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Claude Sonnet 5.5 vs Muse Spark 1.2

Updated October 21, 2026. 75 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Sonnet 5.5 Replace Muse Spark 1.2
Claude Sonnet 5.5Anthropic
Coding
88.9
Overall
56.0
Output $/M
$10.00
57
Muse Spark 1.2Meta
Coding
65.1
Overall
39.6
Output $/M
$4.25
18
vs boards won of 75 shared

Decision reading

Pick Claude Sonnet 5.5 for coding: it scores 88.9 on the Vibe Coding Index against 65.1 for Muse Spark 1.2.

Pick Muse Spark 1.2 when output tokens cost 2.4x less, or when the context window is larger, 1.05M against 1M tokens.

Model AClaude Sonnet 5.5Anthropic88.9/1002 independent benchmarksNo cost per solved taskModel BMuse Spark 1.2Meta65.1/1002 independent benchmarks$0.64 per solved task
Shared results
75
Claude Sonnet 5.5 only
20
Muse Spark 1.2 only
22
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 5.5 88.9 from 2 benchmarks, Muse Spark 1.2 65.1 from 2 benchmarks.
Widest category
Coding, 21.9 points apart on average over 15 shared benchmarks.
Widest single gap
IOI (Vals AI): Claude Sonnet 5.5 83.1% against Muse Spark 1.2 21.8%, 61.3 points apart on a 0 to 100 scale.
Output price
Claude Sonnet 5.5 $10.00 against Muse Spark 1.2 $4.25 per million output tokens, 2.4x apart.
Context window
Claude Sonnet 5.5 takes 1M 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
CategoryClaude Sonnet 5.5BarsMuse Spark 1.2Ties
Coding132
Intelligence20
Agentic work111
Reasoning70
Math30
Knowledge15
Web design70
General1310
All shared boards5718
CodingLike-for-likeFour of these boards feed the Vibe Coding Index132
Coding benchmarks for Claude Sonnet 5.5 and Muse Spark 1.2
BenchmarkClaude Sonnet 5.5Muse Spark 1.2Leader
LiveBench coding94.7%78.2%Claude Sonnet 5.5
LMArena WebDev17681534Claude Sonnet 5.5
AA Coding IndexNot measured72.2Only Muse Spark 1.2 measured
SWE-bench Verified (Vals AI)Not measured86.6%Only Muse Spark 1.2 measured
Terminal-Bench 4 (Vals AI)64.1%6.1%Claude Sonnet 5.5
Vibe Code Bench (Vals AI)92.4%79.1%Claude Sonnet 5.5
Code migration (Vals AI)69.8%29.9%Claude Sonnet 5.5
ProgramBench (Vals AI)6.5%0.5%Claude Sonnet 5.5
IOI (Vals AI)83.1%21.8%Claude Sonnet 5.5
Terminal-Bench 2.1 (Vals AI)83.2%69.7%Claude Sonnet 5.5
SWE-bench Multimodal (Vals AI)58.3%Not measuredOnly Claude Sonnet 5.5 measured
SkillsBench (Vals AI)Not measured53.0%Only Muse Spark 1.2 measured
CyberBench (Vals AI)59.6%69.5%Muse Spark 1.2
SciCode61.0%57.4%Claude Sonnet 5.5
FrontierCode52.1%Not measuredOnly Claude Sonnet 5.5 measured
FrontierSWE61.9%12.0%Claude Sonnet 5.5
WeirdMLNot measured60.3%Only Muse Spark 1.2 measured
ALE-Bench1819.1Not measuredOnly Claude Sonnet 5.5 measured
LMArena Text: coding15131505Claude Sonnet 5.5
LMArena Text: software and IT15041505Muse Spark 1.2
LMArena WebDev: React18171526Claude Sonnet 5.5
LMArena WebDev: HTML17411543Claude Sonnet 5.5
LMArena WebDev: from an image1737Not measuredOnly Claude Sonnet 5.5 measured
Neither model has a result on the other 15 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Sonnet 5.5 and Muse Spark 1.2
BenchmarkClaude Sonnet 5.5Muse Spark 1.2Leader
AA Intelligence Index56.039.6Claude Sonnet 5.5
Epoch Capabilities Index166.2155.1Claude Sonnet 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index111
Agentic work benchmarks for Claude Sonnet 5.5 and Muse Spark 1.2
BenchmarkClaude Sonnet 5.5Muse Spark 1.2Leader
AA Agentic IndexNot measured43.2Only Muse Spark 1.2 measured
Design Arena: agents building web apps13031222Claude Sonnet 5.5
Design Arena: agents building full-stack appsNot measured1210Only Muse Spark 1.2 measured
Design Arena: agents building mobile apps12651182Claude Sonnet 5.5
Design Arena: agents building Android appsNot measured1228Only Muse Spark 1.2 measured
Design Arena: agents building gamesNot measured1179Only Muse Spark 1.2 measured
Design Arena: HTML slidesNot measured1135Only Muse Spark 1.2 measured
Design Arena: PowerPoint slidesNot measured1198Only Muse Spark 1.2 measured
Design Arena: spreadsheets1245Not measuredOnly Claude Sonnet 5.5 measured
LiveBench research83.6%67.7%Claude Sonnet 5.5
LiveBench browser84.0%36.0%Claude Sonnet 5.5
LiveBench long agentic78.8%21.3%Claude Sonnet 5.5
SREBench (Vals AI)30.1%0.0%Claude Sonnet 5.5
Finance Agent (Vals AI)58.1%60.6%Muse Spark 1.2
Tax Agent Bench (Vals AI)42.0%32.8%Claude Sonnet 5.5
Legal Research Bench (Vals AI)48.1%43.8%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%57.0%Claude Sonnet 5.5
BioMysteryBench (Vals AI)81.1%64.8%Claude Sonnet 5.5
Terminal-Bench-Science (Vals AI)47.1%Not measuredOnly Claude Sonnet 5.5 measured
Vals Science Index59.1%Not measuredOnly Claude Sonnet 5.5 measured
APEX-Agents75.5%45.4%Claude Sonnet 5.5
SpireClimb1.3%Not measuredOnly Claude Sonnet 5.5 measured
Vending-Bench 2$11,165Not measuredOnly Claude Sonnet 5.5 measured
Neither model has a result on the other 15 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index70
Reasoning benchmarks for Claude Sonnet 5.5 and Muse Spark 1.2
BenchmarkClaude Sonnet 5.5Muse Spark 1.2Leader
LiveBench reasoning91.6%90.0%Claude Sonnet 5.5
MysteryMechanism (Vals AI)49.1%Not measuredOnly Claude Sonnet 5.5 measured
MMMU Pro (Vals AI)Not measured86.1%Only Muse Spark 1.2 measured
GPQA Diamond (Artificial Analysis run)Not measured90.4%Only Muse Spark 1.2 measured
Humanity's Last Exam (Artificial Analysis run)55.0%45.5%Claude Sonnet 5.5
GPQA Diamond (Epoch AI run)95.6%Not measuredOnly Claude Sonnet 5.5 measured
SimpleBenchNot measured74.5%Only Muse Spark 1.2 measured
Chess puzzles59.0%27.0%Claude Sonnet 5.5
Mystery game puzzles65.0%Not measuredOnly Claude Sonnet 5.5 measured
LMArena Text: hard prompts14941489Claude Sonnet 5.5
LMArena Text: expert15311475Claude Sonnet 5.5
LMArena Text: hard prompts in English15021487Claude Sonnet 5.5
LMArena Vision: diagrams13291317Claude Sonnet 5.5
LMArena Vision: homework1331Not measuredOnly Claude Sonnet 5.5 measured
Neither model has a result on the other 7 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index30
Math benchmarks for Claude Sonnet 5.5 and Muse Spark 1.2
BenchmarkClaude Sonnet 5.5Muse Spark 1.2Leader
OTIS Mock AIME100.0%Not measuredOnly Claude Sonnet 5.5 measured
FrontierMath, tiers 1 to 388.8%Not measuredOnly Claude Sonnet 5.5 measured
FrontierMath, tier 480.5%Not measuredOnly Claude Sonnet 5.5 measured
ProofBench100.0%43.0%Claude Sonnet 5.5
LMArena Text: math14971484Claude Sonnet 5.5
LMArena Text: mathematical work15101480Claude 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 index15
Knowledge benchmarks for Claude Sonnet 5.5 and Muse Spark 1.2
BenchmarkClaude Sonnet 5.5Muse Spark 1.2Leader
MMLU ProNot measured88.3%Only Muse Spark 1.2 measured
LegalBench (Vals AI)Not measured85.3%Only Muse Spark 1.2 measured
CorpFin (Vals AI)Not measured70.9%Only Muse Spark 1.2 measured
TaxEval (Vals AI)Not measured80.4%Only Muse Spark 1.2 measured
MortgageTax (Vals AI)Not measured65.4%Only Muse Spark 1.2 measured
MedCode (Vals AI)52.9%49.4%Claude Sonnet 5.5
SimpleQA Verified46.5%60.3%Muse Spark 1.2
LMArena Text: science14831500Muse Spark 1.2
LMArena Text: medicine and healthcare14641496Muse Spark 1.2
LMArena Text: legal and government14831517Muse Spark 1.2
LMArena Text: business and finance14681484Muse Spark 1.2
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 Muse Spark 1.2
BenchmarkClaude Sonnet 5.5Muse Spark 1.2Leader
Design Arena: websites13261313Claude Sonnet 5.5
Design Arena: UI components13671300Claude Sonnet 5.5
Design Arena: game dev14691302Claude Sonnet 5.5
Design Arena: data viz13891334Claude Sonnet 5.5
Design Arena: 3D14581301Claude Sonnet 5.5
Design Arena: all code categories13641313Claude Sonnet 5.5
Design Arena: SVGNot measured1285Only Muse Spark 1.2 measured
Design Arena: ASCII artNot measured1284Only Muse Spark 1.2 measured
LiveBench design85.0%67.1%Claude Sonnet 5.5
GeneralLike-for-likePublic boards, shown as published, kept out of the index1310
General benchmarks for Claude Sonnet 5.5 and Muse Spark 1.2
BenchmarkClaude Sonnet 5.5Muse Spark 1.2Leader
Vals Index70.8%Not measuredOnly Claude Sonnet 5.5 measured
LiveBench data analysis59.5%76.5%Muse Spark 1.2
Public Benefits Bench (Vals AI)67.2%68.5%Muse Spark 1.2
SAGE (Vals AI)51.8%47.7%Claude Sonnet 5.5
MedScribe (Vals AI)91.1%90.1%Claude Sonnet 5.5
Vals Multimodal IndexNot measured69.8%Only Muse Spark 1.2 measured
Long context reasoning (AA-LCR)82.7%79.0%Claude Sonnet 5.5
DTBench97.3%94.7%Claude Sonnet 5.5
LMCA68.3%48.4%Claude Sonnet 5.5
Furniture assembly75.0%Not measuredOnly Claude Sonnet 5.5 measured
LMArena Text14731482Muse Spark 1.2
LMArena Text: instruction following14921462Claude Sonnet 5.5
LMArena Text: creative writing14671436Claude Sonnet 5.5
LMArena Vision12871304Muse Spark 1.2
LMArena Text: English14841483Claude Sonnet 5.5
LMArena Text: non-English14561476Muse Spark 1.2
LMArena Text: Chinese15351509Claude Sonnet 5.5
LMArena Text: KoreanNot measured1462Only Muse Spark 1.2 measured
LMArena Text: French14991495Claude Sonnet 5.5
LMArena Text: Spanish14511484Muse Spark 1.2
LMArena Text: Russian14541483Muse Spark 1.2
LMArena Text: multi-turn14651502Muse Spark 1.2
LMArena Text: longer queries14951473Claude Sonnet 5.5
LMArena Text: writing and language14741453Claude Sonnet 5.5
LMArena Text: entertainment and media14611443Claude Sonnet 5.5
LMArena Vision: English12891291Muse Spark 1.2
LMArena Vision: reading text12971313Muse Spark 1.2
LMArena Vision: creative writing1242Not measuredOnly Claude Sonnet 5.5 measured
Neither model has a result on the other 18 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 Muse Spark 1.2
BenchmarkClaude Sonnet 5.5Muse 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

Claude Sonnet 5.5$0.0070Fits in one request
Muse Spark 1.2$0.0034Fits in one request

Muse Spark 1.2 costs less

Repository review

50K input + 3K output tokens

Claude Sonnet 5.5$0.130Fits in one request
Muse Spark 1.2$0.075Fits in one request

Muse Spark 1.2 costs less

Agent loop

200K input + 10K output tokens

Claude Sonnet 5.5$0.500Fits in one request
Muse Spark 1.2$0.292Fits in one request

Muse Spark 1.2 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 Muse Spark 1.2
SpecificationAnthropic Claude Sonnet 5.5Meta Muse Spark 1.2
MakerAnthropicMeta
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 28, 2026August 5, 2026
Context window1M1.05M
Input $/Mtok$2.00$1.25
Output $/Mtok$10.00$4.25
Coding index88.965.1
Independent measurements behind it22
Cost per solved taskNot computable$0.64
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Sonnet 5.5 better than Muse Spark 1.2 for coding?

Pick Claude Sonnet 5.5 for coding: it scores 88.9 on the Vibe Coding Index against 65.1 for Muse Spark 1.2. Pick Muse Spark 1.2 when output tokens cost 2.4x less, or when the context window is larger, 1.05M against 1M tokens.

Which is cheaper, Claude Sonnet 5.5 or Muse Spark 1.2?

Claude Sonnet 5.5 costs $2.00 per million input tokens and $10.00 per million output tokens; Muse Spark 1.2 costs $1.25 and $4.25. Cost per solved task is known for Muse Spark 1.2 only.

Which has the bigger context window, Claude Sonnet 5.5 or Muse Spark 1.2?

Muse Spark 1.2, with 1.05M tokens against 1M.

How many benchmarks is the Claude Sonnet 5.5 vs Muse Spark 1.2 comparison based on?

75 benchmarks have a result for both models as of October 21, 2026. Claude Sonnet 5.5's coding index rests on 2 independent benchmarks and Muse Spark 1.2's on 2. 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/claude-sonnet-5-5-vs-meta-muse-spark-1-2">LLMBenchmark.ai, Claude Sonnet 5.5 vs Muse Spark 1.2</a></p>