Noometry

Model comparison

Claude Sonnet 5.5 vs Grok 4.3

Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 43.8 on the Noometry Index. Grok 4.3 costs 2.6× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.

Last verified . 25 shared benchmarks.

Claude Sonnet 5.5 Anthropic

61.9

Rank #10 Confirmed

Grok 4.3 xAI

43.8

Rank #86 Confirmed

Summary

  • They share 25 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 10 categories and Grok 4.3 in 0 categories; 10 gaps are clear of the uncertainty.
  • The widest gap is in math, where Claude Sonnet 5.5 leads 87.9 to 46.0.
  • The biggest single-benchmark swing is ProofBench: 100% for Claude Sonnet 5.5 and 11% for Grok 4.3.
  • Grok 4.3 is cheaper at $1.25 / $2.50 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.

Side by side

Claude Sonnet 5.5Grok 4.3
ProviderAnthropicxAI
Noometry Index61.943.8
Released2026-09-282026-04-17
WeightsProprietaryProprietary
Context window1M1M
Max output128K30K
Input $ / M tokens$2$1.25
Output $ / M tokens$10$2.50
Results tracked3240

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Category by category

Coding Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 67.3 (#6), Grok 4.3: 41.6 (#121)

BenchmarkClaude Sonnet 5.5Grok 4.3
LMArena WebDev17741357
SciCode61%47.3%
LMArena Coding15131415
ALE-Bench1,819944.17
FrontierCode52.1%—
CursorBench55.5%—
FrontierSWE61.9%—
WeirdML—49.9%

Agentic & Tool Use Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 45.0 (#16), Grok 4.3: 27.7 (#99)

BenchmarkClaude Sonnet 5.5Grok 4.3
APEX-Agents75.5%—
GDP.pdf—8%
LMArena Search—1165
Vending-Bench 2—35.26

Reasoning Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 54.0 (#28), Grok 4.3: 35.9 (#68)

BenchmarkClaude Sonnet 5.5Grok 4.3
NYT Connections (extended)80.5%55.2%
CritPt31.4%8%
LMArena Hard Prompts14951396
Epoch Capabilities Index165.03149.16
Chess Puzzles—25%
Mystery Game Puzzles65%—
DTBench—90.7%
LMCA—38.3%
ForecastBench—60.3

Math Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 87.9 (#6), Grok 4.3: 46.0 (#74)

BenchmarkClaude Sonnet 5.5Grok 4.3
FrontierMath (Tiers 1-3)88.8%42.8%
FrontierMath Tier 480.5%14.6%
OTIS Mock AIME 2024-2025100%93.3%
ProofBench100%11%
LMArena Math15101388
FrontierMath Erdős2.9%—

Knowledge Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 66.0 (#12), Grok 4.3: 52.5 (#62)

BenchmarkClaude Sonnet 5.5Grok 4.3
GPQA Diamond95.6%88.8%
SimpleQA Verified46.5%33.2%
LMArena Expert15401385

Multimodal Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 51.5 (#6), Grok 4.3: 31.6 (#104)

BenchmarkClaude Sonnet 5.5Grok 4.3
LMArena Vision12891229
Blueprint-Bench 2—0%
Furniture Assembly75%—

Multilingual Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 55.3 (#30), Grok 4.3: 50.5 (#120)

BenchmarkClaude Sonnet 5.5Grok 4.3
LMArena Non-English14521385
LMArena Chinese15221422
LMArena Russian14511399
LMArena French—1412
LMArena German—1395
LMArena Japanese—1379
LMArena Korean—1356
LMArena Spanish—1398

Instruction Following Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 78.3 (#11), Grok 4.3: 72.1 (#140)

BenchmarkClaude Sonnet 5.5Grok 4.3
LMArena Instruction Following14951366

Long Context Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 45.9 (#28), Grok 4.3: 42.5 (#123)

BenchmarkClaude Sonnet 5.5Grok 4.3
LMArena Longer Query14981393

Writing & Preference Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 66.0 (#40), Grok 4.3: 58.5 (#118)

BenchmarkClaude Sonnet 5.5Grok 4.3
LMArena Text14711397
LMArena Creative Writing14651380
LMArena Multi-Turn14741406
EQ-Bench 4—1075

Frequently asked questions

Is Claude Sonnet 5.5 better than Grok 4.3?

Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 43.8 on the Noometry Index. Grok 4.3 costs 2.6× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.

Which is cheaper, Claude Sonnet 5.5 or Grok 4.3?

Grok 4.3 is cheaper. It lists at $1.25 per million input tokens and $2.50 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.

Is Claude Sonnet 5.5 or Grok 4.3 better for coding?

Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 41.6 in the Noometry coding category.

Which has the bigger context window?

Both accept 1M tokens.

How many benchmarks do Claude Sonnet 5.5 and Grok 4.3 share?

25 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and Grok 4.3 has 40.

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