Noometry

Model comparison

Claude Sonnet 5.5 vs GPT-6 Luna

Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 53.3 on the Noometry Index. GPT-6 Luna costs 20× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.

Last verified . 29 shared benchmarks.

Claude Sonnet 5.5 Anthropic

61.9

Rank #10 Confirmed

GPT-6 Luna OpenAI

53.3

Rank #36 Confirmed

Summary

  • They share 29 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 10 categories and GPT-6 Luna in 0 categories; 10 gaps are clear of the uncertainty.
  • The widest gap is in math, where Claude Sonnet 5.5 leads 87.9 to 76.1.
  • The biggest single-benchmark swing is Mystery Game Puzzles: 65% for Claude Sonnet 5.5 and 7% for GPT-6 Luna.
  • GPT-6 Luna is cheaper at $0.10 / $0.50 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
  • GPT-6 Luna accepts more context: 1.05M tokens versus 1M.

Side by side

Claude Sonnet 5.5GPT-6 Luna
ProviderAnthropicOpenAI
Noometry Index61.953.3
Released2026-09-282026-09-22
WeightsProprietaryProprietary
Context window1M1.05M
Max output128K128K
Input $ / M tokens$2$0.10
Output $ / M tokens$10$0.50
Results tracked3242

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Category by category

Coding Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 67.3 (#6), GPT-6 Luna: 55.5 (#25)

BenchmarkClaude Sonnet 5.5GPT-6 Luna
FrontierCode52.1%42.4%
LMArena WebDev17741581
SciCode61%54.6%
LMArena Coding15131439
ALE-Bench1,8191,577
DeepSWE—66.6%
CursorBench55.5%—
FrontierSWE61.9%—

Agentic & Tool Use Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 45.0 (#16), GPT-6 Luna: 33.3 (#54)

BenchmarkClaude Sonnet 5.5GPT-6 Luna
APEX-Agents75.5%44.3%
GDP.pdf—23%

Reasoning Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 54.0 (#28), GPT-6 Luna: 48.2 (#41)

BenchmarkClaude Sonnet 5.5GPT-6 Luna
NYT Connections (extended)80.5%68.7%
CritPt31.4%19.4%
LMArena Hard Prompts14951411
Mystery Game Puzzles65%7%
Epoch Capabilities Index165.03156.28
ARC-AGI-2—59.3%
ARC-AGI-1—86.7%
Chess Puzzles—31%
DTBench—90.1%
LMCA—44.5%

Math Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 87.9 (#6), GPT-6 Luna: 76.1 (#15)

BenchmarkClaude Sonnet 5.5GPT-6 Luna
FrontierMath (Tiers 1-3)88.8%78.9%
FrontierMath Tier 480.5%56.1%
OTIS Mock AIME 2024-2025100%98.9%
ProofBench100%64%
LMArena Math15101416
FrontierMath Erdős2.9%—

Knowledge Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 66.0 (#12), GPT-6 Luna: 57.0 (#41)

BenchmarkClaude Sonnet 5.5GPT-6 Luna
GPQA Diamond95.6%90.5%
SimpleQA Verified46.5%41.4%
LMArena Expert15401444

Multimodal Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 51.5 (#6), GPT-6 Luna: 42.4 (#30)

BenchmarkClaude Sonnet 5.5GPT-6 Luna
LMArena Vision12891217
Furniture Assembly75%44.2%
Blueprint-Bench 2—31.2%

Multilingual Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 55.3 (#30), GPT-6 Luna: 50.5 (#117)

BenchmarkClaude Sonnet 5.5GPT-6 Luna
LMArena Non-English14521386
LMArena Chinese15221433
LMArena Russian14511394
LMArena French—1420
LMArena German—1369
LMArena Japanese—1369
LMArena Korean—1360
LMArena Spanish—1393

Instruction Following Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 78.3 (#11), GPT-6 Luna: 74.3 (#99)

BenchmarkClaude Sonnet 5.5GPT-6 Luna
LMArena Instruction Following14951409

Long Context Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 45.9 (#28), GPT-6 Luna: 43.0 (#111)

BenchmarkClaude Sonnet 5.5GPT-6 Luna
LMArena Longer Query14981409

Writing & Preference Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 66.0 (#40), GPT-6 Luna: 58.3 (#119)

BenchmarkClaude Sonnet 5.5GPT-6 Luna
LMArena Text14711391
LMArena Creative Writing14651363
LMArena Multi-Turn14741396

Frequently asked questions

Is Claude Sonnet 5.5 better than GPT-6 Luna?

Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 53.3 on the Noometry Index. GPT-6 Luna costs 20× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.

Which is cheaper, Claude Sonnet 5.5 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; Claude Sonnet 5.5 lists at $2 and $10.

Is Claude Sonnet 5.5 or GPT-6 Luna better for coding?

Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 55.5 in the Noometry coding category.

Which has the bigger context window?

GPT-6 Luna does, with 1.05M tokens against 1M.

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

29 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and GPT-6 Luna has 42.

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