Noometry

Model comparison

GPT-5.5 Instant vs Grok 4.5

Grok 4.5 is the stronger model overall, scoring 55.0 to 42.7 on the Noometry Index.

Last verified . 27 shared benchmarks.

GPT-5.5 Instant OpenAI

42.7

Rank #110 Confirmed

Grok 4.5 xAI

55.0

Rank #25 Confirmed

Summary

  • They share 27 benchmarks with published results for both. GPT-5.5 Instant scores higher in 1 category and Grok 4.5 in 8 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in math, where Grok 4.5 leads 60.9 to 26.5.
  • The biggest single-benchmark swing is FrontierMath (Tiers 1-3): 26.3% for GPT-5.5 Instant and 57.2% for Grok 4.5.

Side by side

GPT-5.5 InstantGrok 4.5
ProviderOpenAIxAI
Noometry Index42.755.0
Released2026-05-052026-07-08
WeightsProprietaryProprietary
Context window—500K
Max output—500K
Input $ / M tokens—$2
Output $ / M tokens—$6
Results tracked2752

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Category by category

Coding Grok 4.5 leads

GPT-5.5 Instant: 44.3 (#74), Grok 4.5: 52.2 (#35)

BenchmarkGPT-5.5 InstantGrok 4.5
SciCode48.6%54.1%
LMArena Coding14331474
DeepSWE—53.8%
FrontierCode—42.4%
LMArena WebDev—1553
WeirdML—46.4%
ALE-Bench—1,309

Agentic & Tool Use Not comparable

GPT-5.5 Instant: —, Grok 4.5: 44.4 (#17)

BenchmarkGPT-5.5 InstantGrok 4.5
APEX-Agents—56.2%
τ²-bench Banking—47.9%
PostTrainBench—23.4%
GBAEval—65.4%
GDP.pdf—14%
LMArena Search—1213
Vending-Bench 2—3,887

Reasoning Grok 4.5 leads

GPT-5.5 Instant: 24.9 (#155), Grok 4.5: 56.1 (#25)

BenchmarkGPT-5.5 InstantGrok 4.5
CritPt0%15.4%
Chess Puzzles12%36%
LMArena Hard Prompts14261462
Epoch Capabilities Index142.52153.92
ARC-AGI-2—52.6%
SimpleBench—70%
Kagi LLM Benchmark—83.5%
NYT Connections (extended)—79.9%
ARC-AGI-1—87.2%
DTBench—96.5%
LMCA—45.2%
Surface Evolver Bench—74.4%

Math Grok 4.5 leads

GPT-5.5 Instant: 26.5 (#259), Grok 4.5: 60.9 (#35)

BenchmarkGPT-5.5 InstantGrok 4.5
FrontierMath (Tiers 1-3)26.3%57.2%
FrontierMath Tier 42.4%24.4%
OTIS Mock AIME 2024-202568.1%97.8%
LMArena Math14201459
ProofBench—31%

Knowledge Grok 4.5 leads

GPT-5.5 Instant: 48.9 (#74), Grok 4.5: 62.3 (#24)

BenchmarkGPT-5.5 InstantGrok 4.5
GPQA Diamond82.5%93.4%
LMArena Expert14091466
SimpleQA Verified—48.3%

Multimodal GPT-5.5 Instant leads

GPT-5.5 Instant: 40.0 (#52), Grok 4.5: 37.6 (#72)

BenchmarkGPT-5.5 InstantGrok 4.5
LMArena Vision12501288
LMArena Document14031452
Blueprint-Bench 2—27.3%
Furniture Assembly—22.5%

Multilingual Grok 4.5 leads

GPT-5.5 Instant: 52.8 (#80), Grok 4.5: 54.4 (#42)

BenchmarkGPT-5.5 InstantGrok 4.5
LMArena Non-English14171440
LMArena Chinese14561496
LMArena French14281456
LMArena German14111446
LMArena Japanese14081428
LMArena Korean13921404
LMArena Russian14311448
LMArena Spanish14291450

Instruction Following Grok 4.5 leads

GPT-5.5 Instant: 74.2 (#100), Grok 4.5: 76.0 (#48)

BenchmarkGPT-5.5 InstantGrok 4.5
LMArena Instruction Following14061446

Long Context Grok 4.5 leads

GPT-5.5 Instant: 43.4 (#96), Grok 4.5: 44.8 (#56)

BenchmarkGPT-5.5 InstantGrok 4.5
LMArena Longer Query14221463

Writing & Preference Grok 4.5 leads

GPT-5.5 Instant: 61.8 (#85), Grok 4.5: 65.8 (#42)

BenchmarkGPT-5.5 InstantGrok 4.5
LMArena Text14191448
LMArena Creative Writing14191442
LMArena Multi-Turn14331456
EQ-Bench Creative Writing—1579

Frequently asked questions

Is GPT-5.5 Instant better than Grok 4.5?

Grok 4.5 is the stronger model overall, scoring 55.0 to 42.7 on the Noometry Index.

Is GPT-5.5 Instant or Grok 4.5 better for coding?

Grok 4.5 scores higher on coding benchmarks: 52.2 versus 44.3 in the Noometry coding category.

How many benchmarks do GPT-5.5 Instant and Grok 4.5 share?

27 benchmarks have published results for both models. GPT-5.5 Instant has 27 scored results on Noometry and Grok 4.5 has 52.

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