Noometry

Model comparison

GPT-5.3 Chat vs Grok 4.5

Grok 4.5 is the stronger model overall, scoring 55.0 to 42.1 on the Noometry Index.

Last verified . 18 shared benchmarks.

GPT-5.3 Chat OpenAI

42.1

Rank #109 Confirmed

Grok 4.5 xAI

55.0

Rank #22 Confirmed

Summary

  • They share 18 benchmarks with published results for both. GPT-5.3 Chat scores higher in 0 categories and Grok 4.5 in 8 categories; 8 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Grok 4.5 leads 56.0 to 27.3.
  • Grok 4.5 is cheaper at $2 / $6 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.
  • Grok 4.5 accepts more context: 500K tokens versus 128K.

Side by side

GPT-5.3 ChatGrok 4.5
ProviderOpenAIxAI
Noometry Index42.155.0
Released2026-03-032026-07-08
WeightsProprietaryProprietary
Context window128K500K
Max output16K500K
Input $ / M tokens$1.75$2
Output $ / M tokens$14$6
Results tracked1852

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Category by category

Coding Grok 4.5 leads

GPT-5.3 Chat: 40.8 (#124), Grok 4.5: 51.7 (#34)

BenchmarkGPT-5.3 ChatGrok 4.5
LMArena Coding14081473
DeepSWE—53.8%
FrontierCode—42.4%
LMArena WebDev—1552
SciCode—54.1%
WeirdML—46.4%
ALE-Bench—1,309

Agentic & Tool Use Not comparable

GPT-5.3 Chat: —, Grok 4.5: 44.4 (#15)

BenchmarkGPT-5.3 ChatGrok 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-5.3 Chat: 27.3 (#105), Grok 4.5: 56.0 (#23)

BenchmarkGPT-5.3 ChatGrok 4.5
LMArena Hard Prompts13991462
ARC-AGI-2—52.6%
SimpleBench—70%
Kagi LLM Benchmark—83.5%
NYT Connections (extended)—79.9%
ARC-AGI-1—87.2%
CritPt—15.4%
Chess Puzzles—36%
DTBench—96.5%
LMCA—45.2%
Surface Evolver Bench—74.4%
Epoch Capabilities Index—154.02

Math Grok 4.5 leads

GPT-5.3 Chat: 35.4 (#146), Grok 4.5: 60.7 (#29)

BenchmarkGPT-5.3 ChatGrok 4.5
LMArena Math13891457
FrontierMath (Tiers 1-3)—57.2%
FrontierMath Tier 4—24.4%
OTIS Mock AIME 2024-2025—97.8%
ProofBench—31%

Knowledge Grok 4.5 leads

GPT-5.3 Chat: 38.2 (#137), Grok 4.5: 62.3 (#21)

BenchmarkGPT-5.3 ChatGrok 4.5
LMArena Expert13971466
GPQA Diamond—93.4%
SimpleQA Verified—48.3%

Multimodal Not comparable

GPT-5.3 Chat: —, Grok 4.5: 37.8 (#63)

BenchmarkGPT-5.3 ChatGrok 4.5
LMArena Vision—1287
Blueprint-Bench 2—27.3%
Furniture Assembly—22.5%
LMArena Document—1452

Multilingual Grok 4.5 leads

GPT-5.3 Chat: 50.5 (#119), Grok 4.5: 54.5 (#43)

BenchmarkGPT-5.3 ChatGrok 4.5
LMArena Non-English13831439
LMArena Chinese14331497
LMArena French13981458
LMArena German13841448
LMArena Japanese13511425
LMArena Korean13471402
LMArena Russian14001447
LMArena Spanish13711452

Instruction Following Grok 4.5 leads

GPT-5.3 Chat: 73.0 (#124), Grok 4.5: 76.3 (#45)

BenchmarkGPT-5.3 ChatGrok 4.5
LMArena Instruction Following13781446

Long Context Grok 4.5 leads

GPT-5.3 Chat: 42.6 (#115), Grok 4.5: 44.8 (#54)

BenchmarkGPT-5.3 ChatGrok 4.5
LMArena Longer Query13961463

Writing & Preference Grok 4.5 leads

GPT-5.3 Chat: 63.3 (#65), Grok 4.5: 65.9 (#40)

BenchmarkGPT-5.3 ChatGrok 4.5
LMArena Text13891448
LMArena Creative Writing13561442
EQ-Bench Creative Writing16901579
LMArena Multi-Turn14131457

Frequently asked questions

Is GPT-5.3 Chat better than Grok 4.5?

Grok 4.5 is the stronger model overall, scoring 55.0 to 42.1 on the Noometry Index.

Which is cheaper, GPT-5.3 Chat or Grok 4.5?

Grok 4.5 is cheaper. It lists at $2 per million input tokens and $6 per million output tokens; GPT-5.3 Chat lists at $1.75 and $14.

Is GPT-5.3 Chat or Grok 4.5 better for coding?

Grok 4.5 scores higher on coding benchmarks: 51.7 versus 40.8 in the Noometry coding category.

Which has the bigger context window?

Grok 4.5 does, with 500K tokens against 128K.

How many benchmarks do GPT-5.3 Chat and Grok 4.5 share?

18 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and Grok 4.5 has 52.

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