Noometry

Model comparison

GPT-5.5 Instant vs Grok 4.3

Grok 4.3 is the stronger model overall, scoring 43.8 to 42.7 on the Noometry Index.

Last verified . 26 shared benchmarks.

GPT-5.5 Instant OpenAI

42.7

Rank #110 Confirmed

Grok 4.3 xAI

43.8

Rank #86 Confirmed

Summary

  • They share 26 benchmarks with published results for both. GPT-5.5 Instant scores higher in 6 categories and Grok 4.3 in 3 categories; 8 gaps are clear of the uncertainty.
  • The widest gap is in math, where Grok 4.3 leads 46.0 to 26.5.
  • The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 68.1% for GPT-5.5 Instant and 93.3% for Grok 4.3.

Side by side

GPT-5.5 InstantGrok 4.3
ProviderOpenAIxAI
Noometry Index42.743.8
Released2026-05-052026-04-17
WeightsProprietaryProprietary
Context window—1M
Max output—30K
Input $ / M tokens—$1.25
Output $ / M tokens—$2.50
Results tracked2740

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Category by category

Coding GPT-5.5 Instant leads

GPT-5.5 Instant: 44.3 (#74), Grok 4.3: 41.6 (#121)

BenchmarkGPT-5.5 InstantGrok 4.3
SciCode48.6%47.3%
LMArena Coding14331415
LMArena WebDev—1357
WeirdML—49.9%
ALE-Bench—944.17

Agentic & Tool Use Not comparable

GPT-5.5 Instant: —, Grok 4.3: 27.7 (#99)

BenchmarkGPT-5.5 InstantGrok 4.3
GDP.pdf—8%
LMArena Search—1165
Vending-Bench 2—35.26

Reasoning Grok 4.3 leads

GPT-5.5 Instant: 24.9 (#155), Grok 4.3: 35.9 (#68)

BenchmarkGPT-5.5 InstantGrok 4.3
CritPt0%8%
Chess Puzzles12%25%
LMArena Hard Prompts14261396
Epoch Capabilities Index142.52149.16
NYT Connections (extended)—55.2%
DTBench—90.7%
LMCA—38.3%
ForecastBench—60.3

Math Grok 4.3 leads

GPT-5.5 Instant: 26.5 (#259), Grok 4.3: 46.0 (#74)

BenchmarkGPT-5.5 InstantGrok 4.3
FrontierMath (Tiers 1-3)26.3%42.8%
FrontierMath Tier 42.4%14.6%
OTIS Mock AIME 2024-202568.1%93.3%
LMArena Math14201388
ProofBench—11%

Knowledge Grok 4.3 leads

GPT-5.5 Instant: 48.9 (#74), Grok 4.3: 52.5 (#62)

BenchmarkGPT-5.5 InstantGrok 4.3
GPQA Diamond82.5%88.8%
LMArena Expert14091385
SimpleQA Verified—33.2%

Multimodal GPT-5.5 Instant leads

GPT-5.5 Instant: 40.0 (#52), Grok 4.3: 31.6 (#104)

BenchmarkGPT-5.5 InstantGrok 4.3
LMArena Vision12501229
Blueprint-Bench 2—0%
LMArena Document1403—

Multilingual GPT-5.5 Instant leads

GPT-5.5 Instant: 52.8 (#80), Grok 4.3: 50.5 (#120)

BenchmarkGPT-5.5 InstantGrok 4.3
LMArena Non-English14171385
LMArena Chinese14561422
LMArena French14281412
LMArena German14111395
LMArena Japanese14081379
LMArena Korean13921356
LMArena Russian14311399
LMArena Spanish14291398

Instruction Following GPT-5.5 Instant leads

GPT-5.5 Instant: 74.2 (#100), Grok 4.3: 72.1 (#140)

BenchmarkGPT-5.5 InstantGrok 4.3
LMArena Instruction Following14061366

Long Context Too close to call

GPT-5.5 Instant: 43.4 (#96), Grok 4.3: 42.5 (#123)

BenchmarkGPT-5.5 InstantGrok 4.3
LMArena Longer Query14221393

Writing & Preference GPT-5.5 Instant leads

GPT-5.5 Instant: 61.8 (#85), Grok 4.3: 58.5 (#118)

BenchmarkGPT-5.5 InstantGrok 4.3
LMArena Text14191397
LMArena Creative Writing14191380
LMArena Multi-Turn14331406
EQ-Bench 4—1075

Frequently asked questions

Is GPT-5.5 Instant better than Grok 4.3?

Grok 4.3 is the stronger model overall, scoring 43.8 to 42.7 on the Noometry Index.

Is GPT-5.5 Instant or Grok 4.3 better for coding?

GPT-5.5 Instant scores higher on coding benchmarks: 44.3 versus 41.6 in the Noometry coding category.

How many benchmarks do GPT-5.5 Instant and Grok 4.3 share?

26 benchmarks have published results for both models. GPT-5.5 Instant has 27 scored results on Noometry and Grok 4.3 has 40.

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