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GPT-5.6 Luna vs Muse Spark 1.2

GPT-5.6 Luna leads Muse Spark 1.2 on coding, 58.0 to 55.7 on the Vibe Coding Index, and GPT-5.6 Luna costs 3.5x less per output token ($1.20 vs $4.25 per million). Updated October 22, 2026; 89 benchmarks have a result for both.

Replace GPT-5.6 Luna Replace Muse Spark 1.2
GPT-5.6 LunaOpenAI
Coding
58.0
Overall
61.6
Output $/M
$1.20
22
Muse Spark 1.2Meta
Coding
55.7
Overall
60.4
Output $/M
$4.25
67
vs boards won of 89 shared

GPT-5.6 Luna or Muse Spark 1.2: which to pick

Pick GPT-5.6 Luna for coding: it scores 58.0 on the Vibe Coding Index against 55.7 for Muse Spark 1.2.

Pick Muse Spark 1.2 for work measured by LiveBench coding or LMArena WebDev, where it leads.

Model AGPT-5.6 LunaOpenAI58.0/1006 independent benchmarks$0.04 per solved taskModel BMuse Spark 1.2Meta55.7/1005 independent benchmarks$0.64 per solved task
Shared results
89
GPT-5.6 Luna only
31
Muse Spark 1.2 only
8
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
GPT-5.6 Luna 58.0 from 6 benchmarks, Muse Spark 1.2 55.7 from 5 benchmarks.
Widest category
Web design, 12.5 points apart on average over 9 shared benchmarks.
Widest single gap
IOI (Vals AI): GPT-5.6 Luna 61.8% against Muse Spark 1.2 21.8%, 40.0 points apart on a 0 to 100 scale.
Output price
GPT-5.6 Luna $1.20 against Muse Spark 1.2 $4.25 per million output tokens, 3.5x apart.
Context window
GPT-5.6 Luna takes 1.05M tokens, Muse Spark 1.2 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
CategoryGPT-5.6 LunaBarsMuse Spark 1.2Ties
Coding810
Intelligence11
Agentic work47
Reasoning37
Math12
Knowledge110
Web design18
General322
All shared boards2267
CodingLike-for-likeSix of these boards feed the Vibe Coding Index810
Coding benchmarks for GPT-5.6 Luna and Muse Spark 1.2
BenchmarkGPT-5.6 LunaMuse Spark 1.2Leader
LiveBench coding73.6%78.2%Muse Spark 1.2
LMArena WebDev15181534Muse Spark 1.2
AA Coding Index71.472.2Muse Spark 1.2
SWE-bench Verified (Vals AI)93.0%86.6%GPT-5.6 Luna
Terminal-Bench 4 (Vals AI)11.6%6.1%GPT-5.6 Luna
Vibe Code Bench (Vals AI)77.1%79.1%Muse Spark 1.2
Code migration (Vals AI)44.5%29.9%GPT-5.6 Luna
ProgramBench (Vals AI)0.0%0.5%Muse Spark 1.2
IOI (Vals AI)61.8%21.8%GPT-5.6 Luna
Terminal-Bench 2.1 (Vals AI)79.0%69.7%GPT-5.6 Luna
Vibe Code Bench 1-100 (Vals AI)22.6%Not measuredOnly GPT-5.6 Luna measured
SkillsBench (Vals AI)60.5%53.0%GPT-5.6 Luna
CyberBench (Vals AI)73.6%69.5%GPT-5.6 Luna
SciCode53.6%57.4%Muse Spark 1.2
FrontierCode39.8%Not measuredOnly GPT-5.6 Luna measured
FrontierSWENot measured12.0%Only Muse Spark 1.2 measured
WeirdML60.9%60.3%GPT-5.6 Luna
ALE-Bench1667.4Not measuredOnly GPT-5.6 Luna measured
LMArena Text: coding14661505Muse Spark 1.2
LMArena Text: software and IT14631505Muse Spark 1.2
LMArena WebDev: React15081526Muse Spark 1.2
LMArena WebDev: HTML15201543Muse Spark 1.2
LMArena WebDev: from an image1517Not measuredOnly GPT-5.6 Luna measured
SciCode6.2%Not measuredOnly GPT-5.6 Luna measured
Neither model has a result on the other 19 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index11
Intelligence benchmarks for GPT-5.6 Luna and Muse Spark 1.2
BenchmarkGPT-5.6 LunaMuse Spark 1.2Leader
AA Intelligence Index37.339.6Muse Spark 1.2
Epoch Capabilities Index156.5155.1GPT-5.6 Luna
Agentic workLike-for-likePublic boards, shown as published, kept out of the index47
Agentic work benchmarks for GPT-5.6 Luna and Muse Spark 1.2
BenchmarkGPT-5.6 LunaMuse Spark 1.2Leader
AA Agentic Index42.143.2Muse Spark 1.2
Design Arena: agents building web appsNot measured1221Only Muse Spark 1.2 measured
Design Arena: agents building full-stack appsNot measured1210Only Muse Spark 1.2 measured
Design Arena: agents building mobile appsNot measured1181Only Muse Spark 1.2 measured
Design Arena: agents building Android appsNot measured1222Only Muse Spark 1.2 measured
Design Arena: agents building gamesNot measured1178Only Muse Spark 1.2 measured
Design Arena: HTML slidesNot measured1074Only Muse Spark 1.2 measured
Design Arena: PowerPoint slidesNot measured1170Only Muse Spark 1.2 measured
LiveBench research51.0%67.7%Muse Spark 1.2
LiveBench browser68.0%36.0%GPT-5.6 Luna
LiveBench long agentic30.4%21.3%GPT-5.6 Luna
SREBench (Vals AI)1.5%0.0%GPT-5.6 Luna
Finance Agent (Vals AI)55.0%60.6%Muse Spark 1.2
Tax Agent Bench (Vals AI)24.8%32.8%Muse Spark 1.2
Legal Research Bench (Vals AI)36.5%43.8%Muse Spark 1.2
Excel Modeling Benchmark (Vals AI)67.1%57.0%GPT-5.6 Luna
BioMysteryBench (Vals AI)61.5%64.8%Muse Spark 1.2
Terminal-Bench-Science (Vals AI)0.0%Not measuredOnly GPT-5.6 Luna measured
Vals Science Index25.3%Not measuredOnly GPT-5.6 Luna measured
APEX-Agents43.0%45.4%Muse Spark 1.2
BALROG45.6%Not measuredOnly GPT-5.6 Luna measured
Vending-Bench 2$4,095Not measuredOnly GPT-5.6 Luna measured
Neither model has a result on the other 20 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index37
Reasoning benchmarks for GPT-5.6 Luna and Muse Spark 1.2
BenchmarkGPT-5.6 LunaMuse Spark 1.2Leader
GPQA Diamond91.7%Not measuredOnly GPT-5.6 Luna measured
LiveBench reasoning85.6%90.0%Muse Spark 1.2
MysteryMechanism (Vals AI)14.4%Not measuredOnly GPT-5.6 Luna measured
MMMU Pro (Vals AI)85.0%86.1%Muse Spark 1.2
GPQA Diamond (Artificial Analysis run)91.1%90.4%GPT-5.6 Luna
Humanity's Last Exam (Artificial Analysis run)39.5%45.5%Muse Spark 1.2
GPQA Diamond (Epoch AI run)91.6%Not measuredOnly GPT-5.6 Luna measured
ARC-AGI88.0%Not measuredOnly GPT-5.6 Luna measured
ARC-AGI-259.5%Not measuredOnly GPT-5.6 Luna measured
SimpleBench46.8%74.5%Muse Spark 1.2
Chess puzzles43.0%27.0%GPT-5.6 Luna
Mystery game puzzles21.0%Not measuredOnly GPT-5.6 Luna measured
LMArena Text: hard prompts14511489Muse Spark 1.2
LMArena Text: expert14781475GPT-5.6 Luna
LMArena Text: hard prompts in English14601487Muse Spark 1.2
LMArena Vision: diagrams12731317Muse Spark 1.2
LMArena Vision: homework1282Not measuredOnly GPT-5.6 Luna measured
Kagi LLM Benchmark49.1%Not measuredOnly GPT-5.6 Luna measured
Neither model has a result on the other 5 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index12
Math benchmarks for GPT-5.6 Luna and Muse Spark 1.2
BenchmarkGPT-5.6 LunaMuse Spark 1.2Leader
OTIS Mock AIME98.3%Not measuredOnly GPT-5.6 Luna measured
FrontierMath, tiers 1 to 382.1%Not measuredOnly GPT-5.6 Luna measured
FrontierMath, tier 461.0%Not measuredOnly GPT-5.6 Luna measured
ProofBench60.0%43.0%GPT-5.6 Luna
LMArena Text: math14591484Muse Spark 1.2
LMArena Text: mathematical work14701480Muse Spark 1.2
Neither model has a result on the other 8 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index110
Knowledge benchmarks for GPT-5.6 Luna and Muse Spark 1.2
BenchmarkGPT-5.6 LunaMuse Spark 1.2Leader
MMLU Pro86.0%88.3%Muse Spark 1.2
LegalBench (Vals AI)84.0%85.3%Muse Spark 1.2
CorpFin (Vals AI)64.2%70.9%Muse Spark 1.2
TaxEval (Vals AI)76.2%80.4%Muse Spark 1.2
MortgageTax (Vals AI)67.3%65.4%GPT-5.6 Luna
MedCode (Vals AI)42.4%49.4%Muse Spark 1.2
SimpleQA Verified41.0%60.3%Muse Spark 1.2
LMArena Text: science14331500Muse Spark 1.2
LMArena Text: medicine and healthcare13991496Muse Spark 1.2
LMArena Text: legal and government14461517Muse Spark 1.2
LMArena Text: business and finance14391484Muse Spark 1.2
FACTS Benchmark Suite35.0%Not measuredOnly GPT-5.6 Luna measured
Neither model has a result on the other 8 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index18
Web design benchmarks for GPT-5.6 Luna and Muse Spark 1.2
BenchmarkGPT-5.6 LunaMuse Spark 1.2Leader
Design Arena: websites12551312Muse Spark 1.2
Design Arena: UI components12481299Muse Spark 1.2
Design Arena: game dev11951300Muse Spark 1.2
Design Arena: data viz12121334Muse Spark 1.2
Design Arena: 3D11211300Muse Spark 1.2
Design Arena: all code categories12301312Muse Spark 1.2
Design Arena: SVG11931283Muse Spark 1.2
Design Arena: ASCII art11421284Muse Spark 1.2
LiveBench design76.0%67.1%GPT-5.6 Luna
GeneralLike-for-likePublic boards, shown as published, kept out of the index322
General benchmarks for GPT-5.6 Luna and Muse Spark 1.2
BenchmarkGPT-5.6 LunaMuse Spark 1.2Leader
LiveBench data analysis78.0%76.5%GPT-5.6 Luna
Public Benefits Bench (Vals AI)61.2%68.5%Muse Spark 1.2
SAGE (Vals AI)44.2%47.7%Muse Spark 1.2
MedScribe (Vals AI)84.4%90.1%Muse Spark 1.2
Vals Multimodal Index69.1%69.8%Muse Spark 1.2
Long context reasoning (AA-LCR)83.7%79.0%GPT-5.6 Luna
DTBench89.1%94.7%Muse Spark 1.2
LMCA48.5%48.4%GPT-5.6 Luna
Surface Evolver Bench61.9%Not measuredOnly GPT-5.6 Luna measured
Furniture assembly42.5%Not measuredOnly GPT-5.6 Luna measured
LMArena Text14311482Muse Spark 1.2
LMArena Text: instruction following14371462Muse Spark 1.2
LMArena Text: creative writing13961436Muse Spark 1.2
LMArena Vision12571304Muse Spark 1.2
LMArena Text: English14411483Muse Spark 1.2
LMArena Text: non-English14171476Muse Spark 1.2
LMArena Text: Chinese14701509Muse Spark 1.2
LMArena Text: German1455Not measuredOnly GPT-5.6 Luna measured
LMArena Text: Japanese1415Not measuredOnly GPT-5.6 Luna measured
LMArena Text: Korean14151462Muse Spark 1.2
LMArena Text: French14581495Muse Spark 1.2
LMArena Text: Spanish14461484Muse Spark 1.2
LMArena Text: Russian14271483Muse Spark 1.2
LMArena Text: Polish1405Not measuredOnly GPT-5.6 Luna measured
LMArena Text: multi-turn14341502Muse Spark 1.2
LMArena Text: longer queries14361473Muse Spark 1.2
LMArena Text: writing and language14191453Muse Spark 1.2
LMArena Text: entertainment and media14021443Muse Spark 1.2
LMArena Vision: English12631291Muse Spark 1.2
LMArena Vision: Chinese1294Not measuredOnly GPT-5.6 Luna measured
LMArena Vision: reading text12641313Muse Spark 1.2
LMArena Vision: humor1190Not measuredOnly GPT-5.6 Luna measured
LMArena Vision: creative writing1257Not measuredOnly GPT-5.6 Luna measured
LMArena Document1457Not measuredOnly GPT-5.6 Luna measured
EQ-Bench 41156Not measuredOnly GPT-5.6 Luna measured
Neither model has a result on the other 13 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GPT-5.6 Luna and Muse Spark 1.2
BenchmarkGPT-5.6 LunaMuse Spark 1.2Leader
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

GPT-5.6 Luna$0.0008Fits in one request
Muse Spark 1.2$0.0034Fits in one request

GPT-5.6 Luna costs less

Repository review

50K input + 3K output tokens

GPT-5.6 Luna$0.014Fits in one request
Muse Spark 1.2$0.075Fits in one request

GPT-5.6 Luna costs less

Agent loop

200K input + 10K output tokens

GPT-5.6 Luna$0.052Fits in one request
Muse Spark 1.2$0.292Fits 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 GPT-5.6 Luna and Muse Spark 1.2
SpecificationOpenAI GPT-5.6 LunaMeta Muse Spark 1.2
MakerOpenAIMeta
WeightsNo public weights listedNo public weights listed
ReleasedJuly 9, 2026August 5, 2026
Context window1.05M1.05M
Input $/Mtok$0.20$1.25
Output $/Mtok$1.20$4.25
Coding index58.055.7
Independent measurements behind it65
Cost per solved task$0.04$0.64
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5.6 Luna better than Muse Spark 1.2 for coding?

Pick GPT-5.6 Luna for coding: it scores 58.0 on the Vibe Coding Index against 55.7 for Muse Spark 1.2. Pick Muse Spark 1.2 for work measured by LiveBench coding or LMArena WebDev, where it leads.

Which is cheaper, GPT-5.6 Luna or Muse Spark 1.2?

GPT-5.6 Luna costs $0.20 per million input tokens and $1.20 per million output tokens; Muse Spark 1.2 costs $1.25 and $4.25. Per solved SWE-bench Verified task, GPT-5.6 Luna costs $0.04 and Muse Spark 1.2 $0.64.

Which has the bigger context window, GPT-5.6 Luna or Muse Spark 1.2?

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

How many benchmarks is the GPT-5.6 Luna vs Muse Spark 1.2 comparison based on?

89 benchmarks have a result for both models as of October 22, 2026. GPT-5.6 Luna's coding index rests on 6 independent benchmarks and Muse Spark 1.2's on 5. Where only one model has a result, the page says so instead of naming a winner.

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