Noometry

Model comparison

Claude Opus 5.5 vs Step 3.7 Flash

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 37.3 on the Noometry Index. Step 3.7 Flash costs 19× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.

Last verified . 4 shared benchmarks.

Claude Opus 5.5 Anthropic

68.6

Rank #3 Confirmed

Step 3.7 Flash StepFun

37.3

Rank #207 Reported

Summary

  • They share 4 benchmarks with published results for both. Claude Opus 5.5 scores higher in 3 categories and Step 3.7 Flash in 0 categories; 3 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Claude Opus 5.5 leads 80.2 to 21.6.
  • The biggest single-benchmark swing is NYT Connections (extended): 88.5% for Claude Opus 5.5 and 39.7% for Step 3.7 Flash.
  • Step 3.7 Flash is cheaper at $0.18 / $1.11 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
  • Claude Opus 5.5 accepts more context: 1M tokens versus 256K.
  • Step 3.7 Flash has downloadable open weights; the other is API-only.

Side by side

Claude Opus 5.5Step 3.7 Flash
ProviderAnthropicStepFun
Noometry Index68.637.3
Released2026-09-222026-05-29
WeightsProprietaryOpen
Context window1M256K
Max output128K256K
Input $ / M tokens$4$0.18
Output $ / M tokens$20$1.11
Results tracked445

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Category by category

Coding Claude Opus 5.5 leads

Claude Opus 5.5: 71.9 (#3), Step 3.7 Flash: 40.0 (#150)

BenchmarkClaude Opus 5.5Step 3.7 Flash
SciCode66.9%40%
ALE-Bench2,147694.12
FrontierCode54.6%—
CursorBench57.8%—
LMArena WebDev1813—
FrontierSWE62.3%—
LMArena Coding1547—
MirrorCode77.4%—

Agentic & Tool Use Not comparable

Claude Opus 5.5: 45.3 (#15), Step 3.7 Flash: —

BenchmarkClaude Opus 5.5Step 3.7 Flash
APEX-Agents73.5%—
GDP.pdf30.6%—
Vending-Bench 29,235—

Reasoning Claude Opus 5.5 leads

Claude Opus 5.5: 80.2 (#3), Step 3.7 Flash: 21.6 (#219)

BenchmarkClaude Opus 5.5Step 3.7 Flash
NYT Connections (extended)88.5%39.7%
CritPt31.7%2.3%
ARC-AGI-293.3%—
ARC-AGI-198.5%—
EBR-Bench71.4%—
LMArena Hard Prompts1535—
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 3.7 Flash: 42.9 (#82)

BenchmarkClaude Opus 5.5Step 3.7 Flash
FrontierMath (Tiers 1-3)91.2%—
FrontierMath Tier 495%—
MathArena Final-Answer Competitions—68.5%
OTIS Mock AIME 2024-2025100%—
ProofBench100%—
LMArena Math1506—
FrontierMath Erdős2.9%—

Knowledge Not comparable

Claude Opus 5.5: 66.4 (#10), Step 3.7 Flash: —

BenchmarkClaude Opus 5.5Step 3.7 Flash
GPQA Diamond90.6%—
SimpleQA Verified72.2%—
LMArena Expert1547—

Multimodal Not comparable

Claude Opus 5.5: 57.8 (#1), Step 3.7 Flash: —

BenchmarkClaude Opus 5.5Step 3.7 Flash
LMArena Vision1321—
Blueprint-Bench 251.2%—
Furniture Assembly83.3%—

Multilingual Not comparable

Claude Opus 5.5: 59.1 (#2), Step 3.7 Flash: —

BenchmarkClaude Opus 5.5Step 3.7 Flash
LMArena Non-English1507—
LMArena Chinese1588—
LMArena French1514—
LMArena Russian1520—
LMArena Spanish1507—

Instruction Following Not comparable

Claude Opus 5.5: 80.0 (#3), Step 3.7 Flash: —

BenchmarkClaude Opus 5.5Step 3.7 Flash
LMArena Instruction Following1537—

Long Context Not comparable

Claude Opus 5.5: 47.1 (#19), Step 3.7 Flash: —

BenchmarkClaude Opus 5.5Step 3.7 Flash
LMArena Longer Query1532—

Writing & Preference Not comparable

Claude Opus 5.5: 78.2 (#3), Step 3.7 Flash: —

BenchmarkClaude Opus 5.5Step 3.7 Flash
LMArena Text1515—
LMArena Creative Writing1533—
EQ-Bench Creative Writing2050—
LMArena Multi-Turn1499—

Frequently asked questions

Is Claude Opus 5.5 better than Step 3.7 Flash?

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 37.3 on the Noometry Index. Step 3.7 Flash costs 19× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.

Which is cheaper, Claude Opus 5.5 or Step 3.7 Flash?

Step 3.7 Flash is cheaper. It lists at $0.18 per million input tokens and $1.11 per million output tokens; Claude Opus 5.5 lists at $4 and $20.

Is Claude Opus 5.5 or Step 3.7 Flash better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 40.0 in the Noometry coding category.

Which has the bigger context window?

Claude Opus 5.5 does, with 1M tokens against 256K.

How many benchmarks do Claude Opus 5.5 and Step 3.7 Flash share?

4 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and Step 3.7 Flash has 5.

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