Noometry

Model comparison

Claude Opus 5.5 vs Claude Sonnet 4.5

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 44.1 on the Noometry Index.

Last verified . 34 shared benchmarks.

Claude Opus 5.5 Anthropic

68.6

Rank #3 Confirmed

Claude Sonnet 4.5 Anthropic

44.1

Rank #81 Confirmed

Summary

  • They share 34 benchmarks with published results for both. Claude Opus 5.5 scores higher in 10 categories and Claude Sonnet 4.5 in 0 categories; 10 gaps are clear of the uncertainty.
  • The widest gap is in math, where Claude Opus 5.5 leads 91.8 to 32.3.
  • The biggest single-benchmark swing is FrontierMath Tier 4: 95% for Claude Opus 5.5 and 2.4% for Claude Sonnet 4.5.
  • Claude Sonnet 4.5 is cheaper at $3 / $15 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
  • Claude Opus 5.5 accepts more context: 1M tokens versus 200K.

Side by side

Claude Opus 5.5Claude Sonnet 4.5
ProviderAnthropicAnthropic
Noometry Index68.644.1
Released2026-09-222025-09-29
WeightsProprietaryProprietary
Context window1M200K
Max output128K64K
Input $ / M tokens$4$3
Output $ / M tokens$20$15
Results tracked4473

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Category by category

Coding Claude Opus 5.5 leads

Claude Opus 5.5: 71.9 (#3), Claude Sonnet 4.5: 47.3 (#61)

BenchmarkClaude Opus 5.5Claude Sonnet 4.5
LMArena WebDev18131393
SciCode66.9%44.7%
LMArena Coding15471489
ALE-Bench2,147796.15
SWE-bench Verified—71.3%
FrontierCode54.6%—
SWE-bench Verified (bash only)—71.4%
CursorBench57.8%—
SWE-bench Multilingual—67%
FrontierSWE62.3%—
GSO—14.7%
WeirdML—47.7%
MirrorCode77.4%—
AlgoTune—1.52

Agentic & Tool Use Claude Opus 5.5 leads

Claude Opus 5.5: 45.3 (#15), Claude Sonnet 4.5: 38.3 (#32)

BenchmarkClaude Opus 5.5Claude Sonnet 4.5
Vending-Bench 29,2353,839
Terminal-Bench—46.5%
APEX-Agents73.5%—
Berkeley Function Calling Leaderboard—73.2%
GDPval—42.5%
Remote Labor Index—2.1%
τ²-bench Airline—72%
τ²-bench Banking—25.3%
τ²-bench Retail—72.4%
τ²-bench Telecom—84.9%
Cybench—60%
DeepResearch Bench—52.6%
OSWorld—62.9%
GDP.pdf30.6%—
LMArena Search—1159
METR Time Horizons—67.4%

Reasoning Claude Opus 5.5 leads

Claude Opus 5.5: 80.2 (#3), Claude Sonnet 4.5: 26.9 (#125)

BenchmarkClaude Opus 5.5Claude Sonnet 4.5
ARC-AGI-293.3%13.6%
NYT Connections (extended)88.5%37.3%
ARC-AGI-198.5%63.7%
CritPt31.7%1.1%
EBR-Bench71.4%2.4%
LMArena Hard Prompts15351462
Mystery Game Puzzles71%17%
DTBench98.9%83.2%
LMCA68.2%38.8%
Epoch Capabilities Index167.33146.84
SimpleBench—54.3%
Kagi LLM Benchmark—57.9%
Chess Puzzles—12%
EnigmaEval—6%
ForecastBench—61.9

Math Claude Opus 5.5 leads

Claude Opus 5.5: 91.8 (#3), Claude Sonnet 4.5: 32.3 (#216)

BenchmarkClaude Opus 5.5Claude Sonnet 4.5
FrontierMath (Tiers 1-3)91.2%23.9%
FrontierMath Tier 495%2.4%
OTIS Mock AIME 2024-2025100%77.8%
ProofBench100%19%
LMArena Math15061449
Omni-MATH—55.3%
MATH Level 5—97.7%
FrontierMath (Feb 2025 set)—15.2%
FrontierMath Erdős2.9%—
FrontierMath Tier 4 (v1)—4.2%

Knowledge Claude Opus 5.5 leads

Claude Opus 5.5: 66.4 (#10), Claude Sonnet 4.5: 48.4 (#76)

BenchmarkClaude Opus 5.5Claude Sonnet 4.5
GPQA Diamond90.6%82.3%
SimpleQA Verified72.2%30.7%
LMArena Expert15471482
Humanity's Last Exam—13.7%
MMLU-Pro—86.9%
Vectara Hallucination Rate—12%
GPQA (HELM)—68.6%

Multimodal Claude Opus 5.5 leads

Claude Opus 5.5: 57.8 (#1), Claude Sonnet 4.5: 34.8 (#89)

BenchmarkClaude Opus 5.5Claude Sonnet 4.5
LMArena Vision1321—
VPCT—39.8%
Blueprint-Bench 251.2%—
Furniture Assembly83.3%—
LMArena Document—1450

Multilingual Claude Opus 5.5 leads

Claude Opus 5.5: 59.1 (#2), Claude Sonnet 4.5: 53.4 (#69)

BenchmarkClaude Opus 5.5Claude Sonnet 4.5
LMArena Non-English15071425
LMArena Chinese15881459
LMArena French15141458
LMArena Russian15201437
LMArena Spanish15071457
LMArena German—1427
LMArena Japanese—1390
LMArena Korean—1403

Instruction Following Claude Opus 5.5 leads

Claude Opus 5.5: 80.0 (#3), Claude Sonnet 4.5: 75.0 (#78)

BenchmarkClaude Opus 5.5Claude Sonnet 4.5
LMArena Instruction Following15371459
IFEval—85%

Long Context Claude Opus 5.5 leads

Claude Opus 5.5: 47.1 (#19), Claude Sonnet 4.5: 45.2 (#46)

BenchmarkClaude Opus 5.5Claude Sonnet 4.5
LMArena Longer Query15321476

Writing & Preference Claude Opus 5.5 leads

Claude Opus 5.5: 78.2 (#3), Claude Sonnet 4.5: 66.5 (#34)

BenchmarkClaude Opus 5.5Claude Sonnet 4.5
LMArena Text15151439
LMArena Creative Writing15331442
EQ-Bench Creative Writing20501678
LMArena Multi-Turn14991465
WildBench—85.4%

Frequently asked questions

Is Claude Opus 5.5 better than Claude Sonnet 4.5?

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 44.1 on the Noometry Index.

Which is cheaper, Claude Opus 5.5 or Claude Sonnet 4.5?

Claude Sonnet 4.5 is cheaper. It lists at $3 per million input tokens and $15 per million output tokens; Claude Opus 5.5 lists at $4 and $20.

Is Claude Opus 5.5 or Claude Sonnet 4.5 better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 47.3 in the Noometry coding category.

Which has the bigger context window?

Claude Opus 5.5 does, with 1M tokens against 200K.

How many benchmarks do Claude Opus 5.5 and Claude Sonnet 4.5 share?

34 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and Claude Sonnet 4.5 has 73.

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