Enter opens the highlighted result. Esc closes.

Claude Sonnet 5.5 vs GPT-5.6 Luna

Claude Sonnet 5.5 leads GPT-5.6 Luna on coding, 87.3 to 58.0 on the Vibe Coding Index, and GPT-5.6 Luna costs 8.3x less per output token ($1.20 vs $10.00 per million). Updated October 22, 2026; 88 benchmarks have a result for both.

Replace Claude Sonnet 5.5 Replace GPT-5.6 Luna
Claude Sonnet 5.5Anthropic
Coding
87.3
Overall
82.8
Output $/M
$10.00
84
GPT-5.6 LunaOpenAI
Coding
58.0
Overall
61.6
Output $/M
$1.20
4
vs boards won of 88 shared

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

Pick Claude Sonnet 5.5 for coding: it scores 87.3 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 8.3x cheaper ($1.20 vs $10.00 per million) and a larger context window (1.05M against 1M tokens).

Model AClaude Sonnet 5.5Anthropic87.3/1005 independent benchmarksNo cost per solved taskModel BGPT-5.6 LunaOpenAI58.0/1006 independent benchmarks$0.04 per solved task
Shared results
88
Claude Sonnet 5.5 only
8
GPT-5.6 Luna only
31
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 Sonnet 5.5 87.3 from 5 benchmarks, GPT-5.6 Luna 58.0 from 6 benchmarks.
Widest category
Agentic work, 26.4 points apart on average over 13 shared benchmarks.
Widest single gap
Terminal-Bench 4 (Vals AI): Claude Sonnet 5.5 64.1% against GPT-5.6 Luna 11.6%, 70.0 points apart on a 0 to 100 scale.
Output price
Claude Sonnet 5.5 $10.00 against GPT-5.6 Luna $1.20 per million output tokens, 8.3x apart.
Context window
Claude Sonnet 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 Sonnet 5.5BarsGPT-5.6 LunaTies
Coding171
Intelligence20
Agentic work130
Reasoning110
Math60
Knowledge60
Web design70
General223
All shared boards844
CodingLike-for-likeSix of these boards feed the Vibe Coding Index171
Coding benchmarks for Claude Sonnet 5.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 5.5GPT-5.6 LunaLeader
LiveBench coding94.7%73.6%Claude Sonnet 5.5
LMArena WebDev17681518Claude Sonnet 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)64.1%11.6%Claude Sonnet 5.5
Vibe Code Bench (Vals AI)92.4%77.1%Claude Sonnet 5.5
Code migration (Vals AI)69.8%44.5%Claude Sonnet 5.5
ProgramBench (Vals AI)6.5%0.0%Claude Sonnet 5.5
IOI (Vals AI)83.1%61.8%Claude Sonnet 5.5
Terminal-Bench 2.1 (Vals AI)83.2%79.0%Claude Sonnet 5.5
SWE-bench Multimodal (Vals AI)58.3%Not measuredOnly Claude Sonnet 5.5 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)59.6%73.6%GPT-5.6 Luna
SciCode61.0%53.6%Claude Sonnet 5.5
FrontierCode52.1%39.8%Claude Sonnet 5.5
FrontierSWE61.9%Not measuredOnly Claude Sonnet 5.5 measured
WeirdMLNot measured60.9%Only GPT-5.6 Luna measured
ALE-Bench1819.11667.4Claude Sonnet 5.5
LMArena Text: coding15131466Claude Sonnet 5.5
LMArena Text: software and IT15041463Claude Sonnet 5.5
LMArena WebDev: React18171508Claude Sonnet 5.5
LMArena WebDev: HTML17411520Claude Sonnet 5.5
LMArena WebDev: from an image17371517Claude Sonnet 5.5
SciCode13.8%6.2%Claude Sonnet 5.5
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 Sonnet 5.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 5.5GPT-5.6 LunaLeader
AA Intelligence Index56.037.3Claude Sonnet 5.5
Epoch Capabilities Index166.2156.5Claude Sonnet 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index130
Agentic work benchmarks for Claude Sonnet 5.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 5.5GPT-5.6 LunaLeader
AA Agentic IndexNot measured42.1Only GPT-5.6 Luna measured
Design Arena: agents building web apps1305Not measuredOnly Claude Sonnet 5.5 measured
Design Arena: agents building mobile apps1260Not measuredOnly Claude Sonnet 5.5 measured
Design Arena: spreadsheets1260Not measuredOnly Claude Sonnet 5.5 measured
LiveBench research83.6%51.0%Claude Sonnet 5.5
LiveBench browser84.0%68.0%Claude Sonnet 5.5
LiveBench long agentic78.8%30.4%Claude Sonnet 5.5
SREBench (Vals AI)30.1%1.5%Claude Sonnet 5.5
Finance Agent (Vals AI)58.1%55.0%Claude Sonnet 5.5
Tax Agent Bench (Vals AI)42.0%24.8%Claude Sonnet 5.5
Legal Research Bench (Vals AI)48.1%36.5%Claude Sonnet 5.5
Harvey's Legal Agent Benchmark (Vals AI)10.4%Not measuredOnly Claude Sonnet 5.5 measured
Excel Modeling Benchmark (Vals AI)75.7%67.1%Claude Sonnet 5.5
BioMysteryBench (Vals AI)81.1%61.5%Claude Sonnet 5.5
Terminal-Bench-Science (Vals AI)47.1%0.0%Claude Sonnet 5.5
Vals Science Index59.1%25.3%Claude Sonnet 5.5
APEX-Agents75.5%43.0%Claude Sonnet 5.5
BALROGNot measured45.6%Only GPT-5.6 Luna measured
SpireClimb1.3%Not measuredOnly Claude Sonnet 5.5 measured
Vending-Bench 2$11,165$4,095Claude Sonnet 5.5
Neither model has a result on the other 21 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index110
Reasoning benchmarks for Claude Sonnet 5.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 5.5GPT-5.6 LunaLeader
GPQA DiamondNot measured91.7%Only GPT-5.6 Luna measured
LiveBench reasoning91.6%85.6%Claude Sonnet 5.5
MysteryMechanism (Vals AI)49.1%14.4%Claude Sonnet 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)55.0%39.5%Claude Sonnet 5.5
GPQA Diamond (Epoch AI run)95.6%91.6%Claude Sonnet 5.5
ARC-AGINot measured88.0%Only GPT-5.6 Luna measured
ARC-AGI-2Not measured59.5%Only GPT-5.6 Luna measured
SimpleBenchNot measured46.8%Only GPT-5.6 Luna measured
Chess puzzles59.0%43.0%Claude Sonnet 5.5
Mystery game puzzles65.0%21.0%Claude Sonnet 5.5
LMArena Text: hard prompts14941451Claude Sonnet 5.5
LMArena Text: expert15311478Claude Sonnet 5.5
LMArena Text: hard prompts in English15021460Claude Sonnet 5.5
LMArena Vision: diagrams13291273Claude Sonnet 5.5
LMArena Vision: homework13311282Claude Sonnet 5.5
Kagi LLM BenchmarkNot measured49.1%Only GPT-5.6 Luna measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Sonnet 5.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 5.5GPT-5.6 LunaLeader
OTIS Mock AIME100.0%98.3%Claude Sonnet 5.5
FrontierMath, tiers 1 to 388.8%82.1%Claude Sonnet 5.5
FrontierMath, tier 480.5%61.0%Claude Sonnet 5.5
ProofBench100.0%60.0%Claude Sonnet 5.5
LMArena Text: math14971459Claude Sonnet 5.5
LMArena Text: mathematical work15101470Claude Sonnet 5.5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index60
Knowledge benchmarks for Claude Sonnet 5.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 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)52.9%42.4%Claude Sonnet 5.5
SimpleQA Verified46.5%41.0%Claude Sonnet 5.5
LMArena Text: science14831433Claude Sonnet 5.5
LMArena Text: medicine and healthcare14641399Claude Sonnet 5.5
LMArena Text: legal and government14831446Claude Sonnet 5.5
LMArena Text: business and finance14681439Claude Sonnet 5.5
FACTS Benchmark SuiteNot measured35.0%Only GPT-5.6 Luna measured
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index70
Web design benchmarks for Claude Sonnet 5.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 5.5GPT-5.6 LunaLeader
Design Arena: websites13261255Claude Sonnet 5.5
Design Arena: UI components13681248Claude Sonnet 5.5
Design Arena: game dev14711194Claude Sonnet 5.5
Design Arena: data viz13921211Claude Sonnet 5.5
Design Arena: 3D14451121Claude Sonnet 5.5
Design Arena: all code categories13641231Claude Sonnet 5.5
Design Arena: SVGNot measured1194Only GPT-5.6 Luna measured
Design Arena: ASCII artNot measured1142Only GPT-5.6 Luna measured
LiveBench design85.0%76.0%Claude Sonnet 5.5
GeneralLike-for-likePublic boards, shown as published, kept out of the index223
General benchmarks for Claude Sonnet 5.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 5.5GPT-5.6 LunaLeader
Vals Index70.8%Not measuredOnly Claude Sonnet 5.5 measured
LiveBench data analysis59.5%78.0%GPT-5.6 Luna
Public Benefits Bench (Vals AI)67.2%61.2%Claude Sonnet 5.5
SAGE (Vals AI)51.8%44.2%Claude Sonnet 5.5
MedScribe (Vals AI)91.1%84.4%Claude Sonnet 5.5
Vals Multimodal IndexNot measured69.1%Only GPT-5.6 Luna measured
Long context reasoning (AA-LCR)82.7%83.7%GPT-5.6 Luna
DTBench97.3%89.1%Claude Sonnet 5.5
LMCA68.3%48.5%Claude Sonnet 5.5
Surface Evolver BenchNot measured61.9%Only GPT-5.6 Luna measured
Furniture assembly75.0%42.5%Claude Sonnet 5.5
LMArena Text14731431Claude Sonnet 5.5
LMArena Text: instruction following14921437Claude Sonnet 5.5
LMArena Text: creative writing14671396Claude Sonnet 5.5
LMArena Vision12871257Claude Sonnet 5.5
LMArena Text: English14841441Claude Sonnet 5.5
LMArena Text: non-English14561417Claude Sonnet 5.5
LMArena Text: Chinese15351470Claude Sonnet 5.5
LMArena Text: GermanNot measured1455Only GPT-5.6 Luna measured
LMArena Text: JapaneseNot measured1415Only GPT-5.6 Luna measured
LMArena Text: KoreanNot measured1415Only GPT-5.6 Luna measured
LMArena Text: French14991458Claude Sonnet 5.5
LMArena Text: Spanish14511446Claude Sonnet 5.5
LMArena Text: Russian14541427Claude Sonnet 5.5
LMArena Text: PolishNot measured1405Only GPT-5.6 Luna measured
LMArena Text: multi-turn14651434Claude Sonnet 5.5
LMArena Text: longer queries14951436Claude Sonnet 5.5
LMArena Text: writing and language14741419Claude Sonnet 5.5
LMArena Text: entertainment and media14611402Claude Sonnet 5.5
LMArena Vision: English12891263Claude Sonnet 5.5
LMArena Vision: ChineseNot measured1294Only GPT-5.6 Luna measured
LMArena Vision: reading text12971264Claude Sonnet 5.5
LMArena Vision: humorNot measured1190Only GPT-5.6 Luna measured
LMArena Vision: creative writing12421257GPT-5.6 Luna
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 Sonnet 5.5 and GPT-5.6 Luna
BenchmarkClaude Sonnet 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 Sonnet 5.5$0.0070Fits 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 5.5$0.130Fits 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 5.5$0.500Fits 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 5.5 and GPT-5.6 Luna
SpecificationAnthropic Claude Sonnet 5.5OpenAI GPT-5.6 Luna
MakerAnthropicOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 28, 2026July 9, 2026
Context window1M1.05M
Input $/Mtok$2.00$0.20
Output $/Mtok$10.00$1.20
Coding index87.358.0
Independent measurements behind it56
Cost per solved taskNot computable$0.04
SourceOpenRouter listingOpenRouter listing

Questions

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

Pick Claude Sonnet 5.5 for coding: it scores 87.3 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 8.3x cheaper ($1.20 vs $10.00 per million) and a larger context window (1.05M against 1M tokens).

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

Claude Sonnet 5.5 costs $2.00 per million input tokens and $10.00 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 Sonnet 5.5 or GPT-5.6 Luna?

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

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

88 benchmarks have a result for both models as of October 22, 2026. Claude Sonnet 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.

Compare next

Embed this comparison on your site

Free under CC BY 4.0, while the source link stays visible. Preview the frame · Terms and other embeds

<iframe src="https://llmbenchmark.ai/embed/compare/claude-sonnet-5-5-vs-gpt-5-6-luna" title="Claude Sonnet 5.5 vs GPT-5.6 Luna, LLMBenchmark.ai" width="100%" height="360" style="border:0;max-width:100%" loading="lazy"></iframe>
<p style="font:13px/1.4 sans-serif;margin:6px 0 0">Source: <a href="https://llmbenchmark.ai/compare/claude-sonnet-5-5-vs-gpt-5-6-luna">LLMBenchmark.ai, Claude Sonnet 5.5 vs GPT-5.6 Luna</a></p>