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Claude Opus 5.5 vs GPT-5.6 Luna

Claude Opus 5.5 leads GPT-5.6 Luna on coding, 88.8 to 58.0 on the Vibe Coding Index, and GPT-5.6 Luna costs 16.7x less per output token ($1.20 vs $20.00 per million). Updated October 22, 2026; 94 benchmarks have a result for both.

Replace Claude Opus 5.5 Replace GPT-5.6 Luna
Claude Opus 5.5Anthropic
Coding
88.8
Overall
87.1
Output $/M
$20.00
93
GPT-5.6 LunaOpenAI
Coding
58.0
Overall
61.6
Output $/M
$1.20
1
vs boards won of 94 shared

Claude Opus 5.5 or GPT-5.6 Luna: which to pick

Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 58.0 for GPT-5.6 Luna, though on 5 benchmarks against 6.

Pick GPT-5.6 Luna for output tokens 16.7x cheaper ($1.20 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-5.6 LunaOpenAI58.0/1006 independent benchmarks$0.04 per solved task
Shared results
94
Claude Opus 5.5 only
15
GPT-5.6 Luna only
25
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-5.6 Luna 58.0 from 6 benchmarks.
Widest category
Agentic work, 26.2 points apart on average over 13 shared benchmarks.
Widest single gap
Terminal-Bench 4 (Vals AI): Claude Opus 5.5 65.2% against GPT-5.6 Luna 11.6%, 71.4 points apart on a 0 to 100 scale.
Output price
Claude Opus 5.5 $20.00 against GPT-5.6 Luna $1.20 per million output tokens, 16.7x apart.
Context window
Claude Opus 5.5 takes 1M tokens, GPT-5.6 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-5.6 LunaTies
Coding190
Intelligence20
Agentic work130
Reasoning121
Math60
Knowledge70
Web design80
General260
All shared boards931
CodingLike-for-likeSix of these boards feed the Vibe Coding Index190
Coding benchmarks for Claude Opus 5.5 and GPT-5.6 Luna
BenchmarkClaude Opus 5.5GPT-5.6 LunaLeader
LiveBench coding96.3%73.6%Claude Opus 5.5
LMArena WebDev18071518Claude Opus 5.5
AA Coding IndexNot measured71.4Only GPT-5.6 Luna measured
SWE-bench Verified (Vals AI)Not measured93.0%Only GPT-5.6 Luna measured
Terminal-Bench 4 (Vals AI)65.2%11.6%Claude Opus 5.5
Vibe Code Bench (Vals AI)90.3%77.1%Claude Opus 5.5
Code migration (Vals AI)66.7%44.5%Claude Opus 5.5
ProgramBench (Vals AI)18.5%0.0%Claude Opus 5.5
IOI (Vals AI)95.1%61.8%Claude Opus 5.5
Terminal-Bench 2.1 (Vals AI)87.6%79.0%Claude Opus 5.5
SWE-bench Multimodal (Vals AI)70.2%Not measuredOnly Claude Opus 5.5 measured
Vibe Code Bench 1-100 (Vals AI)30.4%22.6%Claude Opus 5.5
SkillsBench (Vals AI)Not measured60.5%Only GPT-5.6 Luna measured
CyberBench (Vals AI)74.6%73.6%Claude Opus 5.5
SciCode66.9%53.6%Claude Opus 5.5
FrontierCode54.6%39.8%Claude Opus 5.5
FrontierSWE62.3%Not measuredOnly Claude Opus 5.5 measured
WeirdMLNot measured60.9%Only GPT-5.6 Luna measured
MirrorCode77.4%Not measuredOnly Claude Opus 5.5 measured
ALE-Bench2147.41667.4Claude Opus 5.5
LMArena Text: coding15451466Claude Opus 5.5
LMArena Text: software and IT15381463Claude Opus 5.5
LMArena WebDev: React18551508Claude Opus 5.5
LMArena WebDev: HTML17531520Claude Opus 5.5
LMArena WebDev: from an image17531517Claude Opus 5.5
SciCode18.5%6.2%Claude Opus 5.5
Neither model has a result on the other 13 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Opus 5.5 and GPT-5.6 Luna
BenchmarkClaude Opus 5.5GPT-5.6 LunaLeader
AA Intelligence Index57.637.3Claude Opus 5.5
Epoch Capabilities Index168.8156.5Claude Opus 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index130
Agentic work benchmarks for Claude Opus 5.5 and GPT-5.6 Luna
BenchmarkClaude Opus 5.5GPT-5.6 LunaLeader
AA Agentic IndexNot measured42.1Only GPT-5.6 Luna measured
Design Arena: agents building web apps1316Not measuredOnly Claude Opus 5.5 measured
Design Arena: agents building mobile apps1308Not measuredOnly Claude Opus 5.5 measured
Design Arena: spreadsheets1368Not measuredOnly Claude Opus 5.5 measured
LiveBench research85.0%51.0%Claude Opus 5.5
LiveBench browser80.0%68.0%Claude Opus 5.5
LiveBench long agentic85.0%30.4%Claude Opus 5.5
SREBench (Vals AI)33.6%1.5%Claude Opus 5.5
Finance Agent (Vals AI)58.6%55.0%Claude Opus 5.5
Tax Agent Bench (Vals AI)45.6%24.8%Claude Opus 5.5
Legal Research Bench (Vals AI)50.5%36.5%Claude Opus 5.5
Harvey's Legal Agent Benchmark (Vals AI)9.2%Not measuredOnly Claude Opus 5.5 measured
Excel Modeling Benchmark (Vals AI)75.9%67.1%Claude Opus 5.5
BioMysteryBench (Vals AI)79.3%61.5%Claude Opus 5.5
Terminal-Bench-Science (Vals AI)47.1%0.0%Claude Opus 5.5
Vals Science Index58.7%25.3%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%43.0%Claude Opus 5.5
Remote Labor Index21.3%Not measuredOnly Claude Opus 5.5 measured
BALROGNot measured45.6%Only GPT-5.6 Luna measured
SpireClimb3.3%Not measuredOnly Claude Opus 5.5 measured
Vending-Bench 2$9,235$4,095Claude Opus 5.5
LMArena Search1213Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 16 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index121
Reasoning benchmarks for Claude Opus 5.5 and GPT-5.6 Luna
BenchmarkClaude Opus 5.5GPT-5.6 LunaLeader
GPQA DiamondNot measured91.7%Only GPT-5.6 Luna measured
LiveBench reasoning92.2%85.6%Claude Opus 5.5
MysteryMechanism (Vals AI)49.5%14.4%Claude Opus 5.5
MMMU Pro (Vals AI)Not measured85.0%Only GPT-5.6 Luna measured
GPQA Diamond (Artificial Analysis run)Not measured91.1%Only GPT-5.6 Luna measured
Humanity's Last Exam (Artificial Analysis run)61.4%39.5%Claude Opus 5.5
GPQA Diamond (Epoch AI run)90.6%91.6%GPT-5.6 Luna
ARC-AGI98.5%88.0%Claude Opus 5.5
ARC-AGI-293.3%59.5%Claude Opus 5.5
SimpleBenchNot measured46.8%Only GPT-5.6 Luna measured
Chess puzzles67.0%43.0%Claude Opus 5.5
Mystery game puzzles71.0%21.0%Claude Opus 5.5
EBR-bench71.4%Not measuredOnly Claude Opus 5.5 measured
LMArena Text: hard prompts15361451Claude Opus 5.5
LMArena Text: expert15491478Claude Opus 5.5
LMArena Text: hard prompts in English15351460Claude Opus 5.5
LMArena Vision: diagrams13451273Claude Opus 5.5
LMArena Vision: homework13621282Claude Opus 5.5
Kagi LLM BenchmarkNot measured49.1%Only GPT-5.6 Luna measured
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Opus 5.5 and GPT-5.6 Luna
BenchmarkClaude Opus 5.5GPT-5.6 LunaLeader
OTIS Mock AIME100.0%98.3%Claude Opus 5.5
FrontierMath, tiers 1 to 391.2%82.1%Claude Opus 5.5
FrontierMath, tier 495.0%61.0%Claude Opus 5.5
ProofBench100.0%60.0%Claude Opus 5.5
LMArena Text: math15181459Claude Opus 5.5
LMArena Text: mathematical work15161470Claude 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-5.6 Luna
BenchmarkClaude Opus 5.5GPT-5.6 LunaLeader
MMLU ProNot measured86.0%Only GPT-5.6 Luna measured
LegalBench (Vals AI)Not measured84.0%Only GPT-5.6 Luna measured
CorpFin (Vals AI)Not measured64.2%Only GPT-5.6 Luna measured
TaxEval (Vals AI)Not measured76.2%Only GPT-5.6 Luna measured
MortgageTax (Vals AI)Not measured67.3%Only GPT-5.6 Luna measured
MedCode (Vals AI)49.8%42.4%Claude Opus 5.5
SimpleQA Verified72.2%41.0%Claude Opus 5.5
LMArena Text: science15241433Claude Opus 5.5
LMArena Text: medicine and healthcare15091399Claude Opus 5.5
LMArena Text: legal and government15181446Claude Opus 5.5
LMArena Text: business and finance14941439Claude Opus 5.5
FACTS Benchmark Suite65.3%35.0%Claude Opus 5.5
Neither model has a result on the other 6 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-5.6 Luna
BenchmarkClaude Opus 5.5GPT-5.6 LunaLeader
Design Arena: websites13351255Claude Opus 5.5
Design Arena: UI components13851248Claude Opus 5.5
Design Arena: game dev14611194Claude Opus 5.5
Design Arena: data viz13971211Claude Opus 5.5
Design Arena: 3D14761121Claude Opus 5.5
Design Arena: all code categories13901231Claude Opus 5.5
Design Arena: SVG13291194Claude Opus 5.5
Design Arena: ASCII artNot measured1142Only GPT-5.6 Luna measured
LiveBench design86.9%76.0%Claude Opus 5.5
GeneralLike-for-likePublic boards, shown as published, kept out of the index260
General benchmarks for Claude Opus 5.5 and GPT-5.6 Luna
BenchmarkClaude Opus 5.5GPT-5.6 LunaLeader
Vals Index70.2%Not measuredOnly Claude Opus 5.5 measured
LiveBench data analysis80.3%78.0%Claude Opus 5.5
Public Benefits Bench (Vals AI)70.6%61.2%Claude Opus 5.5
SAGE (Vals AI)45.8%44.2%Claude Opus 5.5
MedScribe (Vals AI)91.4%84.4%Claude Opus 5.5
Vals Multimodal IndexNot measured69.1%Only GPT-5.6 Luna measured
Long context reasoning (AA-LCR)84.7%83.7%Claude Opus 5.5
DTBench98.9%89.1%Claude Opus 5.5
LMCA68.2%48.5%Claude Opus 5.5
Surface Evolver BenchNot measured61.9%Only GPT-5.6 Luna measured
Furniture assembly83.3%42.5%Claude Opus 5.5
LMArena Text15161431Claude Opus 5.5
LMArena Text: instruction following15371437Claude Opus 5.5
LMArena Text: creative writing15351396Claude Opus 5.5
LMArena Vision13211257Claude Opus 5.5
LMArena Text: English15191441Claude Opus 5.5
LMArena Text: non-English15071417Claude Opus 5.5
LMArena Text: Chinese15821470Claude Opus 5.5
LMArena Text: GermanNot measured1455Only GPT-5.6 Luna measured
LMArena Text: Japanese15341415Claude Opus 5.5
LMArena Text: KoreanNot measured1415Only GPT-5.6 Luna measured
LMArena Text: French14931458Claude Opus 5.5
LMArena Text: Spanish15081446Claude Opus 5.5
LMArena Text: Russian15171427Claude Opus 5.5
LMArena Text: PolishNot measured1405Only GPT-5.6 Luna measured
LMArena Text: multi-turn15011434Claude Opus 5.5
LMArena Text: longer queries15321436Claude Opus 5.5
LMArena Text: writing and language15321419Claude Opus 5.5
LMArena Text: entertainment and media15151402Claude Opus 5.5
LMArena Vision: English13171263Claude Opus 5.5
LMArena Vision: ChineseNot measured1294Only GPT-5.6 Luna measured
LMArena Vision: reading text13261264Claude Opus 5.5
LMArena Vision: humorNot measured1190Only GPT-5.6 Luna measured
LMArena Vision: creative writing13201257Claude Opus 5.5
LMArena DocumentNot measured1457Only GPT-5.6 Luna measured
Neither model has a result on the other 11 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-5.6 Luna
BenchmarkClaude Opus 5.5GPT-5.6 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-5.6 Luna$0.0008Fits in one request

GPT-5.6 Luna costs less

Repository review

50K input + 3K output tokens

Claude Opus 5.5$0.260Fits in one request
GPT-5.6 Luna$0.014Fits in one request

GPT-5.6 Luna costs less

Agent loop

200K input + 10K output tokens

Claude Opus 5.5$1.00Fits in one request
GPT-5.6 Luna$0.052Fits in one request

GPT-5.6 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-5.6 Luna
SpecificationAnthropic Claude Opus 5.5OpenAI GPT-5.6 Luna
MakerAnthropicOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 22, 2026July 9, 2026
Context window1M1.05M
Input $/Mtok$4.00$0.20
Output $/Mtok$20.00$1.20
Coding index88.858.0
Independent measurements behind it56
Cost per solved taskNot computable$0.04
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 5.5 better than GPT-5.6 Luna for coding?

Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 58.0 for GPT-5.6 Luna, though on 5 benchmarks against 6. Pick GPT-5.6 Luna for output tokens 16.7x cheaper ($1.20 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).

Which is cheaper, Claude Opus 5.5 or GPT-5.6 Luna?

Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; GPT-5.6 Luna costs $0.20 and $1.20. Cost per solved task is known for GPT-5.6 Luna only.

Which has the bigger context window, Claude Opus 5.5 or GPT-5.6 Luna?

GPT-5.6 Luna, with 1.05M tokens against 1M.

How many benchmarks is the Claude Opus 5.5 vs GPT-5.6 Luna comparison based on?

94 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-5.6 Luna's on 6. Where only one model has a result, the page says so instead of naming a winner.

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