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GPT-5.6 Luna vs Muse Spark 1.3

GPT-5.6 Luna leads Muse Spark 1.3 on coding, 58.0 to 57.4 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; 85 benchmarks have a result for both.

Replace GPT-5.6 Luna Replace Muse Spark 1.3
GPT-5.6 LunaOpenAI
Coding
58.0
Overall
61.6
Output $/M
$1.20
12
Muse Spark 1.3Meta
Coding
57.4
Overall
68.6
Output $/M
$4.25
73
vs boards won of 85 shared

GPT-5.6 Luna or Muse Spark 1.3: which to pick

GPT-5.6 Luna and Muse Spark 1.3 are level for coding, 58.0 against 57.4 on the Vibe Coding Index, so price and context decide.

Pick Muse Spark 1.3 for work measured by LiveBench coding or LMArena WebDev, where it leads. Pick GPT-5.6 Luna for output tokens 3.5x cheaper ($1.20 vs $4.25 per million) and a larger context window (1.05M against 1.05M tokens).

Model AGPT-5.6 LunaOpenAI58.0/1006 independent benchmarks$0.04 per solved taskModel BMuse Spark 1.3Meta57.4/1004 independent benchmarksNo cost per solved task
Shared results
85
GPT-5.6 Luna only
35
Muse Spark 1.3 only
11
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 1.3 57.4 from 4 benchmarks.
Widest category
Web design, 15.1 points apart on average over 9 shared benchmarks.
Widest single gap
Design Arena: 3D: GPT-5.6 Luna 1121 against Muse Spark 1.3 1358, 29.6 points apart on a 0 to 100 scale.
Output price
GPT-5.6 Luna $1.20 against Muse Spark 1.3 $4.25 per million output tokens, 3.5x apart.
Context window
GPT-5.6 Luna takes 1.05M tokens, Muse Spark 1.3 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 1.3Ties
Coding512
Intelligence02
Agentic work19
Reasoning19
Math33
Knowledge04
Web design18
General126
All shared boards1273
CodingLike-for-likeSix of these boards feed the Vibe Coding Index512
Coding benchmarks for GPT-5.6 Luna and Muse Spark 1.3
BenchmarkGPT-5.6 LunaMuse Spark 1.3Leader
LiveBench coding73.6%90.2%Muse Spark 1.3
LMArena WebDev15181659Muse Spark 1.3
AA Coding Index71.475.8Muse Spark 1.3
SWE-bench Verified (Vals AI)93.0%Not measuredOnly GPT-5.6 Luna measured
Terminal-Bench 4 (Vals AI)11.6%10.6%GPT-5.6 Luna
Vibe Code Bench (Vals AI)77.1%82.9%Muse Spark 1.3
Code migration (Vals AI)44.5%27.6%GPT-5.6 Luna
ProgramBench (Vals AI)0.0%0.5%Muse Spark 1.3
IOI (Vals AI)61.8%43.9%GPT-5.6 Luna
Terminal-Bench 2.1 (Vals AI)79.0%72.3%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%Not measuredOnly GPT-5.6 Luna measured
CyberBench (Vals AI)73.6%69.4%GPT-5.6 Luna
SciCode53.6%59.7%Muse Spark 1.3
FrontierCode39.8%Not measuredOnly GPT-5.6 Luna measured
FrontierSWENot measured25.8%Only Muse Spark 1.3 measured
WeirdML60.9%Not measuredOnly GPT-5.6 Luna measured
ALE-Bench1667.41688.3Muse Spark 1.3
LMArena Text: coding14661510Muse Spark 1.3
LMArena Text: software and IT14631511Muse Spark 1.3
LMArena WebDev: React15081672Muse Spark 1.3
LMArena WebDev: HTML15201653Muse Spark 1.3
LMArena WebDev: from an image15171640Muse Spark 1.3
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 index02
Intelligence benchmarks for GPT-5.6 Luna and Muse Spark 1.3
BenchmarkGPT-5.6 LunaMuse Spark 1.3Leader
AA Intelligence Index37.348.1Muse Spark 1.3
Epoch Capabilities Index156.5157.2Muse Spark 1.3
Agentic workLike-for-likePublic boards, shown as published, kept out of the index19
Agentic work benchmarks for GPT-5.6 Luna and Muse Spark 1.3
BenchmarkGPT-5.6 LunaMuse Spark 1.3Leader
AA Agentic Index42.155.5Muse Spark 1.3
Design Arena: agents building web appsNot measured1297Only Muse Spark 1.3 measured
Design Arena: agents building full-stack appsNot measured1295Only Muse Spark 1.3 measured
Design Arena: agents building mobile appsNot measured1217Only Muse Spark 1.3 measured
Design Arena: agents building Godot gamesNot measured1241Only Muse Spark 1.3 measured
Design Arena: PowerPoint slidesNot measured1217Only Muse Spark 1.3 measured
Design Arena: spreadsheetsNot measured1075Only Muse Spark 1.3 measured
LiveBench research51.0%68.6%Muse Spark 1.3
LiveBench browser68.0%80.0%Muse Spark 1.3
LiveBench long agentic30.4%40.4%Muse Spark 1.3
SREBench (Vals AI)1.5%Not measuredOnly GPT-5.6 Luna measured
Finance Agent (Vals AI)55.0%58.9%Muse Spark 1.3
Tax Agent Bench (Vals AI)24.8%36.0%Muse Spark 1.3
Legal Research Bench (Vals AI)36.5%40.9%Muse Spark 1.3
Excel Modeling Benchmark (Vals AI)67.1%62.7%GPT-5.6 Luna
BioMysteryBench (Vals AI)61.5%Not measuredOnly GPT-5.6 Luna measured
Terminal-Bench-Science (Vals AI)0.0%4.3%Muse Spark 1.3
Vals Science Index25.3%Not measuredOnly GPT-5.6 Luna measured
APEX-Agents43.0%58.6%Muse Spark 1.3
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 21 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index19
Reasoning benchmarks for GPT-5.6 Luna and Muse Spark 1.3
BenchmarkGPT-5.6 LunaMuse Spark 1.3Leader
GPQA Diamond91.7%Not measuredOnly GPT-5.6 Luna measured
LiveBench reasoning85.6%89.7%Muse Spark 1.3
MysteryMechanism (Vals AI)14.4%Not measuredOnly GPT-5.6 Luna measured
MMMU Pro (Vals AI)85.0%Not measuredOnly GPT-5.6 Luna measured
GPQA Diamond (Artificial Analysis run)91.1%94.1%Muse Spark 1.3
Humanity's Last Exam (Artificial Analysis run)39.5%48.7%Muse Spark 1.3
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%Not measuredOnly GPT-5.6 Luna measured
Chess puzzles43.0%37.0%GPT-5.6 Luna
Mystery game puzzles21.0%25.0%Muse Spark 1.3
LMArena Text: hard prompts14511503Muse Spark 1.3
LMArena Text: expert14781519Muse Spark 1.3
LMArena Text: hard prompts in English14601500Muse Spark 1.3
LMArena Vision: diagrams12731330Muse Spark 1.3
LMArena Vision: homework12821296Muse Spark 1.3
Kagi LLM Benchmark49.1%Not measuredOnly GPT-5.6 Luna measured
Humanity's Last Exam (Scale run)Not measured25.4%Only Muse Spark 1.3 measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index33
Math benchmarks for GPT-5.6 Luna and Muse Spark 1.3
BenchmarkGPT-5.6 LunaMuse Spark 1.3Leader
OTIS Mock AIME98.3%99.2%Muse Spark 1.3
FrontierMath, tiers 1 to 382.1%74.4%GPT-5.6 Luna
FrontierMath, tier 461.0%46.3%GPT-5.6 Luna
ProofBench60.0%58.0%GPT-5.6 Luna
LMArena Text: math14591497Muse Spark 1.3
LMArena Text: mathematical work14701491Muse Spark 1.3
MathArenaNot measured43.0%Only Muse Spark 1.3 measured
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index04
Knowledge benchmarks for GPT-5.6 Luna and Muse Spark 1.3
BenchmarkGPT-5.6 LunaMuse Spark 1.3Leader
MMLU Pro86.0%Not measuredOnly GPT-5.6 Luna measured
LegalBench (Vals AI)84.0%Not measuredOnly GPT-5.6 Luna measured
CorpFin (Vals AI)64.2%Not measuredOnly GPT-5.6 Luna measured
TaxEval (Vals AI)76.2%Not measuredOnly GPT-5.6 Luna measured
MortgageTax (Vals AI)67.3%Not measuredOnly GPT-5.6 Luna measured
MedCode (Vals AI)42.4%Not measuredOnly GPT-5.6 Luna measured
SimpleQA Verified41.0%Not measuredOnly GPT-5.6 Luna measured
LMArena Text: science14331507Muse Spark 1.3
LMArena Text: medicine and healthcare13991493Muse Spark 1.3
LMArena Text: legal and government14461499Muse Spark 1.3
LMArena Text: business and finance14391490Muse Spark 1.3
FACTS Benchmark Suite35.0%Not measuredOnly GPT-5.6 Luna measured
PRBench FinanceNot measured59.5%Only Muse Spark 1.3 measured
PRBench LegalNot measured61.6%Only Muse Spark 1.3 measured
Neither model has a result on the other 6 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 1.3
BenchmarkGPT-5.6 LunaMuse Spark 1.3Leader
Design Arena: websites12551356Muse Spark 1.3
Design Arena: UI components12481350Muse Spark 1.3
Design Arena: game dev11951328Muse Spark 1.3
Design Arena: data viz12121344Muse Spark 1.3
Design Arena: 3D11211358Muse Spark 1.3
Design Arena: all code categories12301352Muse Spark 1.3
Design Arena: SVG11931301Muse Spark 1.3
Design Arena: ASCII art11421283Muse Spark 1.3
LiveBench design76.0%74.8%GPT-5.6 Luna
GeneralLike-for-likePublic boards, shown as published, kept out of the index126
General benchmarks for GPT-5.6 Luna and Muse Spark 1.3
BenchmarkGPT-5.6 LunaMuse Spark 1.3Leader
LiveBench data analysis78.0%79.6%Muse Spark 1.3
Public Benefits Bench (Vals AI)61.2%Not measuredOnly GPT-5.6 Luna measured
SAGE (Vals AI)44.2%Not measuredOnly GPT-5.6 Luna measured
MedScribe (Vals AI)84.4%Not measuredOnly GPT-5.6 Luna measured
Vals Multimodal Index69.1%Not measuredOnly GPT-5.6 Luna measured
Long context reasoning (AA-LCR)83.7%83.0%GPT-5.6 Luna
DTBench89.1%96.5%Muse Spark 1.3
LMCA48.5%53.9%Muse Spark 1.3
Surface Evolver Bench61.9%Not measuredOnly GPT-5.6 Luna measured
Furniture assembly42.5%Not measuredOnly GPT-5.6 Luna measured
LMArena Text14311490Muse Spark 1.3
LMArena Text: instruction following14371479Muse Spark 1.3
LMArena Text: creative writing13961462Muse Spark 1.3
LMArena Vision12571308Muse Spark 1.3
LMArena Text: English14411495Muse Spark 1.3
LMArena Text: non-English14171481Muse Spark 1.3
LMArena Text: Chinese14701532Muse Spark 1.3
LMArena Text: German14551513Muse Spark 1.3
LMArena Text: Japanese14151470Muse Spark 1.3
LMArena Text: Korean14151490Muse Spark 1.3
LMArena Text: French14581511Muse Spark 1.3
LMArena Text: Spanish14461496Muse Spark 1.3
LMArena Text: Russian14271491Muse Spark 1.3
LMArena Text: Polish14051490Muse Spark 1.3
LMArena Text: multi-turn14341487Muse Spark 1.3
LMArena Text: longer queries14361488Muse Spark 1.3
LMArena Text: writing and language14191470Muse Spark 1.3
LMArena Text: entertainment and media14021457Muse Spark 1.3
LMArena Vision: English12631298Muse Spark 1.3
LMArena Vision: Chinese12941384Muse Spark 1.3
LMArena Vision: reading text12641319Muse Spark 1.3
LMArena Vision: humor11901293Muse Spark 1.3
LMArena Vision: creative writing12571296Muse Spark 1.3
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 1.3
BenchmarkGPT-5.6 LunaMuse Spark 1.3Leader
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 1.3$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 1.3$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 1.3$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 1.3
SpecificationOpenAI GPT-5.6 LunaMeta Muse Spark 1.3
MakerOpenAIMeta
WeightsNo public weights listedNo public weights listed
ReleasedJuly 9, 2026September 2, 2026
Context window1.05M1.05M
Input $/Mtok$0.20$1.25
Output $/Mtok$1.20$4.25
Coding index58.057.4
Independent measurements behind it64
Cost per solved task$0.04Not computable
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5.6 Luna better than Muse Spark 1.3 for coding?

GPT-5.6 Luna and Muse Spark 1.3 are level for coding, 58.0 against 57.4 on the Vibe Coding Index, so price and context decide. Pick Muse Spark 1.3 for work measured by LiveBench coding or LMArena WebDev, where it leads. Pick GPT-5.6 Luna for output tokens 3.5x cheaper ($1.20 vs $4.25 per million) and a larger context window (1.05M against 1.05M tokens).

Which is cheaper, GPT-5.6 Luna or Muse Spark 1.3?

GPT-5.6 Luna costs $0.20 per million input tokens and $1.20 per million output tokens; Muse Spark 1.3 costs $1.25 and $4.25. Cost per solved task is known for GPT-5.6 Luna only.

Which has the bigger context window, GPT-5.6 Luna or Muse Spark 1.3?

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

How many benchmarks is the GPT-5.6 Luna vs Muse Spark 1.3 comparison based on?

85 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 1.3's on 4. Where only one model has a result, the page says so instead of naming a winner.

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<p style="font:13px/1.4 sans-serif;margin:6px 0 0">Source: <a href="https://llmbenchmark.ai/compare/gpt-5-6-luna-vs-meta-muse-spark-1-3">LLMBenchmark.ai, GPT-5.6 Luna vs Muse Spark 1.3</a></p>