448
LMArena French15141460
LMArena Russian15201416
LMArena Spanish15071417
LMArena German—1431
LMArena Japanese—1387
LMArena Korean—1373

Instruction Following Claude Opus 5.5 leads

Claude Opus 5.5: 80.0 (#3), Grok 3: 75.0 (#73)

BenchmarkClaude Opus 5.5Grok 3
LMArena Instruction Following15371409
IFEval—88.4%

Long Context Claude Opus 5.5 leads

Claude Opus 5.5: 47.1 (#19), Grok 3: 38.7 (#192)

BenchmarkClaude Opus 5.5Grok 3
LMArena Longer Query15321439
Fiction.LiveBench—58.3%

Writing & Preference Claude Opus 5.5 leads

Claude Opus 5.5: 78.2 (#3), Grok 3: 55.8 (#141)

BenchmarkClaude Opus 5.5Grok 3
LMArena Text15151426
LMArena Creative Writing15331414
EQ-Bench Creative Writing20501186
LMArena Multi-Turn14991425
Short-Story Creative Writing—76.4%
WildBench—84.9%

Frequently asked questions

Is Claude Opus 5.5 better than Grok 3?

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 39.9 on the Noometry Index.

Is Claude Opus 5.5 or Grok 3 better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 41.9 in the Noometry coding category.

How many benchmarks do Claude Opus 5.5 and Grok 3 share?

20 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and Grok 3 has 40.

Related comparisons

Go deeper