Noometry

Model comparison

Claude Opus 4.1 vs Step 3.5 Flash

Step 3.5 Flash is the stronger model overall, scoring 42.3 to 41.0 on the Noometry Index.

Last verified . 17 shared benchmarks.

Claude Opus 4.1 Anthropic

41.0

Rank #142 Confirmed

Step 3.5 Flash StepFun

42.3

Rank #116 Confirmed

Summary

  • They share 17 benchmarks with published results for both. Claude Opus 4.1 scores higher in 7 categories and Step 3.5 Flash in 1 category; 8 gaps are clear of the uncertainty.
  • The widest gap is in math, where Step 3.5 Flash leads 42.6 to 22.3.
  • Step 3.5 Flash is cheaper at $0.10 / $0.30 per million input/output tokens, against $15 / $75 for Claude Opus 4.1.
  • Step 3.5 Flash accepts more context: 256K tokens versus 200K.
  • Step 3.5 Flash has downloadable open weights; the other is API-only.

Side by side

Claude Opus 4.1Step 3.5 Flash
ProviderAnthropicStepFun
Noometry Index41.042.3
Released2025-08-052026-01-29
WeightsProprietaryOpen
Context window200K256K
Max output32K256K
Input $ / M tokens$15$0.10
Output $ / M tokens$75$0.30
Results tracked4819

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Category by category

Coding Claude Opus 4.1 leads

Claude Opus 4.1: 44.4 (#73), Step 3.5 Flash: 42.4 (#105)

BenchmarkClaude Opus 4.1Step 3.5 Flash
LMArena Coding14791436
SWE-bench Verified73.3%—
LMArena WebDev1390—
WeirdML45.9%—
ALE-Bench674.77—
AlgoTune1.34—

Agentic & Tool Use Not comparable

Claude Opus 4.1: 35.0 (#41), Step 3.5 Flash: —

BenchmarkClaude Opus 4.1Step 3.5 Flash
Terminal-Bench38%—
GDPval43.6%—
Cybench42%—
DeepResearch Bench48.3%—
LMArena Search1148—
METR Time Horizons66.8%—

Reasoning Claude Opus 4.1 leads

Claude Opus 4.1: 32.2 (#76), Step 3.5 Flash: 22.2 (#202)

BenchmarkClaude Opus 4.1Step 3.5 Flash
LMArena Hard Prompts14431411
SimpleBench60%—
NYT Connections (extended)—28.4%
Chess Puzzles7%—
EnigmaEval7.2%—
EBR-Bench7.9%—
Mystery Game Puzzles21%—
DTBench80%—
LMCA37.1%—
Epoch Capabilities Index144.12—
ForecastBench62—

Math Step 3.5 Flash leads

Claude Opus 4.1: 22.3 (#277), Step 3.5 Flash: 42.6 (#84)

BenchmarkClaude Opus 4.1Step 3.5 Flash
LMArena Math14311408
FrontierMath (Tiers 1-3)12.6%—
FrontierMath Tier 42.4%—
MathArena Final-Answer Competitions—66.8%
OTIS Mock AIME 2024-202568.9%—
FrontierMath (Feb 2025 set)7.2%—
FrontierMath Tier 4 (v1)4.2%—

Knowledge Claude Opus 4.1 leads

Claude Opus 4.1: 42.0 (#101), Step 3.5 Flash: 39.6 (#132)

BenchmarkClaude Opus 4.1Step 3.5 Flash
LMArena Expert14391421
GPQA Diamond77.3%—
Humanity's Last Exam11.5%—
Confabulations17.1%—
Vectara Hallucination Rate11.8%—

Multimodal Not comparable

Claude Opus 4.1: 26.8 (#119), Step 3.5 Flash: —

BenchmarkClaude Opus 4.1Step 3.5 Flash
VPCT35%—

Multilingual Claude Opus 4.1 leads

Claude Opus 4.1: 52.0 (#95), Step 3.5 Flash: 50.5 (#119)

BenchmarkClaude Opus 4.1Step 3.5 Flash
LMArena Non-English14051385
LMArena Chinese14271447
LMArena French14311421
LMArena German14131405
LMArena Japanese13781354
LMArena Korean13801352
LMArena Russian14221385
LMArena Spanish14481419

Instruction Following Claude Opus 4.1 leads

Claude Opus 4.1: 75.6 (#58), Step 3.5 Flash: 73.1 (#124)

BenchmarkClaude Opus 4.1Step 3.5 Flash
LMArena Instruction Following14351385

Long Context Claude Opus 4.1 leads

Claude Opus 4.1: 44.5 (#63), Step 3.5 Flash: 42.8 (#117)

BenchmarkClaude Opus 4.1Step 3.5 Flash
LMArena Longer Query14551402

Writing & Preference Claude Opus 4.1 leads

Claude Opus 4.1: 62.4 (#74), Step 3.5 Flash: 58.8 (#113)

BenchmarkClaude Opus 4.1Step 3.5 Flash
LMArena Text14191403
LMArena Creative Writing14121357
LMArena Multi-Turn14441405
Short-Story Creative Writing84.7%—

Frequently asked questions

Is Claude Opus 4.1 better than Step 3.5 Flash?

Step 3.5 Flash is the stronger model overall, scoring 42.3 to 41.0 on the Noometry Index.

Which is cheaper, Claude Opus 4.1 or Step 3.5 Flash?

Step 3.5 Flash is cheaper. It lists at $0.10 per million input tokens and $0.30 per million output tokens; Claude Opus 4.1 lists at $15 and $75.

Is Claude Opus 4.1 or Step 3.5 Flash better for coding?

Claude Opus 4.1 scores higher on coding benchmarks: 44.4 versus 42.4 in the Noometry coding category.

Which has the bigger context window?

Step 3.5 Flash does, with 256K tokens against 200K.

How many benchmarks do Claude Opus 4.1 and Step 3.5 Flash share?

17 benchmarks have published results for both models. Claude Opus 4.1 has 48 scored results on Noometry and Step 3.5 Flash has 19.

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