Noometry

Model comparison

Claude Opus 5.5 vs Step 3

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 40.5 on the Noometry Index.

Last verified . 14 shared benchmarks.

Claude Opus 5.5 Anthropic

68.6

Rank #3 Confirmed

Step 3 StepFun

40.5

Rank #149 Confirmed

Summary

  • They share 14 benchmarks with published results for both. Claude Opus 5.5 scores higher in 9 categories and Step 3 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 37.6.
  • Step 3 has downloadable open weights; the other is API-only.

Side by side

Claude Opus 5.5Step 3
ProviderAnthropicStepFun
Noometry Index68.640.5
Released2026-09-22—
WeightsProprietaryOpen
Context window1M—
Max output128K—
Input $ / M tokens$4—
Output $ / M tokens$20—
Results tracked4417

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Category by category

Coding Claude Opus 5.5 leads

Claude Opus 5.5: 71.9 (#3), Step 3: 40.1 (#147)

BenchmarkClaude Opus 5.5Step 3
LMArena Coding15471367
FrontierCode54.6%—
CursorBench57.8%—
LMArena WebDev1813—
FrontierSWE62.3%—
SciCode66.9%—
MirrorCode77.4%—
ALE-Bench2,147—

Agentic & Tool Use Not comparable

Claude Opus 5.5: 45.3 (#15), Step 3: —

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

Reasoning Claude Opus 5.5 leads

Claude Opus 5.5: 80.2 (#3), Step 3: 28.4 (#105)

BenchmarkClaude Opus 5.5Step 3
LMArena Hard Prompts15351355
ARC-AGI-293.3%—
Kagi LLM Benchmark—62.3%
NYT Connections (extended)88.5%—
ARC-AGI-198.5%—
CritPt31.7%—
EBR-Bench71.4%—
Mystery Game Puzzles71%—
DTBench98.9%—
LMCA68.2%—
Epoch Capabilities Index167.33—

Math Claude Opus 5.5 leads

Claude Opus 5.5: 91.8 (#3), Step 3: 37.6 (#148)

BenchmarkClaude Opus 5.5Step 3
LMArena Math15061366
FrontierMath (Tiers 1-3)91.2%—
FrontierMath Tier 495%—
OTIS Mock AIME 2024-2025100%—
ProofBench100%—
FrontierMath Erdős2.9%—

Knowledge Claude Opus 5.5 leads

Claude Opus 5.5: 66.4 (#10), Step 3: 36.8 (#164)

BenchmarkClaude Opus 5.5Step 3
LMArena Expert15471333
GPQA Diamond90.6%—
SimpleQA Verified72.2%—

Multimodal Claude Opus 5.5 leads

Claude Opus 5.5: 57.8 (#1), Step 3: 35.5 (#86)

BenchmarkClaude Opus 5.5Step 3
LMArena Vision13211177
Blueprint-Bench 251.2%—
Furniture Assembly83.3%—

Multilingual Claude Opus 5.5 leads

Claude Opus 5.5: 59.1 (#2), Step 3: 46.3 (#159)

BenchmarkClaude Opus 5.5Step 3
LMArena Non-English15071327
LMArena Chinese15881397
LMArena Russian15201331
LMArena Spanish15071371
LMArena French1514—
LMArena German—1371
LMArena Korean—1269

Instruction Following Claude Opus 5.5 leads

Claude Opus 5.5: 80.0 (#3), Step 3: 70.4 (#164)

BenchmarkClaude Opus 5.5Step 3
LMArena Instruction Following15371332

Long Context Claude Opus 5.5 leads

Claude Opus 5.5: 47.1 (#19), Step 3: 40.3 (#157)

BenchmarkClaude Opus 5.5Step 3
LMArena Longer Query15321326

Writing & Preference Claude Opus 5.5 leads

Claude Opus 5.5: 78.2 (#3), Step 3: 54.3 (#151)

BenchmarkClaude Opus 5.5Step 3
LMArena Text15151350
LMArena Creative Writing15331321
LMArena Multi-Turn14991341
EQ-Bench Creative Writing2050—

Frequently asked questions

Is Claude Opus 5.5 better than Step 3?

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 40.5 on the Noometry Index.

Is Claude Opus 5.5 or Step 3 better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 40.1 in the Noometry coding category.

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

14 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and Step 3 has 17.

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