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Claude Opus 5.5 vs GPT-6 Luna

Claude Opus 5.5 leads GPT-6 Luna on coding, 88.8 to 57.3 on the Vibe Coding Index, and GPT-6 Luna costs 40.0x less per output token ($0.50 vs $20.00 per million). Updated October 22, 2026; 97 benchmarks have a result for both.

Replace Claude Opus 5.5 Replace GPT-6 Luna
Claude Opus 5.5Anthropic
Coding
88.8
Overall
87.1
Output $/M
$20.00
95
GPT-6 LunaOpenAI
Coding
57.3
Overall
59.7
Output $/M
$0.50
2
vs boards won of 97 shared

Claude Opus 5.5 or GPT-6 Luna: which to pick

Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 57.3 for GPT-6 Luna.

Pick GPT-6 Luna for output tokens 40.0x cheaper ($0.50 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).

Model AClaude Opus 5.5Anthropic88.8/1005 independent benchmarksNo cost per solved taskModel BGPT-6 LunaOpenAI57.3/1005 independent benchmarksNo cost per solved task
Shared results
97
Claude Opus 5.5 only
12
GPT-6 Luna only
6
Like-for-like categories
8 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

At a glance

Coding index
Claude Opus 5.5 88.8 from 5 benchmarks, GPT-6 Luna 57.3 from 5 benchmarks.
Widest category
Reasoning, 22.9 points apart on average over 13 shared benchmarks.
Widest single gap
Terminal-Bench 4 (Vals AI): Claude Opus 5.5 65.2% against GPT-6 Luna 13.6%, 68.7 points apart on a 0 to 100 scale.
Output price
Claude Opus 5.5 $20.00 against GPT-6 Luna $0.50 per million output tokens, 40.0x apart.
Context window
Claude Opus 5.5 takes 1M tokens, GPT-6 Luna 1.05M.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
CategoryClaude Opus 5.5BarsGPT-6 LunaTies
Coding171
Intelligence20
Agentic work160
Reasoning130
Math60
Knowledge70
Web design80
General261
All shared boards952
CodingLike-for-likeSix of these boards feed the Vibe Coding Index171
Coding benchmarks for Claude Opus 5.5 and GPT-6 Luna
BenchmarkClaude Opus 5.5GPT-6 LunaLeader
LiveBench coding96.3%84.5%Claude Opus 5.5
LMArena WebDev18071578Claude Opus 5.5
Terminal-Bench 4 (Vals AI)65.2%13.6%Claude Opus 5.5
Vibe Code Bench (Vals AI)90.3%81.7%Claude Opus 5.5
Code migration (Vals AI)66.7%42.5%Claude Opus 5.5
ProgramBench (Vals AI)18.5%0.5%Claude Opus 5.5
IOI (Vals AI)95.1%55.6%Claude Opus 5.5
Terminal-Bench 2.1 (Vals AI)87.6%73.0%Claude Opus 5.5
SWE-bench Multimodal (Vals AI)70.2%37.5%Claude Opus 5.5
Vibe Code Bench 1-100 (Vals AI)30.4%Not measuredOnly Claude Opus 5.5 measured
CyberBench (Vals AI)74.6%76.3%GPT-6 Luna
SciCode66.9%54.6%Claude Opus 5.5
FrontierCode54.6%42.4%Claude Opus 5.5
FrontierSWE62.3%Not measuredOnly Claude Opus 5.5 measured
MirrorCode77.4%Not measuredOnly Claude Opus 5.5 measured
ALE-Bench2147.41576.9Claude Opus 5.5
LMArena Text: coding15451437Claude Opus 5.5
LMArena Text: software and IT15381423Claude Opus 5.5
LMArena WebDev: React18551573Claude Opus 5.5
LMArena WebDev: HTML17531595Claude Opus 5.5
LMArena WebDev: from an image17531571Claude Opus 5.5
SciCode18.5%Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 17 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Opus 5.5 and GPT-6 Luna
BenchmarkClaude Opus 5.5GPT-6 LunaLeader
AA Intelligence Index57.638.1Claude Opus 5.5
Epoch Capabilities Index168.8156.8Claude Opus 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index160
Agentic work benchmarks for Claude Opus 5.5 and GPT-6 Luna
BenchmarkClaude Opus 5.5GPT-6 LunaLeader
Design Arena: agents building web apps13161191Claude Opus 5.5
Design Arena: agents building full-stack appsNot measured1158Only GPT-6 Luna measured
Design Arena: agents building mobile apps13081134Claude Opus 5.5
Design Arena: spreadsheets1368Not measuredOnly Claude Opus 5.5 measured
LiveBench research85.0%43.5%Claude Opus 5.5
LiveBench browser80.0%72.0%Claude Opus 5.5
LiveBench long agentic85.0%48.1%Claude Opus 5.5
SREBench (Vals AI)33.6%2.7%Claude Opus 5.5
Finance Agent (Vals AI)58.6%49.9%Claude Opus 5.5
Tax Agent Bench (Vals AI)45.6%19.9%Claude Opus 5.5
Legal Research Bench (Vals AI)50.5%30.3%Claude Opus 5.5
Harvey's Legal Agent Benchmark (Vals AI)9.2%4.2%Claude Opus 5.5
Excel Modeling Benchmark (Vals AI)75.9%68.5%Claude Opus 5.5
BioMysteryBench (Vals AI)79.3%61.5%Claude Opus 5.5
Terminal-Bench-Science (Vals AI)47.1%4.3%Claude Opus 5.5
Vals Science Index58.7%28.4%Claude Opus 5.5
Time Horizon Index (Vals AI)91.3%Not measuredOnly Claude Opus 5.5 measured
CUA-bench (Vals AI)14.0%Not measuredOnly Claude Opus 5.5 measured
Robo-bench (Vals AI)14.6%Not measuredOnly Claude Opus 5.5 measured
APEX-Agents73.5%44.3%Claude Opus 5.5
Remote Labor Index21.3%Not measuredOnly Claude Opus 5.5 measured
SpireClimb3.3%0.0%Claude Opus 5.5
Vending-Bench 2$9,235Not measuredOnly Claude Opus 5.5 measured
LMArena Search1213Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 17 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index130
Reasoning benchmarks for Claude Opus 5.5 and GPT-6 Luna
BenchmarkClaude Opus 5.5GPT-6 LunaLeader
LiveBench reasoning92.2%81.8%Claude Opus 5.5
MysteryMechanism (Vals AI)49.5%19.4%Claude Opus 5.5
Humanity's Last Exam (Artificial Analysis run)61.4%38.5%Claude Opus 5.5
GPQA Diamond (Epoch AI run)90.6%90.5%Claude Opus 5.5
ARC-AGI98.5%86.7%Claude Opus 5.5
ARC-AGI-293.3%59.3%Claude Opus 5.5
Chess puzzles67.0%36.0%Claude Opus 5.5
Mystery game puzzles71.0%7.0%Claude Opus 5.5
EBR-bench71.4%Not measuredOnly Claude Opus 5.5 measured
LMArena Text: hard prompts15361410Claude Opus 5.5
LMArena Text: expert15491442Claude Opus 5.5
LMArena Text: hard prompts in English15351410Claude Opus 5.5
LMArena Vision: diagrams13451245Claude Opus 5.5
LMArena Vision: homework13621261Claude Opus 5.5
Neither model has a result on the other 8 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Opus 5.5 and GPT-6 Luna
BenchmarkClaude Opus 5.5GPT-6 LunaLeader
OTIS Mock AIME100.0%98.9%Claude Opus 5.5
FrontierMath, tiers 1 to 391.2%78.9%Claude Opus 5.5
FrontierMath, tier 495.0%56.1%Claude Opus 5.5
ProofBench100.0%64.0%Claude Opus 5.5
LMArena Text: math15181409Claude Opus 5.5
LMArena Text: mathematical work15161427Claude Opus 5.5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index70
Knowledge benchmarks for Claude Opus 5.5 and GPT-6 Luna
BenchmarkClaude Opus 5.5GPT-6 LunaLeader
MedCode (Vals AI)49.8%44.7%Claude Opus 5.5
SimpleQA Verified72.2%41.4%Claude Opus 5.5
LMArena Text: science15241386Claude Opus 5.5
LMArena Text: medicine and healthcare15091352Claude Opus 5.5
LMArena Text: legal and government15181400Claude Opus 5.5
LMArena Text: business and finance14941388Claude Opus 5.5
FACTS Benchmark Suite65.3%63.3%Claude Opus 5.5
Neither model has a result on the other 11 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index80
Web design benchmarks for Claude Opus 5.5 and GPT-6 Luna
BenchmarkClaude Opus 5.5GPT-6 LunaLeader
Design Arena: websites13351271Claude Opus 5.5
Design Arena: UI components13851295Claude Opus 5.5
Design Arena: game dev14611257Claude Opus 5.5
Design Arena: data viz13971216Claude Opus 5.5
Design Arena: 3D14761218Claude Opus 5.5
Design Arena: all code categories13901270Claude Opus 5.5
Design Arena: SVG13291252Claude Opus 5.5
Design Arena: ASCII artNot measured1153Only GPT-6 Luna measured
LiveBench design86.9%82.5%Claude Opus 5.5
GeneralLike-for-likePublic boards, shown as published, kept out of the index261
General benchmarks for Claude Opus 5.5 and GPT-6 Luna
BenchmarkClaude Opus 5.5GPT-6 LunaLeader
Vals Index70.2%52.3%Claude Opus 5.5
LiveBench data analysis80.3%73.4%Claude Opus 5.5
Public Benefits Bench (Vals AI)70.6%57.6%Claude Opus 5.5
SAGE (Vals AI)45.8%48.1%GPT-6 Luna
MedScribe (Vals AI)91.4%83.7%Claude Opus 5.5
Long context reasoning (AA-LCR)84.7%83.3%Claude Opus 5.5
DTBench98.9%90.1%Claude Opus 5.5
LMCA68.2%44.5%Claude Opus 5.5
Furniture assembly83.3%44.2%Claude Opus 5.5
LMArena Text15161389Claude Opus 5.5
LMArena Text: instruction following15371408Claude Opus 5.5
LMArena Text: creative writing15351363Claude Opus 5.5
LMArena Vision13211216Claude Opus 5.5
LMArena Text: English15191393Claude Opus 5.5
LMArena Text: non-English15071381Claude Opus 5.5
LMArena Text: Chinese15821427Claude Opus 5.5
LMArena Text: GermanNot measured1376Only GPT-6 Luna measured
LMArena Text: Japanese15341369Claude Opus 5.5
LMArena Text: KoreanNot measured1359Only GPT-6 Luna measured
LMArena Text: French14931408Claude Opus 5.5
LMArena Text: Spanish15081391Claude Opus 5.5
LMArena Text: Russian15171392Claude Opus 5.5
LMArena Text: PolishNot measured1383Only GPT-6 Luna measured
LMArena Text: multi-turn15011392Claude Opus 5.5
LMArena Text: longer queries15321408Claude Opus 5.5
LMArena Text: writing and language15321384Claude Opus 5.5
LMArena Text: entertainment and media15151364Claude Opus 5.5
LMArena Vision: English13171204Claude Opus 5.5
LMArena Vision: ChineseNot measured1266Only GPT-6 Luna measured
LMArena Vision: reading text13261225Claude Opus 5.5
LMArena Vision: creative writing13201205Claude Opus 5.5
Neither model has a result on the other 15 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Opus 5.5 and GPT-6 Luna
BenchmarkClaude Opus 5.5GPT-6 LunaLeader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

Claude Opus 5.5$0.014Fits in one request
GPT-6 Luna$0.0003Fits in one request

GPT-6 Luna costs less

Repository review

50K input + 3K output tokens

Claude Opus 5.5$0.260Fits in one request
GPT-6 Luna$0.0065Fits in one request

GPT-6 Luna costs less

Agent loop

200K input + 10K output tokens

Claude Opus 5.5$1.00Fits in one request
GPT-6 Luna$0.025Fits in one request

GPT-6 Luna costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of Claude Opus 5.5 and GPT-6 Luna
SpecificationAnthropic Claude Opus 5.5OpenAI GPT-6 Luna
MakerAnthropicOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 22, 2026September 22, 2026
Context window1M1.05M
Input $/Mtok$4.00$0.10
Output $/Mtok$20.00$0.50
Coding index88.857.3
Independent measurements behind it55
Cost per solved taskNot computableNot computable
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 5.5 better than GPT-6 Luna for coding?

Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 57.3 for GPT-6 Luna. Pick GPT-6 Luna for output tokens 40.0x cheaper ($0.50 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).

Which is cheaper, Claude Opus 5.5 or GPT-6 Luna?

Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; GPT-6 Luna costs $0.10 and $0.50. Cost per solved task is known for neither of them.

Which has the bigger context window, Claude Opus 5.5 or GPT-6 Luna?

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

How many benchmarks is the Claude Opus 5.5 vs GPT-6 Luna comparison based on?

97 benchmarks have a result for both models as of October 22, 2026. Claude Opus 5.5's coding index rests on 5 independent benchmarks and GPT-6 Luna's on 5. Where only one model has a result, the page says so instead of naming a winner.

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