Noometry

Model comparison

GPT-5.5 Instant vs GPT-6 Luna

GPT-6 Luna is the stronger model overall, scoring 53.3 to 42.7 on the Noometry Index.

Last verified . 26 shared benchmarks.

GPT-5.5 Instant OpenAI

42.7

Rank #110 Confirmed

GPT-6 Luna OpenAI

53.3

Rank #36 Confirmed

Summary

  • They share 26 benchmarks with published results for both. GPT-5.5 Instant scores higher in 3 categories and GPT-6 Luna in 6 categories; 7 gaps are clear of the uncertainty.
  • The widest gap is in math, where GPT-6 Luna leads 76.1 to 26.5.
  • The biggest single-benchmark swing is FrontierMath Tier 4: 2.4% for GPT-5.5 Instant and 56.1% for GPT-6 Luna.

Side by side

GPT-5.5 InstantGPT-6 Luna
ProviderOpenAIOpenAI
Noometry Index42.753.3
Released2026-05-052026-09-22
WeightsProprietaryProprietary
Context window—1.05M
Max output—128K
Input $ / M tokens—$0.10
Output $ / M tokens—$0.50
Results tracked2742

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Category by category

Coding GPT-6 Luna leads

GPT-5.5 Instant: 44.3 (#74), GPT-6 Luna: 55.5 (#25)

BenchmarkGPT-5.5 InstantGPT-6 Luna
SciCode48.6%54.6%
LMArena Coding14331439
DeepSWE—66.6%
FrontierCode—42.4%
LMArena WebDev—1581
ALE-Bench—1,577

Agentic & Tool Use Not comparable

GPT-5.5 Instant: —, GPT-6 Luna: 33.3 (#54)

BenchmarkGPT-5.5 InstantGPT-6 Luna
APEX-Agents—44.3%
GDP.pdf—23%

Reasoning GPT-6 Luna leads

GPT-5.5 Instant: 24.9 (#155), GPT-6 Luna: 48.2 (#41)

BenchmarkGPT-5.5 InstantGPT-6 Luna
CritPt0%19.4%
Chess Puzzles12%31%
LMArena Hard Prompts14261411
Epoch Capabilities Index142.52156.28
ARC-AGI-2—59.3%
NYT Connections (extended)—68.7%
ARC-AGI-1—86.7%
Mystery Game Puzzles—7%
DTBench—90.1%
LMCA—44.5%

Math GPT-6 Luna leads

GPT-5.5 Instant: 26.5 (#259), GPT-6 Luna: 76.1 (#15)

BenchmarkGPT-5.5 InstantGPT-6 Luna
FrontierMath (Tiers 1-3)26.3%78.9%
FrontierMath Tier 42.4%56.1%
OTIS Mock AIME 2024-202568.1%98.9%
LMArena Math14201416
ProofBench—64%

Knowledge GPT-6 Luna leads

GPT-5.5 Instant: 48.9 (#74), GPT-6 Luna: 57.0 (#41)

BenchmarkGPT-5.5 InstantGPT-6 Luna
GPQA Diamond82.5%90.5%
LMArena Expert14091444
SimpleQA Verified—41.4%

Multimodal GPT-6 Luna leads

GPT-5.5 Instant: 40.0 (#52), GPT-6 Luna: 42.4 (#30)

BenchmarkGPT-5.5 InstantGPT-6 Luna
LMArena Vision12501217
Blueprint-Bench 2—31.2%
Furniture Assembly—44.2%
LMArena Document1403—

Multilingual GPT-5.5 Instant leads

GPT-5.5 Instant: 52.8 (#80), GPT-6 Luna: 50.5 (#117)

BenchmarkGPT-5.5 InstantGPT-6 Luna
LMArena Non-English14171386
LMArena Chinese14561433
LMArena French14281420
LMArena German14111369
LMArena Japanese14081369
LMArena Korean13921360
LMArena Russian14311394
LMArena Spanish14291393

Instruction Following Too close to call

GPT-5.5 Instant: 74.2 (#100), GPT-6 Luna: 74.3 (#99)

BenchmarkGPT-5.5 InstantGPT-6 Luna
LMArena Instruction Following14061409

Long Context Too close to call

GPT-5.5 Instant: 43.4 (#96), GPT-6 Luna: 43.0 (#111)

BenchmarkGPT-5.5 InstantGPT-6 Luna
LMArena Longer Query14221409

Writing & Preference GPT-5.5 Instant leads

GPT-5.5 Instant: 61.8 (#85), GPT-6 Luna: 58.3 (#119)

BenchmarkGPT-5.5 InstantGPT-6 Luna
LMArena Text14191391
LMArena Creative Writing14191363
LMArena Multi-Turn14331396

Frequently asked questions

Is GPT-5.5 Instant better than GPT-6 Luna?

GPT-6 Luna is the stronger model overall, scoring 53.3 to 42.7 on the Noometry Index.

Is GPT-5.5 Instant or GPT-6 Luna better for coding?

GPT-6 Luna scores higher on coding benchmarks: 55.5 versus 44.3 in the Noometry coding category.

How many benchmarks do GPT-5.5 Instant and GPT-6 Luna share?

26 benchmarks have published results for both models. GPT-5.5 Instant has 27 scored results on Noometry and GPT-6 Luna has 42.

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