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Claude Opus 4.5 vs Muse Spark 1.2

Updated October 21, 2026. 63 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Opus 4.5 Replace Muse Spark 1.2
Claude Opus 4.5Anthropic
Coding
66.8
Overall
29.1
Output $/M
$25.00
8
Muse Spark 1.2Meta
Coding
65.1
Overall
39.6
Output $/M
$4.25
55
vs boards won of 63 shared

Decision reading

Claude Opus 4.5 and Muse Spark 1.2 are level for coding, 66.8 against 65.1 on the Vibe Coding Index, so price and context decide.

Pick Muse Spark 1.2 when output tokens cost 5.9x less, or when a solved task costs $0.64 against $1.37. Pick Claude Opus 4.5 when what matters is WeirdML or Design Arena: agents building mobile apps, where it leads.

Model AClaude Opus 4.5Anthropic66.8/1002 independent benchmarks$1.37 per solved taskModel BMuse Spark 1.2Meta65.1/1002 independent benchmarks$0.64 per solved task
Shared results
63
Claude Opus 4.5 only
42
Muse Spark 1.2 only
34
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 Opus 4.5 66.8 from 2 benchmarks, Muse Spark 1.2 65.1 from 2 benchmarks.
Widest category
Coding, 11.9 points apart on average over 8 shared benchmarks.
Widest single gap
Vibe Code Bench (Vals AI): Claude Opus 4.5 20.6% against Muse Spark 1.2 79.1%, 58.5 points apart on a 0 to 100 scale.
Output price
Claude Opus 4.5 $25.00 against Muse Spark 1.2 $4.25 per million output tokens, 5.9x apart.
Context window
Claude Opus 4.5 takes 200K 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 Opus 4.5BarsMuse Spark 1.2Ties
Coding17
Intelligence02
Agentic work13
Reasoning17
Math03
Knowledge110
Web design08
General415
All shared boards855
CodingLike-for-likeFour of these boards feed the Vibe Coding Index17
Coding benchmarks for Claude Opus 4.5 and Muse Spark 1.2
BenchmarkClaude Opus 4.5Muse Spark 1.2Leader
SWE-bench Verified79.2%Not measuredOnly Claude Opus 4.5 measured
SWE-bench (full test set)52.6%Not measuredOnly Claude Opus 4.5 measured
SWE-bench Multilingual70.7%Not measuredOnly Claude Opus 4.5 measured
LiveBench codingNot measured78.2%Only Muse Spark 1.2 measured
LMArena WebDev14941534Muse Spark 1.2
AA Coding IndexNot measured72.2Only Muse Spark 1.2 measured
LiveCodeBench (Vals AI)83.7%Not measuredOnly Claude Opus 4.5 measured
SWE-bench Verified (Vals AI)76.4%86.6%Muse Spark 1.2
Terminal-Bench 4 (Vals AI)Not measured6.1%Only Muse Spark 1.2 measured
Vibe Code Bench (Vals AI)20.6%79.1%Muse Spark 1.2
Code migration (Vals AI)Not measured29.9%Only Muse Spark 1.2 measured
ProgramBench (Vals AI)Not measured0.5%Only Muse Spark 1.2 measured
IOI (Vals AI)Not measured21.8%Only Muse Spark 1.2 measured
Terminal-Bench 2.1 (Vals AI)Not measured69.7%Only Muse Spark 1.2 measured
SkillsBench (Vals AI)Not measured53.0%Only Muse Spark 1.2 measured
CyberBench (Vals AI)Not measured69.5%Only Muse Spark 1.2 measured
LiveCodeBench (Artificial Analysis run)87.1%Not measuredOnly Claude Opus 4.5 measured
SciCodeNot measured57.4%Only Muse Spark 1.2 measured
Terminal-Bench Hard (Artificial Analysis run)47.0%Not measuredOnly Claude Opus 4.5 measured
Terminal-Bench63.1%Not measuredOnly Claude Opus 4.5 measured
FrontierSWENot measured12.0%Only Muse Spark 1.2 measured
GSO-Bench26.5%Not measuredOnly Claude Opus 4.5 measured
WeirdML63.7%60.3%Claude Opus 4.5
Cybench82.0%Not measuredOnly Claude Opus 4.5 measured
LMArena Text: coding15031505Muse Spark 1.2
LMArena Text: software and IT14831505Muse Spark 1.2
LMArena WebDev: React14781526Muse Spark 1.2
LMArena WebDev: HTML15101543Muse Spark 1.2
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 Opus 4.5 and Muse Spark 1.2
BenchmarkClaude Opus 4.5Muse Spark 1.2Leader
AA Intelligence Index29.139.6Muse Spark 1.2
Epoch Capabilities Index150.1155.1Muse Spark 1.2
Agentic workLike-for-likePublic boards, shown as published, kept out of the index13
Agentic work benchmarks for Claude Opus 4.5 and Muse Spark 1.2
BenchmarkClaude Opus 4.5Muse Spark 1.2Leader
AA Agentic IndexNot measured43.2Only Muse Spark 1.2 measured
Design Arena: agents building web apps11591222Muse Spark 1.2
Design Arena: agents building full-stack apps11561210Muse Spark 1.2
Design Arena: agents building mobile apps11891182Claude Opus 4.5
Design Arena: agents building Android apps11811228Muse Spark 1.2
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
LiveBench researchNot measured67.7%Only Muse Spark 1.2 measured
LiveBench browserNot measured36.0%Only Muse Spark 1.2 measured
LiveBench long agenticNot measured21.3%Only Muse Spark 1.2 measured
SREBench (Vals AI)Not measured0.0%Only Muse Spark 1.2 measured
Finance Agent (Vals AI)Not measured60.6%Only Muse Spark 1.2 measured
Tax Agent Bench (Vals AI)Not measured32.8%Only Muse Spark 1.2 measured
Legal Research Bench (Vals AI)Not measured43.8%Only Muse Spark 1.2 measured
Excel Modeling Benchmark (Vals AI)Not measured57.0%Only Muse Spark 1.2 measured
BioMysteryBench (Vals AI)Not measured64.8%Only Muse Spark 1.2 measured
τ²-Bench Telecom89.5%Not measuredOnly Claude Opus 4.5 measured
APEX-AgentsNot measured45.4%Only Muse Spark 1.2 measured
METR time horizons75.0%Not measuredOnly Claude Opus 4.5 measured
Remote Labor Index3.8%Not measuredOnly Claude Opus 4.5 measured
GDPval45.5%Not measuredOnly Claude Opus 4.5 measured
BALROG43.5%Not measuredOnly Claude Opus 4.5 measured
DeepResearch Bench54.8%Not measuredOnly Claude Opus 4.5 measured
OSWorld66.3%Not measuredOnly Claude Opus 4.5 measured
Vending-Bench 2$4,967Not measuredOnly Claude Opus 4.5 measured
Neither model has a result on the other 13 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index17
Reasoning benchmarks for Claude Opus 4.5 and Muse Spark 1.2
BenchmarkClaude Opus 4.5Muse Spark 1.2Leader
GPQA Diamond85.9%Not measuredOnly Claude Opus 4.5 measured
LiveBench reasoningNot measured90.0%Only Muse Spark 1.2 measured
MMMU Pro (Vals AI)83.0%86.1%Muse Spark 1.2
GPQA Diamond (Artificial Analysis run)86.6%90.4%Muse Spark 1.2
Humanity's Last Exam (Artificial Analysis run)30.1%45.5%Muse Spark 1.2
GPQA Diamond (Epoch AI run)86.0%Not measuredOnly Claude Opus 4.5 measured
ARC-AGI80.0%Not measuredOnly Claude Opus 4.5 measured
ARC-AGI-237.6%Not measuredOnly Claude Opus 4.5 measured
SimpleBench62.0%74.5%Muse Spark 1.2
Chess puzzles14.0%27.0%Muse Spark 1.2
Mystery game puzzles22.0%Not measuredOnly Claude Opus 4.5 measured
EBR-bench14.3%Not measuredOnly Claude Opus 4.5 measured
VPCT40.0%Not measuredOnly Claude Opus 4.5 measured
LMArena Text: hard prompts14761489Muse Spark 1.2
LMArena Text: expert14871475Claude Opus 4.5
LMArena Text: hard prompts in English14821487Muse Spark 1.2
LMArena Vision: diagramsNot measured1317Only Muse Spark 1.2 measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index03
Math benchmarks for Claude Opus 4.5 and Muse Spark 1.2
BenchmarkClaude Opus 4.5Muse Spark 1.2Leader
AIME95.4%Not measuredOnly Claude Opus 4.5 measured
MGSM (Vals AI)95.2%Not measuredOnly Claude Opus 4.5 measured
AA Math Index91.3Not measuredOnly Claude Opus 4.5 measured
AIME 2025 (Artificial Analysis run)91.3%Not measuredOnly Claude Opus 4.5 measured
OTIS Mock AIME86.1%Not measuredOnly Claude Opus 4.5 measured
FrontierMath, tiers 1 to 334.4%Not measuredOnly Claude Opus 4.5 measured
FrontierMath, tier 44.9%Not measuredOnly Claude Opus 4.5 measured
ProofBench36.0%43.0%Muse Spark 1.2
LMArena Text: math14631484Muse Spark 1.2
LMArena Text: mathematical work14681480Muse Spark 1.2
Neither model has a result on the other 3 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index110
Knowledge benchmarks for Claude Opus 4.5 and Muse Spark 1.2
BenchmarkClaude Opus 4.5Muse Spark 1.2Leader
MMLU Pro87.3%88.3%Muse Spark 1.2
LegalBench (Vals AI)84.6%85.3%Muse Spark 1.2
CaseLaw (Vals AI)62.6%Not measuredOnly Claude Opus 4.5 measured
CorpFin (Vals AI)65.1%70.9%Muse Spark 1.2
TaxEval (Vals AI)74.9%80.4%Muse Spark 1.2
MortgageTax (Vals AI)68.7%65.4%Claude Opus 4.5
MedQA (Vals AI)95.9%Not measuredOnly Claude Opus 4.5 measured
MedCode (Vals AI)49.2%49.4%Muse Spark 1.2
MMLU Pro (Artificial Analysis run)89.5%Not measuredOnly Claude Opus 4.5 measured
SimpleQA Verified45.7%60.3%Muse Spark 1.2
GeoBench75.0%Not measuredOnly Claude Opus 4.5 measured
LMArena Text: science14541500Muse Spark 1.2
LMArena Text: medicine and healthcare14441496Muse Spark 1.2
LMArena Text: legal and government14591517Muse Spark 1.2
LMArena Text: business and finance14481484Muse Spark 1.2
Neither model has a result on the other 2 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index08
Web design benchmarks for Claude Opus 4.5 and Muse Spark 1.2
BenchmarkClaude Opus 4.5Muse Spark 1.2Leader
Design Arena: websites12471313Muse Spark 1.2
Design Arena: UI components12381300Muse Spark 1.2
Design Arena: game dev12291302Muse Spark 1.2
Design Arena: data viz12431334Muse Spark 1.2
Design Arena: 3D12141301Muse Spark 1.2
Design Arena: all code categories12421313Muse Spark 1.2
Design Arena: SVG11801285Muse Spark 1.2
Design Arena: ASCII art11901284Muse Spark 1.2
LiveBench designNot measured67.1%Only Muse Spark 1.2 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index415
General benchmarks for Claude Opus 4.5 and Muse Spark 1.2
BenchmarkClaude Opus 4.5Muse Spark 1.2Leader
LiveBench data analysisNot measured76.5%Only Muse Spark 1.2 measured
Public Benefits Bench (Vals AI)Not measured68.5%Only Muse Spark 1.2 measured
SAGE (Vals AI)52.1%47.7%Claude Opus 4.5
MedScribe (Vals AI)85.3%90.1%Muse Spark 1.2
Vals Multimodal IndexNot measured69.8%Only Muse Spark 1.2 measured
IFBench58.0%Not measuredOnly Claude Opus 4.5 measured
Long context reasoning (AA-LCR)77.3%79.0%Muse Spark 1.2
DTBench89.9%94.7%Muse Spark 1.2
LMCA44.5%48.4%Muse Spark 1.2
CL-bench21.1%Not measuredOnly Claude Opus 4.5 measured
Furniture assembly28.3%Not measuredOnly Claude Opus 4.5 measured
LMArena Text14511482Muse Spark 1.2
LMArena Text: instruction following14781462Claude Opus 4.5
LMArena Text: creative writing14451436Claude Opus 4.5
LMArena VisionNot measured1304Only Muse Spark 1.2 measured
LMArena Text: English14611483Muse Spark 1.2
LMArena Text: non-English14381476Muse Spark 1.2
LMArena Text: Chinese14701509Muse Spark 1.2
LMArena Text: German1449Not measuredOnly Claude Opus 4.5 measured
LMArena Text: Japanese1417Not measuredOnly Claude Opus 4.5 measured
LMArena Text: Korean14241462Muse Spark 1.2
LMArena Text: French14711495Muse Spark 1.2
LMArena Text: Spanish14571484Muse Spark 1.2
LMArena Text: Russian14471483Muse Spark 1.2
LMArena Text: Polish1439Not measuredOnly Claude Opus 4.5 measured
LMArena Text: multi-turn14661502Muse Spark 1.2
LMArena Text: longer queries14791473Claude Opus 4.5
LMArena Text: writing and language14521453Muse Spark 1.2
LMArena Text: entertainment and media14341443Muse Spark 1.2
LMArena Vision: EnglishNot measured1291Only Muse Spark 1.2 measured
LMArena Vision: reading textNot measured1313Only Muse Spark 1.2 measured
LMArena Document1462Not measuredOnly Claude Opus 4.5 measured
Neither model has a result on the other 14 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Opus 4.5 and Muse Spark 1.2
BenchmarkClaude Opus 4.5Muse 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 Opus 4.5$0.018Fits 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 Opus 4.5$0.325Fits 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 Opus 4.5$1.25Exceeds the context window
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 Opus 4.5 and Muse Spark 1.2
SpecificationAnthropic Claude Opus 4.5Meta Muse Spark 1.2
MakerAnthropicMeta
WeightsNo public weights listedNo public weights listed
ReleasedNovember 24, 2025August 5, 2026
Context window200K1.05M
Input $/Mtok$5.00$1.25
Output $/Mtok$25.00$4.25
Coding index66.865.1
Independent measurements behind it22
Cost per solved task$1.37$0.64
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 4.5 better than Muse Spark 1.2 for coding?

Claude Opus 4.5 and Muse Spark 1.2 are level for coding, 66.8 against 65.1 on the Vibe Coding Index, so price and context decide. Pick Muse Spark 1.2 when output tokens cost 5.9x less, or when a solved task costs $0.64 against $1.37. Pick Claude Opus 4.5 when what matters is WeirdML or Design Arena: agents building mobile apps, where it leads.

Which is cheaper, Claude Opus 4.5 or Muse Spark 1.2?

Claude Opus 4.5 costs $5.00 per million input tokens and $25.00 per million output tokens; Muse Spark 1.2 costs $1.25 and $4.25. Per solved SWE-bench Verified task, Claude Opus 4.5 costs $1.37 and Muse Spark 1.2 $0.64.

Which has the bigger context window, Claude Opus 4.5 or Muse Spark 1.2?

Muse Spark 1.2, with 1.05M tokens against 200K.

How many benchmarks is the Claude Opus 4.5 vs Muse Spark 1.2 comparison based on?

63 benchmarks have a result for both models as of October 21, 2026. Claude Opus 4.5'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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