Noometry

Model comparison

Grok 4.3 vs Grok 4 Fast

Grok 4.3 is the stronger model overall, scoring 43.6 to 39.0 on the Noometry Index.

Last verified . 23 shared benchmarks.

Grok 4.3 xAI

43.6

Rank #80 Confirmed

Grok 4 Fast xAI

39.0

Rank #164 Confirmed

Summary

  • They share 23 benchmarks with published results for both. Grok 4.3 scores higher in 4 categories and Grok 4 Fast in 5 categories; 8 gaps are clear of the uncertainty.
  • The widest gap is in knowledge, where Grok 4.3 leads 52.5 to 31.5.
  • The biggest single-benchmark swing is DTBench: 90.7% for Grok 4.3 and 82.7% for Grok 4 Fast.

Side by side

Grok 4.3Grok 4 Fast
ProviderxAIxAI
Noometry Index43.639.0
Released2026-04-172025-09-19
WeightsProprietaryProprietary
Context window1M—
Max output30K—
Input $ / M tokens$1.25—
Output $ / M tokens$2.50—
Results tracked4030

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Category by category

Coding Grok 4.3 leads

Grok 4.3: 41.3 (#117), Grok 4 Fast: 32.3 (#264)

BenchmarkGrok 4.3Grok 4 Fast
LMArena WebDev13571160
WeirdML49.9%42.9%
LMArena Coding14151429
SciCode47.3%—
ALE-Bench944.17—

Agentic & Tool Use Grok 4 Fast leads

Grok 4.3: 27.6 (#93), Grok 4 Fast: 29.3 (#80)

BenchmarkGrok 4.3Grok 4 Fast
LMArena Search11651171
τ²-bench Banking—15.7%
Cybench—30%
GDP.pdf8%—
Vending-Bench 235.26—

Reasoning Grok 4.3 leads

Grok 4.3: 34.9 (#60), Grok 4 Fast: 22.5 (#179)

BenchmarkGrok 4.3Grok 4 Fast
LMArena Hard Prompts13971413
DTBench90.7%82.7%
Epoch Capabilities Index149.13144.21
ForecastBench60.360.5
ARC-AGI-2—5.3%
Kagi LLM Benchmark—66.1%
NYT Connections (extended)55.2%—
ARC-AGI-1—48.5%
CritPt8%—
Chess Puzzles25%—
LMCA38.3%—

Math Grok 4.3 leads

Grok 4.3: 45.8 (#60), Grok 4 Fast: 36.1 (#126)

BenchmarkGrok 4.3Grok 4 Fast
LMArena Math13881419
FrontierMath (Tiers 1-3)42.8%—
FrontierMath Tier 414.6%—
OTIS Mock AIME 2024-202593.3%—
ProofBench11%—

Knowledge Grok 4.3 leads

Grok 4.3: 52.5 (#57), Grok 4 Fast: 31.5 (#211)

BenchmarkGrok 4.3Grok 4 Fast
LMArena Expert13851411
GPQA Diamond88.8%—
SimpleQA Verified33.2%—
Vectara Hallucination Rate—19.7%

Multimodal Not comparable

Grok 4.3: 31.6 (#96), Grok 4 Fast: —

BenchmarkGrok 4.3Grok 4 Fast
LMArena Vision1231—
Blueprint-Bench 20%—

Multilingual Too close to call

Grok 4.3: 50.7 (#114), Grok 4 Fast: 51.5 (#106)

BenchmarkGrok 4.3Grok 4 Fast
LMArena Non-English13851397
LMArena Chinese14231458
LMArena French14121433
LMArena German13951383
LMArena Japanese13791358
LMArena Korean13571359
LMArena Russian13991387
LMArena Spanish14021414

Instruction Following Grok 4 Fast leads

Grok 4.3: 72.3 (#135), Grok 4 Fast: 73.4 (#116)

BenchmarkGrok 4.3Grok 4 Fast
LMArena Instruction Following13661388

Long Context Grok 4 Fast leads

Grok 4.3: 42.5 (#118), Grok 4 Fast: 63.2 (#3)

BenchmarkGrok 4.3Grok 4 Fast
LMArena Longer Query13931415
Fiction.LiveBench—94.4%

Writing & Preference Grok 4 Fast leads

Grok 4.3: 58.6 (#112), Grok 4 Fast: 60.2 (#96)

BenchmarkGrok 4.3Grok 4 Fast
LMArena Text13971407
LMArena Creative Writing13801388
LMArena Multi-Turn14061414
EQ-Bench 41075—

Frequently asked questions

Is Grok 4.3 better than Grok 4 Fast?

Grok 4.3 is the stronger model overall, scoring 43.6 to 39.0 on the Noometry Index.

Is Grok 4.3 or Grok 4 Fast better for coding?

Grok 4.3 scores higher on coding benchmarks: 41.3 versus 32.3 in the Noometry coding category.

How many benchmarks do Grok 4.3 and Grok 4 Fast share?

23 benchmarks have published results for both models. Grok 4.3 has 40 scored results on Noometry and Grok 4 Fast has 30.

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