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Claude Sonnet 4.5 vs GPT-5.6 Luna

Updated October 21, 2026. 71 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Sonnet 4.5 Replace GPT-5.6 Luna
Claude Sonnet 4.5Anthropic
Coding
59.1
Overall
20.7
Output $/M
$15.00
29
GPT-5.6 LunaOpenAI
Coding
61.5
Overall
37.3
Output $/M
$1.20
42
vs boards won of 71 shared

Decision reading

Pick GPT-5.6 Luna for coding: it scores 61.5 on the Vibe Coding Index against 59.1 for Claude Sonnet 4.5.

Pick Claude Sonnet 4.5 when what matters is LMArena Text: coding or LMArena Text: software and IT, where it leads.

Model AClaude Sonnet 4.5Anthropic59.1/1002 independent benchmarks$1.16 per solved taskModel BGPT-5.6 LunaOpenAI61.5/1002 independent benchmarks$0.04 per solved task
Shared results
71
Claude Sonnet 4.5 only
21
GPT-5.6 Luna only
45
Like-for-like categories
8 of 9

Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.

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 Sonnet 4.5 59.1 from 2 benchmarks, GPT-5.6 Luna 61.5 from 2 benchmarks.
Widest category
Math, 30.2 points apart on average over 6 shared benchmarks.
Widest single gap
FrontierMath, tier 4: Claude Sonnet 4.5 2.4% against GPT-5.6 Luna 61.0%, 58.5 points apart on a 0 to 100 scale.
Output price
Claude Sonnet 4.5 $15.00 against GPT-5.6 Luna $1.20 per million output tokens, 12.5x apart.
Context window
Claude Sonnet 4.5 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 Sonnet 4.5BarsGPT-5.6 LunaTies
Coding27
Intelligence02
Agentic work02
Reasoning47
Math06
Knowledge74
Web design26
General148
All shared boards2942
CodingLike-for-likeFour of these boards feed the Vibe Coding Index27
Coding benchmarks for Claude Sonnet 4.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 4.5GPT-5.6 LunaLeader
SWE-bench Verified74.8%Not measuredOnly Claude Sonnet 4.5 measured
SWE-bench Multilingual67.0%Not measuredOnly Claude Sonnet 4.5 measured
LiveBench codingNot measured73.6%Only GPT-5.6 Luna measured
LMArena WebDev13941518GPT-5.6 Luna
AA Coding Index52.171.4GPT-5.6 Luna
LiveCodeBench (Vals AI)73.0%Not measuredOnly Claude Sonnet 4.5 measured
SWE-bench Verified (Vals AI)70.0%93.0%GPT-5.6 Luna
Terminal-Bench 4 (Vals AI)Not measured11.6%Only GPT-5.6 Luna measured
Vibe Code Bench (Vals AI)22.6%77.1%GPT-5.6 Luna
Code migration (Vals AI)Not measured44.5%Only GPT-5.6 Luna measured
ProgramBench (Vals AI)Not measured0.0%Only GPT-5.6 Luna measured
IOI (Vals AI)Not measured61.8%Only GPT-5.6 Luna measured
Terminal-Bench 2.1 (Vals AI)Not measured79.0%Only GPT-5.6 Luna measured
Vibe Code Bench 1-100 (Vals AI)Not measured22.6%Only GPT-5.6 Luna measured
SkillsBench (Vals AI)Not measured60.5%Only GPT-5.6 Luna measured
CyberBench (Vals AI)Not measured73.6%Only GPT-5.6 Luna measured
SciCodeNot measured53.6%Only GPT-5.6 Luna measured
Terminal-Bench46.5%Not measuredOnly Claude Sonnet 4.5 measured
FrontierCodeNot measured39.8%Only GPT-5.6 Luna measured
GSO-Bench14.7%Not measuredOnly Claude Sonnet 4.5 measured
WeirdML47.7%60.9%GPT-5.6 Luna
Cybench60.0%Not measuredOnly Claude Sonnet 4.5 measured
ALE-BenchNot measured1667.4Only GPT-5.6 Luna measured
LMArena Text: coding14881466Claude Sonnet 4.5
LMArena Text: software and IT14731463Claude Sonnet 4.5
LMArena WebDev: React13861508GPT-5.6 Luna
LMArena WebDev: HTML13991520GPT-5.6 Luna
LMArena WebDev: from an imageNot measured1517Only GPT-5.6 Luna measured
Neither model has a result on the other 10 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Claude Sonnet 4.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 4.5GPT-5.6 LunaLeader
AA Intelligence Index20.737.3GPT-5.6 Luna
Epoch Capabilities Index146.7156.5GPT-5.6 Luna
Agentic workLike-for-likePublic boards, shown as published, kept out of the index02
Agentic work benchmarks for Claude Sonnet 4.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 4.5GPT-5.6 LunaLeader
AA Agentic Index15.842.1GPT-5.6 Luna
Design Arena: agents building web apps1060Not measuredOnly Claude Sonnet 4.5 measured
Design Arena: agents building full-stack apps1050Not measuredOnly Claude Sonnet 4.5 measured
Design Arena: agents building mobile apps1137Not measuredOnly Claude Sonnet 4.5 measured
LiveBench researchNot measured51.0%Only GPT-5.6 Luna measured
LiveBench browserNot measured68.0%Only GPT-5.6 Luna measured
LiveBench long agenticNot measured30.4%Only GPT-5.6 Luna measured
SREBench (Vals AI)Not measured1.5%Only GPT-5.6 Luna measured
Finance Agent (Vals AI)Not measured55.0%Only GPT-5.6 Luna measured
Tax Agent Bench (Vals AI)Not measured24.8%Only GPT-5.6 Luna measured
Legal Research Bench (Vals AI)Not measured36.5%Only GPT-5.6 Luna measured
Excel Modeling Benchmark (Vals AI)Not measured67.1%Only GPT-5.6 Luna measured
BioMysteryBench (Vals AI)Not measured61.5%Only GPT-5.6 Luna measured
Terminal-Bench-Science (Vals AI)Not measured0.0%Only GPT-5.6 Luna measured
Vals Science IndexNot measured25.3%Only GPT-5.6 Luna measured
APEX-AgentsNot measured43.0%Only GPT-5.6 Luna measured
METR time horizons67.4%Not measuredOnly Claude Sonnet 4.5 measured
Remote Labor Index2.1%Not measuredOnly Claude Sonnet 4.5 measured
GDPval42.5%Not measuredOnly Claude Sonnet 4.5 measured
BALROGNot measured45.6%Only GPT-5.6 Luna measured
DeepResearch Bench52.6%Not measuredOnly Claude Sonnet 4.5 measured
OSWorld62.9%Not measuredOnly Claude Sonnet 4.5 measured
Vending-Bench 2$3,839$4,095GPT-5.6 Luna
Neither model has a result on the other 16 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index47
Reasoning benchmarks for Claude Sonnet 4.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 4.5GPT-5.6 LunaLeader
GPQA Diamond81.6%91.7%GPT-5.6 Luna
LiveBench reasoningNot measured85.6%Only GPT-5.6 Luna measured
MysteryMechanism (Vals AI)Not measured14.4%Only GPT-5.6 Luna measured
MMMU Pro (Vals AI)79.3%85.0%GPT-5.6 Luna
GPQA Diamond (Artificial Analysis run)Not measured91.1%Only GPT-5.6 Luna measured
Humanity's Last Exam (Artificial Analysis run)Not measured39.5%Only GPT-5.6 Luna measured
GPQA Diamond (Epoch AI run)82.3%91.6%GPT-5.6 Luna
ARC-AGI63.7%88.0%GPT-5.6 Luna
ARC-AGI-213.6%59.5%GPT-5.6 Luna
SimpleBench54.3%46.8%Claude Sonnet 4.5
Chess puzzles10.0%43.0%GPT-5.6 Luna
Mystery game puzzles17.0%21.0%GPT-5.6 Luna
EBR-bench2.4%Not measuredOnly Claude Sonnet 4.5 measured
VPCT39.8%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: hard prompts14621451Claude Sonnet 4.5
LMArena Text: expert14831478Claude Sonnet 4.5
LMArena Text: hard prompts in English14711460Claude Sonnet 4.5
LMArena Vision: diagramsNot measured1273Only GPT-5.6 Luna measured
LMArena Vision: homeworkNot measured1282Only GPT-5.6 Luna measured
Neither model has a result on the other 2 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index06
Math benchmarks for Claude Sonnet 4.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 4.5GPT-5.6 LunaLeader
AIME88.2%Not measuredOnly Claude Sonnet 4.5 measured
MGSM (Vals AI)94.3%Not measuredOnly Claude Sonnet 4.5 measured
OTIS Mock AIME77.8%98.3%GPT-5.6 Luna
FrontierMath, tiers 1 to 323.9%82.1%GPT-5.6 Luna
FrontierMath, tier 42.4%61.0%GPT-5.6 Luna
ProofBench19.0%60.0%GPT-5.6 Luna
MATH level 597.7%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: math14491459GPT-5.6 Luna
LMArena Text: mathematical work14621470GPT-5.6 Luna
Neither model has a result on the other 4 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index74
Knowledge benchmarks for Claude Sonnet 4.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 4.5GPT-5.6 LunaLeader
MMLU Pro87.4%86.0%Claude Sonnet 4.5
LegalBench (Vals AI)84.1%84.0%Claude Sonnet 4.5
CaseLaw (Vals AI)62.2%Not measuredOnly Claude Sonnet 4.5 measured
CorpFin (Vals AI)62.0%64.2%GPT-5.6 Luna
TaxEval (Vals AI)73.3%76.2%GPT-5.6 Luna
MortgageTax (Vals AI)64.0%67.3%GPT-5.6 Luna
MedQA (Vals AI)94.7%Not measuredOnly Claude Sonnet 4.5 measured
MedCode (Vals AI)44.1%42.4%Claude Sonnet 4.5
SimpleQA Verified30.7%41.0%GPT-5.6 Luna
LMArena Text: science14481433Claude Sonnet 4.5
LMArena Text: medicine and healthcare14441399Claude Sonnet 4.5
LMArena Text: legal and government14511446Claude Sonnet 4.5
LMArena Text: business and finance14401439Claude Sonnet 4.5
Neither model has a result on the other 4 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index26
Web design benchmarks for Claude Sonnet 4.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 4.5GPT-5.6 LunaLeader
Design Arena: websites11901256GPT-5.6 Luna
Design Arena: UI components11731250GPT-5.6 Luna
Design Arena: game dev11661196GPT-5.6 Luna
Design Arena: data viz11671212GPT-5.6 Luna
Design Arena: 3D11581121Claude Sonnet 4.5
Design Arena: all code categories11831231GPT-5.6 Luna
Design Arena: SVG11141193GPT-5.6 Luna
Design Arena: ASCII art12041144Claude Sonnet 4.5
LiveBench designNot measured76.0%Only GPT-5.6 Luna measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index148
General benchmarks for Claude Sonnet 4.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 4.5GPT-5.6 LunaLeader
LiveBench data analysisNot measured78.0%Only GPT-5.6 Luna measured
Public Benefits Bench (Vals AI)Not measured61.2%Only GPT-5.6 Luna measured
SAGE (Vals AI)36.1%44.2%GPT-5.6 Luna
MedScribe (Vals AI)84.5%84.4%Claude Sonnet 4.5
Vals Multimodal IndexNot measured69.1%Only GPT-5.6 Luna measured
Long context reasoning (AA-LCR)Not measured83.7%Only GPT-5.6 Luna measured
DTBench83.2%89.1%GPT-5.6 Luna
LMCA38.8%48.5%GPT-5.6 Luna
Surface Evolver BenchNot measured61.9%Only GPT-5.6 Luna measured
Furniture assemblyNot measured42.5%Only GPT-5.6 Luna measured
LMArena Text14381431Claude Sonnet 4.5
LMArena Text: instruction following14591437Claude Sonnet 4.5
LMArena Text: creative writing14421396Claude Sonnet 4.5
LMArena VisionNot measured1257Only GPT-5.6 Luna measured
LMArena Text: English14501441Claude Sonnet 4.5
LMArena Text: non-English14251417Claude Sonnet 4.5
LMArena Text: Chinese14601470GPT-5.6 Luna
LMArena Text: German14271455GPT-5.6 Luna
LMArena Text: Japanese13901415GPT-5.6 Luna
LMArena Text: Korean14021415GPT-5.6 Luna
LMArena Text: French14591458Claude Sonnet 4.5
LMArena Text: Spanish14581446Claude Sonnet 4.5
LMArena Text: Russian14371427Claude Sonnet 4.5
LMArena Text: Polish14231405Claude Sonnet 4.5
LMArena Text: multi-turn14651434Claude Sonnet 4.5
LMArena Text: longer queries14751436Claude Sonnet 4.5
LMArena Text: writing and language14421419Claude Sonnet 4.5
LMArena Text: entertainment and media14281402Claude Sonnet 4.5
LMArena Vision: EnglishNot measured1263Only GPT-5.6 Luna measured
LMArena Vision: ChineseNot measured1294Only GPT-5.6 Luna measured
LMArena Vision: reading textNot measured1264Only GPT-5.6 Luna measured
LMArena Vision: humorNot measured1190Only GPT-5.6 Luna measured
LMArena Vision: creative writingNot measured1257Only GPT-5.6 Luna measured
LMArena Document14501457GPT-5.6 Luna
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 Sonnet 4.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 4.5GPT-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 Sonnet 4.5$0.011Fits 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 Sonnet 4.5$0.195Fits 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 Sonnet 4.5$0.750Fits 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 Sonnet 4.5 and GPT-5.6 Luna
SpecificationAnthropic Claude Sonnet 4.5OpenAI GPT-5.6 Luna
MakerAnthropicOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 29, 2025July 9, 2026
Context window1M1.05M
Input $/Mtok$3.00$0.20
Output $/Mtok$15.00$1.20
Coding index59.161.5
Independent measurements behind it22
Cost per solved task$1.16$0.04
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Sonnet 4.5 better than GPT-5.6 Luna for coding?

Pick GPT-5.6 Luna for coding: it scores 61.5 on the Vibe Coding Index against 59.1 for Claude Sonnet 4.5. Pick Claude Sonnet 4.5 when what matters is LMArena Text: coding or LMArena Text: software and IT, where it leads.

Which is cheaper, Claude Sonnet 4.5 or GPT-5.6 Luna?

Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; GPT-5.6 Luna costs $0.20 and $1.20. Per solved SWE-bench Verified task, Claude Sonnet 4.5 costs $1.16 and GPT-5.6 Luna $0.04.

Which has the bigger context window, Claude Sonnet 4.5 or GPT-5.6 Luna?

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

How many benchmarks is the Claude Sonnet 4.5 vs GPT-5.6 Luna comparison based on?

71 benchmarks have a result for both models as of October 21, 2026. Claude Sonnet 4.5's coding index rests on 2 independent benchmarks and GPT-5.6 Luna's on 2. Where only one model has a result, the page says so instead of naming a winner.

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