Noometry

Model comparison

GPT-5.5 vs Grok 4.20 (Non-Reasoning)

GPT-5.5 is the stronger model overall, scoring 63.4 to 48.6 on the Noometry Index. Grok 4.20 (Non-Reasoning) costs 7.2× less per token, which makes it the better buy when GPT-5.5's lead doesn't matter for your workload.

Last verified . 44 shared benchmarks.

GPT-5.5 OpenAI

63.4

Rank #9 Confirmed

Grok 4.20 (Non-Reasoning) xAI

48.6

Rank #54 Confirmed

Summary

  • They share 44 benchmarks with published results for both. GPT-5.5 scores higher in 10 categories and Grok 4.20 (Non-Reasoning) in 0 categories; 10 gaps are clear of the uncertainty.
  • The widest gap is in math, where GPT-5.5 leads 81.7 to 48.2.
  • The biggest single-benchmark swing is FrontierMath Tier 4: 72.5% for GPT-5.5 and 17.1% for Grok 4.20 (Non-Reasoning).
  • Grok 4.20 (Non-Reasoning) is cheaper at $1.25 / $2.50 per million input/output tokens, against $5 / $30 for GPT-5.5.
  • GPT-5.5 accepts more context: 1.05M tokens versus 1M.

Side by side

GPT-5.5Grok 4.20 (Non-Reasoning)
ProviderOpenAIxAI
Noometry Index63.448.6
Released2026-04-232026-02-17
WeightsProprietaryProprietary
Context window1.05M1M
Max output128K30K
Input $ / M tokens$5$1.25
Output $ / M tokens$30$2.50
Results tracked7146

Sponsored placements are available on pages like this one. Advertise on Noometry

Category by category

Coding GPT-5.5 leads

GPT-5.5: 58.2 (#17), Grok 4.20 (Non-Reasoning): 42.1 (#112)

BenchmarkGPT-5.5Grok 4.20 (Non-Reasoning)
LMArena WebDev15131375
WeirdML84.9%52.3%
LMArena Coding14941459
ALE-Bench1,9431,150
SWE-bench Verified80.6%—
DeepSWE67%—
FrontierCode43%—
SciCode56.1%—
GSO40.2%—
MirrorCode10%—

Agentic & Tool Use GPT-5.5 leads

GPT-5.5: 50.7 (#6), Grok 4.20 (Non-Reasoning): 34.4 (#46)

BenchmarkGPT-5.5Grok 4.20 (Non-Reasoning)
Terminal-Bench84.7%57.3%
τ²-bench Banking44.6%18%
LMArena Search12421189
Vending-Bench 27,5244,663
APEX-Agents55.1%—
OSWorld 2.013%—
Remote Labor Index6.3%—
DeepResearch Bench54%—
PostTrainBench27.2%—
ExploitBench47.4%—
GBAEval53.2%—
GDP.pdf26%—

Reasoning GPT-5.5 leads

GPT-5.5: 72.8 (#11), Grok 4.20 (Non-Reasoning): 52.3 (#32)

BenchmarkGPT-5.5Grok 4.20 (Non-Reasoning)
ARC-AGI-285%65.1%
Kagi LLM Benchmark88.8%75%
NYT Connections (extended)96.2%85.4%
ARC-AGI-195%89.5%
Chess Puzzles54%24%
LMArena Hard Prompts14891451
DTBench96%90.1%
LMCA54.3%38.7%
Epoch Capabilities Index159.1151.98
ForecastBench60.661.4
SimpleBench69%—
CritPt27.1%—
Thematic Generalization—63.8%
EBR-Bench34.3%—
Mystery Game Puzzles56%—
Surface Evolver Bench88.1%—
Bench to the Future 30.14—

Math GPT-5.5 leads

GPT-5.5: 81.7 (#11), Grok 4.20 (Non-Reasoning): 48.2 (#65)

BenchmarkGPT-5.5Grok 4.20 (Non-Reasoning)
FrontierMath (Tiers 1-3)85.3%44.9%
FrontierMath Tier 472.5%17.1%
OTIS Mock AIME 2024-2025100%92.2%
ProofBench50%14%
LMArena Math14861455
MathArena Final-Answer Competitions94.3%—
FrontierMath (Feb 2025 set)51.7%—
FrontierMath Erdős0%—
FrontierMath Tier 4 (v1)35.4%—

Knowledge GPT-5.5 leads

GPT-5.5: 64.4 (#17), Grok 4.20 (Non-Reasoning): 52.8 (#60)

BenchmarkGPT-5.5Grok 4.20 (Non-Reasoning)
GPQA Diamond94%89.3%
SimpleQA Verified63%30.2%
LMArena Expert15081439
Vectara Hallucination Rate9.3%—

Multimodal GPT-5.5 leads

GPT-5.5: 46.9 (#12), Grok 4.20 (Non-Reasoning): 33.3 (#98)

BenchmarkGPT-5.5Grok 4.20 (Non-Reasoning)
LMArena Vision12971263
Blueprint-Bench 236.2%0%
LMArena Document14861416
Furniture Assembly44.2%—

Multilingual GPT-5.5 leads

GPT-5.5: 56.4 (#20), Grok 4.20 (Non-Reasoning): 54.5 (#40)

BenchmarkGPT-5.5Grok 4.20 (Non-Reasoning)
LMArena Non-English14671441
LMArena Chinese15331481
LMArena French14861476
LMArena German14801465
LMArena Japanese14981449
LMArena Korean14601417
LMArena Russian14731458
LMArena Spanish14681443

Instruction Following GPT-5.5 leads

GPT-5.5: 77.5 (#18), Grok 4.20 (Non-Reasoning): 74.8 (#83)

BenchmarkGPT-5.5Grok 4.20 (Non-Reasoning)
LMArena Instruction Following14791420

Long Context GPT-5.5 leads

GPT-5.5: 48.3 (#12), Grok 4.20 (Non-Reasoning): 45.5 (#34)

BenchmarkGPT-5.5Grok 4.20 (Non-Reasoning)
CL-bench Life22.2%11.9%
LMArena Longer Query14841437
CL-bench—22.2%

Writing & Preference GPT-5.5 leads

GPT-5.5: 72.7 (#13), Grok 4.20 (Non-Reasoning): 65.7 (#44)

BenchmarkGPT-5.5Grok 4.20 (Non-Reasoning)
LMArena Text14721451
LMArena Creative Writing14551438
EQ-Bench Creative Writing18441574
LMArena Multi-Turn14761456
EQ-Bench 41315—

Frequently asked questions

Is GPT-5.5 better than Grok 4.20 (Non-Reasoning)?

GPT-5.5 is the stronger model overall, scoring 63.4 to 48.6 on the Noometry Index. Grok 4.20 (Non-Reasoning) costs 7.2× less per token, which makes it the better buy when GPT-5.5's lead doesn't matter for your workload.

Which is cheaper, GPT-5.5 or Grok 4.20 (Non-Reasoning)?

Grok 4.20 (Non-Reasoning) is cheaper. It lists at $1.25 per million input tokens and $2.50 per million output tokens; GPT-5.5 lists at $5 and $30.

Is GPT-5.5 or Grok 4.20 (Non-Reasoning) better for coding?

GPT-5.5 scores higher on coding benchmarks: 58.2 versus 42.1 in the Noometry coding category.

Which has the bigger context window?

GPT-5.5 does, with 1.05M tokens against 1M.

How many benchmarks do GPT-5.5 and Grok 4.20 (Non-Reasoning) share?

44 benchmarks have published results for both models. GPT-5.5 has 71 scored results on Noometry and Grok 4.20 (Non-Reasoning) has 46.

Related comparisons

Go deeper