Noometry

Model comparison

GPT-5.6 Terra vs GPT-6 Luna

GPT-5.6 Terra is the stronger model overall, scoring 59.2 to 53.3 on the Noometry Index. GPT-6 Luna costs 23× less per token, which makes it the better buy when GPT-5.6 Terra's lead doesn't matter for your workload.

Last verified . 42 shared benchmarks.

GPT-5.6 Terra OpenAI

59.2

Rank #17 Confirmed

GPT-6 Luna OpenAI

53.3

Rank #36 Confirmed

Summary

  • They share 42 benchmarks with published results for both. GPT-5.6 Terra scores higher in 10 categories and GPT-6 Luna in 0 categories; 10 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where GPT-5.6 Terra leads 60.7 to 48.2.
  • The biggest single-benchmark swing is Mystery Game Puzzles: 35% for GPT-5.6 Terra and 7% for GPT-6 Luna.
  • GPT-6 Luna is cheaper at $0.10 / $0.50 per million input/output tokens, against $2 / $12 for GPT-5.6 Terra.

Side by side

GPT-5.6 TerraGPT-6 Luna
ProviderOpenAIOpenAI
Noometry Index59.253.3
Released2026-07-092026-09-22
WeightsProprietaryProprietary
Context window1.05M1.05M
Max output128K128K
Input $ / M tokens$2$0.10
Output $ / M tokens$12$0.50
Results tracked5242

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Category by category

Coding GPT-5.6 Terra leads

GPT-5.6 Terra: 57.7 (#19), GPT-6 Luna: 55.5 (#25)

BenchmarkGPT-5.6 TerraGPT-6 Luna
DeepSWE69.6%66.6%
FrontierCode41.3%42.4%
LMArena WebDev15221581
SciCode55%54.6%
LMArena Coding14841439
ALE-Bench1,9511,577
CursorBench41.3%—
WeirdML78.3%—

Agentic & Tool Use GPT-5.6 Terra leads

GPT-5.6 Terra: 40.1 (#25), GPT-6 Luna: 33.3 (#54)

BenchmarkGPT-5.6 TerraGPT-6 Luna
APEX-Agents58.2%44.3%
GDP.pdf24.7%23%
BALROG53.2%—
Vending-Bench 27,343—

Reasoning GPT-5.6 Terra leads

GPT-5.6 Terra: 60.7 (#21), GPT-6 Luna: 48.2 (#41)

BenchmarkGPT-5.6 TerraGPT-6 Luna
ARC-AGI-283.9%59.3%
NYT Connections (extended)78.4%68.7%
ARC-AGI-196.5%86.7%
CritPt30%19.4%
Chess Puzzles54%31%
LMArena Hard Prompts14681411
Mystery Game Puzzles35%7%
DTBench93.3%90.1%
LMCA55%44.5%
Epoch Capabilities Index159.62156.28
SimpleBench48.9%—
Kagi LLM Benchmark51.3%—
Surface Evolver Bench83.8%—

Math GPT-5.6 Terra leads

GPT-5.6 Terra: 81.6 (#12), GPT-6 Luna: 76.1 (#15)

BenchmarkGPT-5.6 TerraGPT-6 Luna
FrontierMath (Tiers 1-3)86%78.9%
FrontierMath Tier 470.7%56.1%
OTIS Mock AIME 2024-202599.7%98.9%
ProofBench74%64%
LMArena Math14661416

Knowledge GPT-5.6 Terra leads

GPT-5.6 Terra: 61.2 (#30), GPT-6 Luna: 57.0 (#41)

BenchmarkGPT-5.6 TerraGPT-6 Luna
GPQA Diamond93.3%90.5%
SimpleQA Verified43.2%41.4%
LMArena Expert14921444

Multimodal GPT-5.6 Terra leads

GPT-5.6 Terra: 47.3 (#11), GPT-6 Luna: 42.4 (#30)

BenchmarkGPT-5.6 TerraGPT-6 Luna
LMArena Vision12711217
Blueprint-Bench 230.8%31.2%
Furniture Assembly54.2%44.2%
LMArena Document1472—

Multilingual GPT-5.6 Terra leads

GPT-5.6 Terra: 54.4 (#44), GPT-6 Luna: 50.5 (#117)

BenchmarkGPT-5.6 TerraGPT-6 Luna
LMArena Non-English14391386
LMArena Chinese15131433
LMArena French14711420
LMArena German14601369
LMArena Japanese14571369
LMArena Korean14251360
LMArena Russian14501394
LMArena Spanish14481393

Instruction Following GPT-5.6 Terra leads

GPT-5.6 Terra: 76.4 (#40), GPT-6 Luna: 74.3 (#99)

BenchmarkGPT-5.6 TerraGPT-6 Luna
LMArena Instruction Following14541409

Long Context GPT-5.6 Terra leads

GPT-5.6 Terra: 44.4 (#68), GPT-6 Luna: 43.0 (#111)

BenchmarkGPT-5.6 TerraGPT-6 Luna
LMArena Longer Query14511409

Writing & Preference GPT-5.6 Terra leads

GPT-5.6 Terra: 70.2 (#23), GPT-6 Luna: 58.3 (#119)

BenchmarkGPT-5.6 TerraGPT-6 Luna
LMArena Text14471391
LMArena Creative Writing14101363
LMArena Multi-Turn14491396
EQ-Bench Creative Writing1855—
EQ-Bench 41234—

Frequently asked questions

Is GPT-5.6 Terra better than GPT-6 Luna?

GPT-5.6 Terra is the stronger model overall, scoring 59.2 to 53.3 on the Noometry Index. GPT-6 Luna costs 23× less per token, which makes it the better buy when GPT-5.6 Terra's lead doesn't matter for your workload.

Which is cheaper, GPT-5.6 Terra or GPT-6 Luna?

GPT-6 Luna is cheaper. It lists at $0.10 per million input tokens and $0.50 per million output tokens; GPT-5.6 Terra lists at $2 and $12.

Is GPT-5.6 Terra or GPT-6 Luna better for coding?

GPT-5.6 Terra scores higher on coding benchmarks: 57.7 versus 55.5 in the Noometry coding category.

Which has the bigger context window?

Both accept 1.05M tokens.

How many benchmarks do GPT-5.6 Terra and GPT-6 Luna share?

42 benchmarks have published results for both models. GPT-5.6 Terra has 52 scored results on Noometry and GPT-6 Luna has 42.

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