Claude Opus 5.5 vs Muse Spark 1.2
Claude Opus 5.5 leads Muse Spark 1.2 on coding, 88.8 to 55.7 on the Vibe Coding Index, and Muse Spark 1.2 costs 4.7x less per output token ($4.25 vs $20.00 per million). Updated October 22, 2026; 76 benchmarks have a result for both.
Claude Opus 5.5 or Muse Spark 1.2: which to pick
Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 55.7 for Muse Spark 1.2.
Pick Muse Spark 1.2 for output tokens 4.7x cheaper ($4.25 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).
- Shared results
- 76
- Claude Opus 5.5 only
- 33
- Muse Spark 1.2 only
- 21
- 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.
Coding
Vibe Coding Index, six public coding benchmarks
Claude Opus 5.5
Claude Opus 5.5 scores 88.8 against 55.7.
5 benchmarks behind each score
Intelligence
AA Intelligence Index
Claude Opus 5.5
Claude Opus 5.5 leads, 57.6 against 39.6.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Muse Spark 1.2 has a AA Agentic Index result, 43.2.
Directional only
Knowledge
MMLU Pro
No call
Only Muse Spark 1.2 has a MMLU Pro result, 88.3%.
Directional only
Web design
Design Arena: websites
Claude Opus 5.5
Claude Opus 5.5 leads, 1335 against 1312.
Same board, both measured
General
Vals Index
No call
Only Claude Opus 5.5 has a Vals Index result, 70.2%.
Directional only
Long documents
Listed context window
Muse Spark 1.2
Muse Spark 1.2 takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Muse Spark 1.2
Claude Opus 5.5 $0.014, Muse Spark 1.2 $0.0034 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Muse Spark 1.2 has the number, $0.64.
Directional only
At a glance
- Coding index
- Claude Opus 5.5 88.8 from 5 benchmarks, Muse Spark 1.2 55.7 from 5 benchmarks.
- Widest category
- Coding, 26.1 points apart on average over 15 shared benchmarks.
- Widest single gap
- Terminal-Bench 4 (Vals AI): Claude Opus 5.5 65.2% against Muse Spark 1.2 6.1%, 78.8 points apart on a 0 to 100 scale.
- Output price
- Claude Opus 5.5 $20.00 against Muse Spark 1.2 $4.25 per million output tokens, 4.7x apart.
- Context window
- Claude Opus 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.
| Category | Claude Opus 5.5 | Bars | Muse Spark 1.2 | Ties |
|---|---|---|---|---|
| Coding | 15 | 0 | ||
| Intelligence | 2 | 0 | ||
| Agentic work | 11 | 1 | ||
| Reasoning | 7 | 0 | ||
| Math | 3 | 0 | ||
| Knowledge | 6 | 0 | ||
| Web design | 8 | 0 | ||
| General | 20 | 3 | ||
| All shared boards | 72 | 4 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index150
| Benchmark | Claude Opus 5.5 | Muse Spark 1.2 | Leader |
|---|---|---|---|
| LiveBench coding | 96.3% | 78.2% | Claude Opus 5.5 |
| LMArena WebDev | 1807 | 1534 | Claude Opus 5.5 |
| AA Coding Index | Not measured | 72.2 | Only Muse Spark 1.2 measured |
| SWE-bench Verified (Vals AI) | Not measured | 86.6% | Only Muse Spark 1.2 measured |
| Terminal-Bench 4 (Vals AI) | 65.2% | 6.1% | Claude Opus 5.5 |
| Vibe Code Bench (Vals AI) | 90.3% | 79.1% | Claude Opus 5.5 |
| Code migration (Vals AI) | 66.7% | 29.9% | Claude Opus 5.5 |
| ProgramBench (Vals AI) | 18.5% | 0.5% | Claude Opus 5.5 |
| IOI (Vals AI) | 95.1% | 21.8% | Claude Opus 5.5 |
| Terminal-Bench 2.1 (Vals AI) | 87.6% | 69.7% | Claude Opus 5.5 |
| SWE-bench Multimodal (Vals AI) | 70.2% | Not measured | Only Claude Opus 5.5 measured |
| Vibe Code Bench 1-100 (Vals AI) | 30.4% | Not measured | Only Claude Opus 5.5 measured |
| SkillsBench (Vals AI) | Not measured | 53.0% | Only Muse Spark 1.2 measured |
| CyberBench (Vals AI) | 74.6% | 69.5% | Claude Opus 5.5 |
| SciCode | 66.9% | 57.4% | Claude Opus 5.5 |
| FrontierCode | 54.6% | Not measured | Only Claude Opus 5.5 measured |
| FrontierSWE | 62.3% | 12.0% | Claude Opus 5.5 |
| WeirdML | Not measured | 60.3% | Only Muse Spark 1.2 measured |
| MirrorCode | 77.4% | Not measured | Only Claude Opus 5.5 measured |
| ALE-Bench | 2147.4 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: coding | 1545 | 1505 | Claude Opus 5.5 |
| LMArena Text: software and IT | 1538 | 1505 | Claude Opus 5.5 |
| LMArena WebDev: React | 1855 | 1526 | Claude Opus 5.5 |
| LMArena WebDev: HTML | 1753 | 1543 | Claude Opus 5.5 |
| LMArena WebDev: from an image | 1753 | Not measured | Only Claude Opus 5.5 measured |
| SciCode | 18.5% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 13 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Opus 5.5 | Muse Spark 1.2 | Leader |
|---|---|---|---|
| AA Intelligence Index | 57.6 | 39.6 | Claude Opus 5.5 |
| Epoch Capabilities Index | 168.8 | 155.1 | Claude Opus 5.5 |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index111
| Benchmark | Claude Opus 5.5 | Muse Spark 1.2 | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 43.2 | Only Muse Spark 1.2 measured |
| Design Arena: agents building web apps | 1316 | 1221 | Claude Opus 5.5 |
| Design Arena: agents building full-stack apps | Not measured | 1210 | Only Muse Spark 1.2 measured |
| Design Arena: agents building mobile apps | 1308 | 1181 | Claude Opus 5.5 |
| Design Arena: agents building Android apps | Not measured | 1222 | Only Muse Spark 1.2 measured |
| Design Arena: agents building games | Not measured | 1179 | Only Muse Spark 1.2 measured |
| Design Arena: HTML slides | Not measured | 1085 | Only Muse Spark 1.2 measured |
| Design Arena: PowerPoint slides | Not measured | 1172 | Only Muse Spark 1.2 measured |
| Design Arena: spreadsheets | 1368 | Not measured | Only Claude Opus 5.5 measured |
| LiveBench research | 85.0% | 67.7% | Claude Opus 5.5 |
| LiveBench browser | 80.0% | 36.0% | Claude Opus 5.5 |
| LiveBench long agentic | 85.0% | 21.3% | Claude Opus 5.5 |
| SREBench (Vals AI) | 33.6% | 0.0% | Claude Opus 5.5 |
| Finance Agent (Vals AI) | 58.6% | 60.6% | Muse Spark 1.2 |
| Tax Agent Bench (Vals AI) | 45.6% | 32.8% | Claude Opus 5.5 |
| Legal Research Bench (Vals AI) | 50.5% | 43.8% | Claude Opus 5.5 |
| Harvey's Legal Agent Benchmark (Vals AI) | 9.2% | Not measured | Only Claude Opus 5.5 measured |
| Excel Modeling Benchmark (Vals AI) | 75.9% | 57.0% | Claude Opus 5.5 |
| BioMysteryBench (Vals AI) | 79.3% | 64.8% | Claude Opus 5.5 |
| Terminal-Bench-Science (Vals AI) | 47.1% | Not measured | Only Claude Opus 5.5 measured |
| Vals Science Index | 58.7% | Not measured | Only Claude Opus 5.5 measured |
| Time Horizon Index (Vals AI) | 91.3% | Not measured | Only Claude Opus 5.5 measured |
| CUA-bench (Vals AI) | 14.0% | Not measured | Only Claude Opus 5.5 measured |
| Robo-bench (Vals AI) | 14.6% | Not measured | Only Claude Opus 5.5 measured |
| APEX-Agents | 73.5% | 45.4% | Claude Opus 5.5 |
| Remote Labor Index | 21.3% | Not measured | Only Claude Opus 5.5 measured |
| SpireClimb | 3.3% | Not measured | Only Claude Opus 5.5 measured |
| Vending-Bench 2 | $9,235 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Search | 1213 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 12 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index70
| Benchmark | Claude Opus 5.5 | Muse Spark 1.2 | Leader |
|---|---|---|---|
| LiveBench reasoning | 92.2% | 90.0% | Claude Opus 5.5 |
| MysteryMechanism (Vals AI) | 49.5% | Not measured | Only Claude Opus 5.5 measured |
| MMMU Pro (Vals AI) | Not measured | 86.1% | Only Muse Spark 1.2 measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 90.4% | Only Muse Spark 1.2 measured |
| Humanity's Last Exam (Artificial Analysis run) | 61.4% | 45.5% | Claude Opus 5.5 |
| GPQA Diamond (Epoch AI run) | 90.6% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI | 98.5% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI-2 | 93.3% | Not measured | Only Claude Opus 5.5 measured |
| SimpleBench | Not measured | 74.5% | Only Muse Spark 1.2 measured |
| Chess puzzles | 67.0% | 27.0% | Claude Opus 5.5 |
| Mystery game puzzles | 71.0% | Not measured | Only Claude Opus 5.5 measured |
| EBR-bench | 71.4% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: hard prompts | 1536 | 1489 | Claude Opus 5.5 |
| LMArena Text: expert | 1549 | 1475 | Claude Opus 5.5 |
| LMArena Text: hard prompts in English | 1535 | 1487 | Claude Opus 5.5 |
| LMArena Vision: diagrams | 1345 | 1317 | Claude Opus 5.5 |
| LMArena Vision: homework | 1362 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 5 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Claude Opus 5.5 | Muse Spark 1.2 | Leader |
|---|---|---|---|
| OTIS Mock AIME | 100.0% | Not measured | Only Claude Opus 5.5 measured |
| FrontierMath, tiers 1 to 3 | 91.2% | Not measured | Only Claude Opus 5.5 measured |
| FrontierMath, tier 4 | 95.0% | Not measured | Only Claude Opus 5.5 measured |
| ProofBench | 100.0% | 43.0% | Claude Opus 5.5 |
| LMArena Text: math | 1518 | 1484 | Claude Opus 5.5 |
| LMArena Text: mathematical work | 1516 | 1480 | Claude Opus 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
| Benchmark | Claude Opus 5.5 | Muse Spark 1.2 | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 88.3% | Only Muse Spark 1.2 measured |
| LegalBench (Vals AI) | Not measured | 85.3% | Only Muse Spark 1.2 measured |
| CorpFin (Vals AI) | Not measured | 70.9% | Only Muse Spark 1.2 measured |
| TaxEval (Vals AI) | Not measured | 80.4% | Only Muse Spark 1.2 measured |
| MortgageTax (Vals AI) | Not measured | 65.4% | Only Muse Spark 1.2 measured |
| MedCode (Vals AI) | 49.8% | 49.4% | Claude Opus 5.5 |
| SimpleQA Verified | 72.2% | 60.3% | Claude Opus 5.5 |
| LMArena Text: science | 1524 | 1500 | Claude Opus 5.5 |
| LMArena Text: medicine and healthcare | 1509 | 1496 | Claude Opus 5.5 |
| LMArena Text: legal and government | 1518 | 1517 | Claude Opus 5.5 |
| LMArena Text: business and finance | 1494 | 1484 | Claude Opus 5.5 |
| FACTS Benchmark Suite | 65.3% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 6 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index80
| Benchmark | Claude Opus 5.5 | Muse Spark 1.2 | Leader |
|---|---|---|---|
| Design Arena: websites | 1335 | 1312 | Claude Opus 5.5 |
| Design Arena: UI components | 1385 | 1298 | Claude Opus 5.5 |
| Design Arena: game dev | 1461 | 1301 | Claude Opus 5.5 |
| Design Arena: data viz | 1397 | 1334 | Claude Opus 5.5 |
| Design Arena: 3D | 1476 | 1301 | Claude Opus 5.5 |
| Design Arena: all code categories | 1390 | 1312 | Claude Opus 5.5 |
| Design Arena: SVG | 1329 | 1284 | Claude Opus 5.5 |
| Design Arena: ASCII art | Not measured | 1284 | Only Muse Spark 1.2 measured |
| LiveBench design | 86.9% | 67.1% | Claude Opus 5.5 |
GeneralLike-for-likePublic boards, shown as published, kept out of the index203
| Benchmark | Claude Opus 5.5 | Muse Spark 1.2 | Leader |
|---|---|---|---|
| Vals Index | 70.2% | Not measured | Only Claude Opus 5.5 measured |
| LiveBench data analysis | 80.3% | 76.5% | Claude Opus 5.5 |
| Public Benefits Bench (Vals AI) | 70.6% | 68.5% | Claude Opus 5.5 |
| SAGE (Vals AI) | 45.8% | 47.7% | Muse Spark 1.2 |
| MedScribe (Vals AI) | 91.4% | 90.1% | Claude Opus 5.5 |
| Vals Multimodal Index | Not measured | 69.8% | Only Muse Spark 1.2 measured |
| Long context reasoning (AA-LCR) | 84.7% | 79.0% | Claude Opus 5.5 |
| DTBench | 98.9% | 94.7% | Claude Opus 5.5 |
| LMCA | 68.2% | 48.4% | Claude Opus 5.5 |
| Furniture assembly | 83.3% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text | 1516 | 1482 | Claude Opus 5.5 |
| LMArena Text: instruction following | 1537 | 1462 | Claude Opus 5.5 |
| LMArena Text: creative writing | 1535 | 1436 | Claude Opus 5.5 |
| LMArena Vision | 1321 | 1304 | Claude Opus 5.5 |
| LMArena Text: English | 1519 | 1483 | Claude Opus 5.5 |
| LMArena Text: non-English | 1507 | 1476 | Claude Opus 5.5 |
| LMArena Text: Chinese | 1582 | 1509 | Claude Opus 5.5 |
| LMArena Text: Japanese | 1534 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: Korean | Not measured | 1462 | Only Muse Spark 1.2 measured |
| LMArena Text: French | 1493 | 1495 | Muse Spark 1.2 |
| LMArena Text: Spanish | 1508 | 1484 | Claude Opus 5.5 |
| LMArena Text: Russian | 1517 | 1483 | Claude Opus 5.5 |
| LMArena Text: multi-turn | 1501 | 1502 | Muse Spark 1.2 |
| LMArena Text: longer queries | 1532 | 1473 | Claude Opus 5.5 |
| LMArena Text: writing and language | 1532 | 1453 | Claude Opus 5.5 |
| LMArena Text: entertainment and media | 1515 | 1443 | Claude Opus 5.5 |
| LMArena Vision: English | 1317 | 1291 | Claude Opus 5.5 |
| LMArena Vision: reading text | 1326 | 1313 | Claude Opus 5.5 |
| LMArena Vision: creative writing | 1320 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 17 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Opus 5.5 | Muse Spark 1.2 | Leader |
|---|---|---|---|
| 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
Muse Spark 1.2 costs less
Repository review
50K input + 3K output tokens
Muse Spark 1.2 costs less
Agent loop
200K input + 10K output tokens
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.
| Specification | Anthropic Claude Opus 5.5 | Meta Muse Spark 1.2 |
|---|---|---|
| Maker | Anthropic | Meta |
| Weights | No public weights listed | No public weights listed |
| Released | September 22, 2026 | August 5, 2026 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $4.00 | $1.25 |
| Output $/Mtok | $20.00 | $4.25 |
| Coding index | 88.8 | 55.7 |
| Independent measurements behind it | 5 | 5 |
| Cost per solved task | Not computable | $0.64 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Opus 5.5 better than Muse Spark 1.2 for coding?
Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 55.7 for Muse Spark 1.2. Pick Muse Spark 1.2 for output tokens 4.7x cheaper ($4.25 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).
Which is cheaper, Claude Opus 5.5 or Muse Spark 1.2?
Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 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 Opus 5.5 or Muse Spark 1.2?
Muse Spark 1.2, with 1.05M tokens against 1M.
How many benchmarks is the Claude Opus 5.5 vs Muse Spark 1.2 comparison based on?
76 benchmarks have a result for both models as of October 22, 2026. Claude Opus 5.5's coding index rests on 5 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.