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Claude Opus 4.8 vs GPT-5.6 Luna

Claude Opus 4.8 leads GPT-5.6 Luna on coding, 65.0 to 58.0 on the Vibe Coding Index, and GPT-5.6 Luna costs 20.8x less per output token ($1.20 vs $25.00 per million). Updated October 22, 2026; 110 benchmarks have a result for both.

Replace Claude Opus 4.8 Replace GPT-5.6 Luna
Claude Opus 4.8Anthropic
Coding
65.0
Overall
69.8
Output $/M
$25.00
96
GPT-5.6 LunaOpenAI
Coding
58.0
Overall
61.6
Output $/M
$1.20
12
vs boards won of 110 shared, 2 tied

Claude Opus 4.8 or GPT-5.6 Luna: which to pick

Pick Claude Opus 4.8 for coding: it scores 65.0 on the Vibe Coding Index against 58.0 for GPT-5.6 Luna.

Pick GPT-5.6 Luna for output tokens 20.8x cheaper ($1.20 vs $25.00 per million) and a lower cost per solved task ($0.04 against $2.17).

Model AClaude Opus 4.8Anthropic65.0/1006 independent benchmarks$2.17 per solved taskModel BGPT-5.6 LunaOpenAI58.0/1006 independent benchmarks$0.04 per solved task
Shared results
110
Claude Opus 4.8 only
26
GPT-5.6 Luna only
10
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 4.8 65.0 from 6 benchmarks, GPT-5.6 Luna 58.0 from 6 benchmarks.
Widest category
Agentic work, 10.3 points apart on average over 11 shared benchmarks.
Widest single gap
Kagi LLM Benchmark: Claude Opus 4.8 88.8% against GPT-5.6 Luna 49.1%, 39.7 points apart on a 0 to 100 scale.
Output price
Claude Opus 4.8 $25.00 against GPT-5.6 Luna $1.20 per million output tokens, 20.8x apart.
Context window
Claude Opus 4.8 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 4.8BarsGPT-5.6 LunaTies
Coding153
Intelligence20
Agentic work92
Reasoning161
Math321 tie
Knowledge102
Web design90
General3221 tie
All shared boards96122 ties
CodingLike-for-likeSix of these boards feed the Vibe Coding Index153
Coding benchmarks for Claude Opus 4.8 and GPT-5.6 Luna
BenchmarkClaude Opus 4.8GPT-5.6 LunaLeader
LiveBench coding77.3%73.6%Claude Opus 4.8
LMArena WebDev15561518Claude Opus 4.8
AA Coding Index74.371.4Claude Opus 4.8
LiveCodeBench (Vals AI)87.8%Not measuredOnly Claude Opus 4.8 measured
SWE-bench Verified (Vals AI)88.6%93.0%GPT-5.6 Luna
Terminal-Bench 4 (Vals AI)23.2%11.6%Claude Opus 4.8
Vibe Code Bench (Vals AI)82.7%77.1%Claude Opus 4.8
Code migration (Vals AI)47.3%44.5%Claude Opus 4.8
ProgramBench (Vals AI)1.0%0.0%Claude Opus 4.8
IOI (Vals AI)Not measured61.8%Only GPT-5.6 Luna measured
Terminal-Bench 2.1 (Vals AI)71.9%79.0%GPT-5.6 Luna
Vibe Code Bench 1-100 (Vals AI)Not measured22.6%Only GPT-5.6 Luna measured
SkillsBench (Vals AI)59.2%60.5%GPT-5.6 Luna
CyberBench (Vals AI)Not measured73.6%Only GPT-5.6 Luna measured
SciCode54.4%53.6%Claude Opus 4.8
Terminal-Bench Hard (Artificial Analysis run)58.3%Not measuredOnly Claude Opus 4.8 measured
FrontierCode46.5%39.8%Claude Opus 4.8
GSO-Bench47.1%Not measuredOnly Claude Opus 4.8 measured
WeirdML82.9%60.9%Claude Opus 4.8
ALE-BenchNot measured1667.4Only GPT-5.6 Luna measured
LMArena Text: coding14901466Claude Opus 4.8
LMArena Text: software and IT14881463Claude Opus 4.8
LMArena WebDev: React15571508Claude Opus 4.8
LMArena WebDev: HTML15431520Claude Opus 4.8
LMArena WebDev: from an imageNot measured1517Only GPT-5.6 Luna measured
SciCode12.3%6.2%Claude Opus 4.8
SWE Atlas: Codebase QnA57.3%Not measuredOnly Claude Opus 4.8 measured
SWE Atlas: Refactoring46.7%Not measuredOnly Claude Opus 4.8 measured
SWE Atlas: Test Writing49.6%Not measuredOnly Claude Opus 4.8 measured
Neither model has a result on the other 14 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Opus 4.8 and GPT-5.6 Luna
BenchmarkClaude Opus 4.8GPT-5.6 LunaLeader
AA Intelligence Index41.837.3Claude Opus 4.8
Epoch Capabilities Index159.0156.5Claude Opus 4.8
Agentic workLike-for-likePublic boards, shown as published, kept out of the index92
Agentic work benchmarks for Claude Opus 4.8 and GPT-5.6 Luna
BenchmarkClaude Opus 4.8GPT-5.6 LunaLeader
AA Agentic Index41.942.1GPT-5.6 Luna
Design Arena: agents building web apps1233Not measuredOnly Claude Opus 4.8 measured
Design Arena: agents building full-stack apps1249Not measuredOnly Claude Opus 4.8 measured
Design Arena: agents building mobile apps1222Not measuredOnly Claude Opus 4.8 measured
Design Arena: agents building Android apps1231Not measuredOnly Claude Opus 4.8 measured
Design Arena: agents building Godot games1231Not measuredOnly Claude Opus 4.8 measured
Design Arena: agents building games1238Not measuredOnly Claude Opus 4.8 measured
Design Arena: HTML slides1160Not measuredOnly Claude Opus 4.8 measured
Design Arena: PowerPoint slides1201Not measuredOnly Claude Opus 4.8 measured
Design Arena: spreadsheets1314Not measuredOnly Claude Opus 4.8 measured
LiveBench research81.8%51.0%Claude Opus 4.8
LiveBench browser96.0%68.0%Claude Opus 4.8
LiveBench long agentic48.3%30.4%Claude Opus 4.8
SREBench (Vals AI)Not measured1.5%Only GPT-5.6 Luna measured
Finance Agent (Vals AI)53.9%55.0%GPT-5.6 Luna
Tax Agent Bench (Vals AI)30.0%24.8%Claude Opus 4.8
Legal Research Bench (Vals AI)43.8%36.5%Claude Opus 4.8
Excel Modeling Benchmark (Vals AI)69.4%67.1%Claude Opus 4.8
BioMysteryBench (Vals AI)Not measured61.5%Only GPT-5.6 Luna measured
Terminal-Bench-Science (Vals AI)4.3%0.0%Claude Opus 4.8
Vals Science IndexNot measured25.3%Only GPT-5.6 Luna measured
Time Horizon Index (Vals AI)11.8%Not measuredOnly Claude Opus 4.8 measured
τ²-Bench Telecom94.4%Not measuredOnly Claude Opus 4.8 measured
APEX-Agents48.9%43.0%Claude Opus 4.8
Remote Labor Index8.3%Not measuredOnly Claude Opus 4.8 measured
OSWorld 2.020.6%Not measuredOnly Claude Opus 4.8 measured
BALROGNot measured45.6%Only GPT-5.6 Luna measured
DeepResearch Bench50.2%Not measuredOnly Claude Opus 4.8 measured
PostTrainBench33.8%Not measuredOnly Claude Opus 4.8 measured
Vending-Bench 2$5,787$4,095Claude Opus 4.8
LMArena Search1204Not measuredOnly Claude Opus 4.8 measured
MCP Atlas82.2%Not measuredOnly Claude Opus 4.8 measured
Neither model has a result on the other 10 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index161
Reasoning benchmarks for Claude Opus 4.8 and GPT-5.6 Luna
BenchmarkClaude Opus 4.8GPT-5.6 LunaLeader
GPQA Diamond92.4%91.7%Claude Opus 4.8
LiveBench reasoning89.2%85.6%Claude Opus 4.8
MysteryMechanism (Vals AI)Not measured14.4%Only GPT-5.6 Luna measured
MMMU Pro (Vals AI)86.6%85.0%Claude Opus 4.8
GPQA Diamond (Artificial Analysis run)92.0%91.1%Claude Opus 4.8
Humanity's Last Exam (Artificial Analysis run)48.7%39.5%Claude Opus 4.8
GPQA Diamond (Epoch AI run)91.0%91.6%GPT-5.6 Luna
ARC-AGI92.5%88.0%Claude Opus 4.8
ARC-AGI-272.1%59.5%Claude Opus 4.8
SimpleBench64.8%46.8%Claude Opus 4.8
Chess puzzles52.0%43.0%Claude Opus 4.8
Mystery game puzzles36.0%21.0%Claude Opus 4.8
EBR-bench28.6%Not measuredOnly Claude Opus 4.8 measured
LMArena Text: hard prompts14821451Claude Opus 4.8
LMArena Text: expert15031478Claude Opus 4.8
LMArena Text: hard prompts in English14871460Claude Opus 4.8
LMArena Vision: diagrams13151273Claude Opus 4.8
LMArena Vision: homework13371282Claude Opus 4.8
Kagi LLM Benchmark88.8%49.1%Claude Opus 4.8
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index32
Math benchmarks for Claude Opus 4.8 and GPT-5.6 Luna
BenchmarkClaude Opus 4.8GPT-5.6 LunaLeader
OTIS Mock AIME98.3%98.3%Tie
FrontierMath, tiers 1 to 380.0%82.1%GPT-5.6 Luna
FrontierMath, tier 456.1%61.0%GPT-5.6 Luna
ProofBench69.0%60.0%Claude Opus 4.8
LMArena Text: math14861459Claude Opus 4.8
LMArena Text: mathematical work14971470Claude Opus 4.8
MathArena39.8%Not measuredOnly Claude Opus 4.8 measured
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index102
Knowledge benchmarks for Claude Opus 4.8 and GPT-5.6 Luna
BenchmarkClaude Opus 4.8GPT-5.6 LunaLeader
MMLU Pro89.6%86.0%Claude Opus 4.8
LegalBench (Vals AI)83.6%84.0%GPT-5.6 Luna
CorpFin (Vals AI)66.7%64.2%Claude Opus 4.8
TaxEval (Vals AI)75.6%76.2%GPT-5.6 Luna
MortgageTax (Vals AI)69.9%67.3%Claude Opus 4.8
MedCode (Vals AI)53.2%42.4%Claude Opus 4.8
SimpleQA Verified53.0%41.0%Claude Opus 4.8
LMArena Text: science14771433Claude Opus 4.8
LMArena Text: medicine and healthcare14641399Claude Opus 4.8
LMArena Text: legal and government14771446Claude Opus 4.8
LMArena Text: business and finance14581439Claude Opus 4.8
FACTS Benchmark Suite53.5%35.0%Claude Opus 4.8
Neither model has a result on the other 8 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index90
Web design benchmarks for Claude Opus 4.8 and GPT-5.6 Luna
BenchmarkClaude Opus 4.8GPT-5.6 LunaLeader
Design Arena: websites12581255Claude Opus 4.8
Design Arena: UI components12551248Claude Opus 4.8
Design Arena: game dev12641195Claude Opus 4.8
Design Arena: data viz12401212Claude Opus 4.8
Design Arena: 3D12221121Claude Opus 4.8
Design Arena: all code categories12551230Claude Opus 4.8
Design Arena: SVG11941193Claude Opus 4.8
Design Arena: ASCII art12771142Claude Opus 4.8
LiveBench design78.8%76.0%Claude Opus 4.8
GeneralLike-for-likePublic boards, shown as published, kept out of the index322
General benchmarks for Claude Opus 4.8 and GPT-5.6 Luna
BenchmarkClaude Opus 4.8GPT-5.6 LunaLeader
LiveBench data analysis66.0%78.0%GPT-5.6 Luna
Public Benefits Bench (Vals AI)68.1%61.2%Claude Opus 4.8
SAGE (Vals AI)54.8%44.2%Claude Opus 4.8
MedScribe (Vals AI)85.8%84.4%Claude Opus 4.8
Vals Multimodal Index70.9%69.1%Claude Opus 4.8
IFBench62.2%Not measuredOnly Claude Opus 4.8 measured
Long context reasoning (AA-LCR)77.7%83.7%GPT-5.6 Luna
DTBench94.9%89.1%Claude Opus 4.8
LMCA57.5%48.5%Claude Opus 4.8
Surface Evolver Bench87.5%61.9%Claude Opus 4.8
Furniture assembly42.5%42.5%Tie
LMArena Text14611431Claude Opus 4.8
LMArena Text: instruction following14761437Claude Opus 4.8
LMArena Text: creative writing14541396Claude Opus 4.8
LMArena Vision12941257Claude Opus 4.8
LMArena Text: English14681441Claude Opus 4.8
LMArena Text: non-English14501417Claude Opus 4.8
LMArena Text: Chinese15061470Claude Opus 4.8
LMArena Text: German14721455Claude Opus 4.8
LMArena Text: Japanese14421415Claude Opus 4.8
LMArena Text: Korean14311415Claude Opus 4.8
LMArena Text: French14811458Claude Opus 4.8
LMArena Text: Spanish14651446Claude Opus 4.8
LMArena Text: Russian14741427Claude Opus 4.8
LMArena Text: Polish14591405Claude Opus 4.8
LMArena Text: multi-turn14761434Claude Opus 4.8
LMArena Text: longer queries14831436Claude Opus 4.8
LMArena Text: writing and language14611419Claude Opus 4.8
LMArena Text: entertainment and media14401402Claude Opus 4.8
LMArena Vision: English12931263Claude Opus 4.8
LMArena Vision: Chinese13461294Claude Opus 4.8
LMArena Vision: reading text13031264Claude Opus 4.8
LMArena Vision: humor12821190Claude Opus 4.8
LMArena Vision: creative writing13011257Claude Opus 4.8
LMArena Document14751457Claude Opus 4.8
EQ-Bench 412811156Claude Opus 4.8
Neither model has a result on the other 12 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Opus 4.8 and GPT-5.6 Luna
BenchmarkClaude Opus 4.8GPT-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 4.8$0.018Fits 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 4.8$0.325Fits 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 4.8$1.25Fits 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 4.8 and GPT-5.6 Luna
SpecificationAnthropic Claude Opus 4.8OpenAI GPT-5.6 Luna
MakerAnthropicOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedMay 27, 2026July 9, 2026
Context window1M1.05M
Input $/Mtok$5.00$0.20
Output $/Mtok$25.00$1.20
Coding index65.058.0
Independent measurements behind it66
Cost per solved task$2.17$0.04
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 4.8 better than GPT-5.6 Luna for coding?

Pick Claude Opus 4.8 for coding: it scores 65.0 on the Vibe Coding Index against 58.0 for GPT-5.6 Luna. Pick GPT-5.6 Luna for output tokens 20.8x cheaper ($1.20 vs $25.00 per million) and a lower cost per solved task ($0.04 against $2.17).

Which is cheaper, Claude Opus 4.8 or GPT-5.6 Luna?

Claude Opus 4.8 costs $5.00 per million input tokens and $25.00 per million output tokens; GPT-5.6 Luna costs $0.20 and $1.20. Per solved SWE-bench Verified task, Claude Opus 4.8 costs $2.17 and GPT-5.6 Luna $0.04.

Which has the bigger context window, Claude Opus 4.8 or GPT-5.6 Luna?

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

How many benchmarks is the Claude Opus 4.8 vs GPT-5.6 Luna comparison based on?

110 benchmarks have a result for both models as of October 22, 2026. Claude Opus 4.8's coding index rests on 6 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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