Grok 4.5 vs Muse Spark Open
Grok 4.5 leads Muse Spark Open on coding, 58.6 to 47.4 on the Vibe Coding Index, and Muse Spark Open costs 1.4x less per output token ($4.25 vs $6.00 per million). Updated October 22, 2026; 26 benchmarks have a result for both.
Grok 4.5 or Muse Spark Open: which to pick
Pick Grok 4.5 for coding: it scores 58.6 on the Vibe Coding Index against 47.4 for Muse Spark Open.
Pick Muse Spark Open for output tokens 1.4x cheaper ($4.25 vs $6.00 per million) and a larger context window (1.05M against 500K tokens).
- Shared results
- 26
- Grok 4.5 only
- 97
- Muse Spark Open only
- 2
- Like-for-like categories
- 6 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
Grok 4.5
Grok 4.5 scores 58.6 against 47.4.
6 and 4 benchmarks behind the scores
Intelligence
AA Intelligence Index
No call
Only Grok 4.5 has a AA Intelligence Index result, 38.8.
Directional only
Agentic work
AA Agentic Index
No call
Only Grok 4.5 has a AA Agentic Index result, 41.2.
Directional only
Reasoning
GPQA Diamond
No call
Only Grok 4.5 has a GPQA Diamond result, 92.9%.
Directional only
Knowledge
MMLU Pro
No call
Only Grok 4.5 has a MMLU Pro result, 89.2%.
Directional only
Web design
Design Arena: websites
Muse Spark Open
Muse Spark Open leads, 1310 against 1281.
Same board, both measured
General
Vals Index
No call
Only Muse Spark Open has a Vals Index result, 48.6%.
Directional only
Long documents
Listed context window
Muse Spark Open
Muse Spark Open takes 1.05M tokens against 500K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Muse Spark Open
Grok 4.5 $0.0050, Muse Spark Open $0.0034 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Grok 4.5 has the number, $0.62.
Directional only
At a glance
- Coding index
- Grok 4.5 58.6 from 6 benchmarks, Muse Spark Open 47.4 from 4 benchmarks.
- Widest category
- Coding, 8.8 points apart on average over 9 shared benchmarks.
- Widest single gap
- APEX-Agents: Grok 4.5 56.2% against Muse Spark Open 33.4%, 22.8 points apart on a 0 to 100 scale.
- Output price
- Grok 4.5 $6.00 against Muse Spark Open $4.25 per million output tokens, 1.4x apart.
- Context window
- Grok 4.5 takes 500K tokens, Muse Spark Open 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 | Grok 4.5 | Bars | Muse Spark Open | Ties |
|---|---|---|---|---|
| Coding | 6 | 3 | ||
| Intelligence | 0 | 1 | ||
| Agentic work | 4 | 4 | ||
| Reasoning | 2 | 1 | ||
| Web design | 1 | 2 | ||
| General | 2 | 0 | ||
| All shared boards | 15 | 11 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index63
| Benchmark | Grok 4.5 | Muse Spark Open | Leader |
|---|---|---|---|
| LiveBench coding | 94.3% | 73.6% | Grok 4.5 |
| LMArena WebDev | 1553 | 1528 | Grok 4.5 |
| AA Coding Index | 72.4 | Not measured | Only Grok 4.5 measured |
| LiveCodeBench (Vals AI) | 87.3% | Not measured | Only Grok 4.5 measured |
| SWE-bench Verified (Vals AI) | 86.6% | Not measured | Only Grok 4.5 measured |
| Terminal-Bench 4 (Vals AI) | 8.6% | 6.6% | Grok 4.5 |
| Vibe Code Bench (Vals AI) | 69.0% | 76.2% | Muse Spark Open |
| Code migration (Vals AI) | 36.6% | 21.2% | Grok 4.5 |
| ProgramBench (Vals AI) | 0.0% | Not measured | Only Grok 4.5 measured |
| IOI (Vals AI) | 40.6% | Not measured | Only Grok 4.5 measured |
| Terminal-Bench 2.1 (Vals AI) | 67.8% | Not measured | Only Grok 4.5 measured |
| SkillsBench (Vals AI) | 66.0% | Not measured | Only Grok 4.5 measured |
| CyberBench (Vals AI) | 71.0% | Not measured | Only Grok 4.5 measured |
| SciCode | 55.0% | 58.4% | Muse Spark Open |
| FrontierCode | 42.4% | Not measured | Only Grok 4.5 measured |
| WeirdML | 46.4% | Not measured | Only Grok 4.5 measured |
| ALE-Bench | 1309.3 | 1590.1 | Muse Spark Open |
| LMArena Text: coding | 1474 | Not measured | Only Grok 4.5 measured |
| LMArena Text: software and IT | 1471 | Not measured | Only Grok 4.5 measured |
| LMArena WebDev: React | 1556 | 1529 | Grok 4.5 |
| LMArena WebDev: HTML | 1567 | 1495 | Grok 4.5 |
| LMArena WebDev: from an image | 1562 | Not measured | Only Grok 4.5 measured |
| SciCode | 6.5% | Not measured | Only Grok 4.5 measured |
| Neither model has a result on the other 16 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Grok 4.5 | Muse Spark Open | Leader |
|---|---|---|---|
| AA Intelligence Index | 38.8 | Not measured | Only Grok 4.5 measured |
| Epoch Capabilities Index | 154.1 | 155.1 | Muse Spark Open |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index44
| Benchmark | Grok 4.5 | Muse Spark Open | Leader |
|---|---|---|---|
| AA Agentic Index | 41.2 | Not measured | Only Grok 4.5 measured |
| Design Arena: agents building web apps | 1218 | Not measured | Only Grok 4.5 measured |
| Design Arena: agents building full-stack apps | 1249 | Not measured | Only Grok 4.5 measured |
| Design Arena: agents building mobile apps | 1220 | Not measured | Only Grok 4.5 measured |
| Design Arena: agents building Android apps | 1236 | Not measured | Only Grok 4.5 measured |
| Design Arena: agents building Godot games | 1229 | Not measured | Only Grok 4.5 measured |
| Design Arena: agents building games | 1236 | Not measured | Only Grok 4.5 measured |
| Design Arena: HTML slides | 1205 | Not measured | Only Grok 4.5 measured |
| Design Arena: PowerPoint slides | 1230 | Not measured | Only Grok 4.5 measured |
| LiveBench research | 85.9% | 80.3% | Grok 4.5 |
| LiveBench browser | 44.0% | 36.0% | Grok 4.5 |
| LiveBench long agentic | 27.9% | 18.9% | Grok 4.5 |
| SREBench (Vals AI) | 0.8% | Not measured | Only Grok 4.5 measured |
| Finance Agent (Vals AI) | 48.4% | 61.3% | Muse Spark Open |
| Tax Agent Bench (Vals AI) | 24.9% | 26.3% | Muse Spark Open |
| Legal Research Bench (Vals AI) | 38.0% | 38.5% | Muse Spark Open |
| Harvey's Legal Agent Benchmark (Vals AI) | Not measured | 25.0% | Only Muse Spark Open measured |
| Excel Modeling Benchmark (Vals AI) | 52.9% | 53.7% | Muse Spark Open |
| Time Horizon Index (Vals AI) | 6.3% | Not measured | Only Grok 4.5 measured |
| APEX-Agents | 56.2% | 33.4% | Grok 4.5 |
| PostTrainBench | 23.4% | Not measured | Only Grok 4.5 measured |
| Vending-Bench 2 | $3,887 | Not measured | Only Grok 4.5 measured |
| LMArena Search | 1216 | Not measured | Only Grok 4.5 measured |
| Neither model has a result on the other 18 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index21
| Benchmark | Grok 4.5 | Muse Spark Open | Leader |
|---|---|---|---|
| GPQA Diamond | 92.9% | Not measured | Only Grok 4.5 measured |
| LiveBench reasoning | 87.2% | 73.7% | Grok 4.5 |
| MMMU Pro (Vals AI) | 61.8% | Not measured | Only Grok 4.5 measured |
| GPQA Diamond (Artificial Analysis run) | 93.1% | 89.0% | Grok 4.5 |
| Humanity's Last Exam (Artificial Analysis run) | 42.7% | 43.9% | Muse Spark Open |
| GPQA Diamond (Epoch AI run) | 93.4% | Not measured | Only Grok 4.5 measured |
| ARC-AGI | 87.2% | Not measured | Only Grok 4.5 measured |
| ARC-AGI-2 | 52.6% | Not measured | Only Grok 4.5 measured |
| SimpleBench | 70.0% | Not measured | Only Grok 4.5 measured |
| Chess puzzles | 35.0% | Not measured | Only Grok 4.5 measured |
| LMArena Text: hard prompts | 1462 | Not measured | Only Grok 4.5 measured |
| LMArena Text: expert | 1465 | Not measured | Only Grok 4.5 measured |
| LMArena Text: hard prompts in English | 1464 | Not measured | Only Grok 4.5 measured |
| LMArena Vision: diagrams | 1304 | Not measured | Only Grok 4.5 measured |
| LMArena Vision: homework | 1295 | Not measured | Only Grok 4.5 measured |
| Kagi LLM Benchmark | 83.5% | Not measured | Only Grok 4.5 measured |
| Neither model has a result on the other 6 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
| Benchmark | Grok 4.5 | Muse Spark Open | Leader |
|---|---|---|---|
| OTIS Mock AIME | 97.8% | Not measured | Only Grok 4.5 measured |
| FrontierMath, tiers 1 to 3 | 57.2% | Not measured | Only Grok 4.5 measured |
| FrontierMath, tier 4 | 24.4% | Not measured | Only Grok 4.5 measured |
| ProofBench | 31.0% | Not measured | Only Grok 4.5 measured |
| LMArena Text: math | 1460 | Not measured | Only Grok 4.5 measured |
| LMArena Text: mathematical work | 1482 | Not measured | Only Grok 4.5 measured |
| Neither model has a result on the other 7 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index12 boards, none shared
| Benchmark | Grok 4.5 | Muse Spark Open | Leader |
|---|---|---|---|
| MMLU Pro | 89.2% | Not measured | Only Grok 4.5 measured |
| LegalBench (Vals AI) | 86.0% | Not measured | Only Grok 4.5 measured |
| CorpFin (Vals AI) | 67.4% | Not measured | Only Grok 4.5 measured |
| TaxEval (Vals AI) | 71.7% | Not measured | Only Grok 4.5 measured |
| MortgageTax (Vals AI) | 61.8% | Not measured | Only Grok 4.5 measured |
| MedCode (Vals AI) | 43.3% | Not measured | Only Grok 4.5 measured |
| SimpleQA Verified | 48.3% | Not measured | Only Grok 4.5 measured |
| LMArena Text: science | 1464 | Not measured | Only Grok 4.5 measured |
| LMArena Text: medicine and healthcare | 1440 | Not measured | Only Grok 4.5 measured |
| LMArena Text: legal and government | 1463 | Not measured | Only Grok 4.5 measured |
| LMArena Text: business and finance | 1441 | Not measured | Only Grok 4.5 measured |
| FACTS Benchmark Suite | 50.2% | Not measured | Only Grok 4.5 measured |
| Neither model has a result on the other 6 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index12
| Benchmark | Grok 4.5 | Muse Spark Open | Leader |
|---|---|---|---|
| Design Arena: websites | 1281 | 1310 | Muse Spark Open |
| Design Arena: UI components | 1280 | Not measured | Only Grok 4.5 measured |
| Design Arena: game dev | 1264 | 1282 | Muse Spark Open |
| Design Arena: data viz | 1266 | Not measured | Only Grok 4.5 measured |
| Design Arena: 3D | 1257 | Not measured | Only Grok 4.5 measured |
| Design Arena: all code categories | 1275 | Not measured | Only Grok 4.5 measured |
| Design Arena: SVG | 1215 | Not measured | Only Grok 4.5 measured |
| Design Arena: ASCII art | 1256 | Not measured | Only Grok 4.5 measured |
| LiveBench design | 78.1% | 60.3% | Grok 4.5 |
GeneralLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Grok 4.5 | Muse Spark Open | Leader |
|---|---|---|---|
| Vals Index | Not measured | 48.6% | Only Muse Spark Open measured |
| LiveBench data analysis | 73.0% | 60.2% | Grok 4.5 |
| SAGE (Vals AI) | 35.0% | Not measured | Only Grok 4.5 measured |
| MedScribe (Vals AI) | 86.9% | Not measured | Only Grok 4.5 measured |
| Vals Multimodal Index | 63.4% | Not measured | Only Grok 4.5 measured |
| Long context reasoning (AA-LCR) | 79.3% | 78.3% | Grok 4.5 |
| DTBench | 96.5% | Not measured | Only Grok 4.5 measured |
| LMCA | 45.2% | Not measured | Only Grok 4.5 measured |
| Surface Evolver Bench | 74.4% | Not measured | Only Grok 4.5 measured |
| Furniture assembly | 22.5% | Not measured | Only Grok 4.5 measured |
| LMArena Text | 1448 | Not measured | Only Grok 4.5 measured |
| LMArena Text: instruction following | 1445 | Not measured | Only Grok 4.5 measured |
| LMArena Text: creative writing | 1442 | Not measured | Only Grok 4.5 measured |
| LMArena Vision | 1287 | Not measured | Only Grok 4.5 measured |
| LMArena Text: English | 1453 | Not measured | Only Grok 4.5 measured |
| LMArena Text: non-English | 1440 | Not measured | Only Grok 4.5 measured |
| LMArena Text: Chinese | 1495 | Not measured | Only Grok 4.5 measured |
| LMArena Text: German | 1448 | Not measured | Only Grok 4.5 measured |
| LMArena Text: Japanese | 1430 | Not measured | Only Grok 4.5 measured |
| LMArena Text: Korean | 1406 | Not measured | Only Grok 4.5 measured |
| LMArena Text: French | 1457 | Not measured | Only Grok 4.5 measured |
| LMArena Text: Spanish | 1451 | Not measured | Only Grok 4.5 measured |
| LMArena Text: Russian | 1449 | Not measured | Only Grok 4.5 measured |
| LMArena Text: Polish | 1432 | Not measured | Only Grok 4.5 measured |
| LMArena Text: multi-turn | 1456 | Not measured | Only Grok 4.5 measured |
| LMArena Text: longer queries | 1462 | Not measured | Only Grok 4.5 measured |
| LMArena Text: writing and language | 1445 | Not measured | Only Grok 4.5 measured |
| LMArena Text: entertainment and media | 1434 | Not measured | Only Grok 4.5 measured |
| LMArena Vision: English | 1285 | Not measured | Only Grok 4.5 measured |
| LMArena Vision: Chinese | 1345 | Not measured | Only Grok 4.5 measured |
| LMArena Vision: reading text | 1293 | Not measured | Only Grok 4.5 measured |
| LMArena Vision: humor | 1276 | Not measured | Only Grok 4.5 measured |
| LMArena Vision: creative writing | 1293 | Not measured | Only Grok 4.5 measured |
| LMArena Document | 1452 | Not measured | Only Grok 4.5 measured |
| Neither model has a result on the other 12 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Grok 4.5 | Muse Spark Open | 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 Open costs less
Repository review
50K input + 3K output tokens
Muse Spark Open costs less
Agent loop
200K input + 10K output tokens
Muse Spark Open 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 | SpaceXAI Grok 4.5 | Meta Muse Spark Open |
|---|---|---|
| Maker | xAI | Meta |
| Weights | No public weights listed | Open weights |
| Released | July 8, 2026 | October 15, 2026 |
| Context window | 500K | 1.05M |
| Input $/Mtok | $2.00 | $1.25 |
| Output $/Mtok | $6.00 | $4.25 |
| Coding index | 58.6 | 47.4 |
| Independent measurements behind it | 6 | 4 |
| Cost per solved task | $0.62 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Grok 4.5 better than Muse Spark Open for coding?
Pick Grok 4.5 for coding: it scores 58.6 on the Vibe Coding Index against 47.4 for Muse Spark Open. Pick Muse Spark Open for output tokens 1.4x cheaper ($4.25 vs $6.00 per million) and a larger context window (1.05M against 500K tokens).
Which is cheaper, Grok 4.5 or Muse Spark Open?
Grok 4.5 costs $2.00 per million input tokens and $6.00 per million output tokens; Muse Spark Open costs $1.25 and $4.25. Cost per solved task is known for Grok 4.5 only.
Which has the bigger context window, Grok 4.5 or Muse Spark Open?
Muse Spark Open, with 1.05M tokens against 500K.
How many benchmarks is the Grok 4.5 vs Muse Spark Open comparison based on?
26 benchmarks have a result for both models as of October 22, 2026. Grok 4.5's coding index rests on 6 independent benchmarks and Muse Spark Open's on 4. Where only one model has a result, the page says so instead of naming a winner.