GPT-5.4 Mini vs Muse Spark Open
Muse Spark Open leads GPT-5.4 Mini on coding, 47.4 to 35.8 on the Vibe Coding Index, at about the same output price ($4.25 vs $4.50 per million). Updated October 22, 2026; 16 benchmarks have a result for both.
GPT-5.4 Mini or Muse Spark Open: which to pick
Pick Muse Spark Open for coding: it scores 47.4 on the Vibe Coding Index against 35.8 for GPT-5.4 Mini, though on 4 benchmarks against 5.
GPT-5.4 Mini is neither cheaper nor larger in context, and leads no benchmark both models were measured on.
- Shared results
- 16
- GPT-5.4 Mini only
- 73
- Muse Spark Open only
- 12
- Like-for-like categories
- 5 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
Muse Spark Open
Muse Spark Open scores 47.4 against 35.8.
5 and 4 benchmarks behind the scores
Intelligence
AA Intelligence Index
No call
Only GPT-5.4 Mini has a AA Intelligence Index result, 24.1.
Directional only
Agentic work
AA Agentic Index
No call
Only GPT-5.4 Mini has a AA Agentic Index result, 17.9.
Directional only
Reasoning
GPQA Diamond
No call
Only GPT-5.4 Mini has a GPQA Diamond result, 83.1%.
Directional only
Math
AIME
No call
Only GPT-5.4 Mini has a AIME result, 95.6%.
Directional only
Knowledge
MMLU Pro
No call
Only GPT-5.4 Mini has a MMLU Pro result, 84.5%.
Directional only
Web design
Design Arena: websites
No call
Only Muse Spark Open has a Design Arena: websites result, 1310.
Directional only
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 400K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-5.4 Mini
GPT-5.4 Mini $0.0030, Muse Spark Open $0.0034 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only GPT-5.4 Mini has the number, $0.70.
Directional only
At a glance
- Coding index
- GPT-5.4 Mini 35.8 from 5 benchmarks, Muse Spark Open 47.4 from 4 benchmarks.
- Widest category
- Agentic work, 16.9 points apart on average over 4 shared benchmarks.
- Widest single gap
- Vibe Code Bench (Vals AI): GPT-5.4 Mini 48.0% against Muse Spark Open 76.2%, 28.2 points apart on a 0 to 100 scale.
- Output price
- GPT-5.4 Mini $4.50 against Muse Spark Open $4.25 per million output tokens, 1.1x apart.
- Context window
- GPT-5.4 Mini takes 400K 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 | GPT-5.4 Mini | Bars | Muse Spark Open | Ties |
|---|---|---|---|---|
| Coding | 0 | 8 | ||
| Intelligence | 0 | 1 | ||
| Agentic work | 0 | 4 | ||
| Reasoning | 0 | 2 | ||
| General | 0 | 1 | ||
| All shared boards | 0 | 16 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index08
| Benchmark | GPT-5.4 Mini | Muse Spark Open | Leader |
|---|---|---|---|
| LiveBench coding | Not measured | 73.6% | Only Muse Spark Open measured |
| LMArena WebDev | 1397 | 1528 | Muse Spark Open |
| AA Coding Index | 56.1 | Not measured | Only GPT-5.4 Mini measured |
| LiveCodeBench (Vals AI) | 81.5% | Not measured | Only GPT-5.4 Mini measured |
| SWE-bench Verified (Vals AI) | 73.0% | Not measured | Only GPT-5.4 Mini measured |
| Terminal-Bench 4 (Vals AI) | 2.5% | 6.6% | Muse Spark Open |
| Vibe Code Bench (Vals AI) | 48.0% | 76.2% | Muse Spark Open |
| Code migration (Vals AI) | 12.9% | 21.2% | Muse Spark Open |
| ProgramBench (Vals AI) | 0.0% | Not measured | Only GPT-5.4 Mini measured |
| Terminal-Bench 2.1 (Vals AI) | 54.7% | Not measured | Only GPT-5.4 Mini measured |
| SciCode | 52.1% | 58.4% | Muse Spark Open |
| Terminal-Bench Hard (Artificial Analysis run) | 52.3% | Not measured | Only GPT-5.4 Mini measured |
| FrontierCode | 27.0% | Not measured | Only GPT-5.4 Mini measured |
| WeirdML | 60.3% | Not measured | Only GPT-5.4 Mini measured |
| ALE-Bench | 1188.6 | 1590.1 | Muse Spark Open |
| LMArena Text: coding | 1438 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: software and IT | 1436 | Not measured | Only GPT-5.4 Mini measured |
| LMArena WebDev: React | 1386 | 1529 | Muse Spark Open |
| LMArena WebDev: HTML | 1419 | 1495 | Muse Spark Open |
| Neither model has a result on the other 20 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5.4 Mini | Muse Spark Open | Leader |
|---|---|---|---|
| AA Intelligence Index | 24.1 | Not measured | Only GPT-5.4 Mini measured |
| Epoch Capabilities Index | 148.7 | 155.1 | Muse Spark Open |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index04
| Benchmark | GPT-5.4 Mini | Muse Spark Open | Leader |
|---|---|---|---|
| AA Agentic Index | 17.9 | Not measured | Only GPT-5.4 Mini measured |
| LiveBench research | Not measured | 80.3% | Only Muse Spark Open measured |
| LiveBench browser | Not measured | 36.0% | Only Muse Spark Open measured |
| LiveBench long agentic | Not measured | 18.9% | Only Muse Spark Open measured |
| Finance Agent (Vals AI) | 45.4% | 61.3% | Muse Spark Open |
| Tax Agent Bench (Vals AI) | 8.8% | 26.3% | Muse Spark Open |
| Legal Research Bench (Vals AI) | 12.5% | 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) | 45.4% | 53.7% | Muse Spark Open |
| τ²-Bench Telecom | 83.3% | Not measured | Only GPT-5.4 Mini measured |
| APEX-Agents | Not measured | 33.4% | Only Muse Spark Open measured |
| DeepResearch Bench | 36.3% | Not measured | Only GPT-5.4 Mini measured |
| Neither model has a result on the other 29 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | GPT-5.4 Mini | Muse Spark Open | Leader |
|---|---|---|---|
| GPQA Diamond | 83.1% | Not measured | Only GPT-5.4 Mini measured |
| LiveBench reasoning | Not measured | 73.7% | Only Muse Spark Open measured |
| MMMU Pro (Vals AI) | 79.3% | Not measured | Only GPT-5.4 Mini measured |
| GPQA Diamond (Artificial Analysis run) | 87.5% | 89.0% | Muse Spark Open |
| Humanity's Last Exam (Artificial Analysis run) | 28.1% | 43.9% | Muse Spark Open |
| GPQA Diamond (Epoch AI run) | 86.9% | Not measured | Only GPT-5.4 Mini measured |
| ARC-AGI | 63.7% | Not measured | Only GPT-5.4 Mini measured |
| ARC-AGI-2 | 18.9% | Not measured | Only GPT-5.4 Mini measured |
| Chess puzzles | 23.0% | Not measured | Only GPT-5.4 Mini measured |
| Mystery game puzzles | 11.0% | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: hard prompts | 1424 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: expert | 1435 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: hard prompts in English | 1420 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: diagrams | 1266 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: homework | 1285 | Not measured | Only GPT-5.4 Mini measured |
| Kagi LLM Benchmark | 37.9% | Not measured | Only GPT-5.4 Mini measured |
| Neither model has a result on the other 6 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index7 boards, none shared
| Benchmark | GPT-5.4 Mini | Muse Spark Open | Leader |
|---|---|---|---|
| AIME | 95.6% | Not measured | Only GPT-5.4 Mini measured |
| OTIS Mock AIME | 88.9% | Not measured | Only GPT-5.4 Mini measured |
| FrontierMath, tiers 1 to 3 | 51.2% | Not measured | Only GPT-5.4 Mini measured |
| FrontierMath, tier 4 | 9.8% | Not measured | Only GPT-5.4 Mini measured |
| ProofBench | 21.0% | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: math | 1418 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: mathematical work | 1429 | Not measured | Only GPT-5.4 Mini measured |
| Neither model has a result on the other 6 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index10 boards, none shared
| Benchmark | GPT-5.4 Mini | Muse Spark Open | Leader |
|---|---|---|---|
| MMLU Pro | 84.5% | Not measured | Only GPT-5.4 Mini measured |
| CaseLaw (Vals AI) | 51.7% | Not measured | Only GPT-5.4 Mini measured |
| CorpFin (Vals AI) | 60.9% | Not measured | Only GPT-5.4 Mini measured |
| TaxEval (Vals AI) | 71.2% | Not measured | Only GPT-5.4 Mini measured |
| MortgageTax (Vals AI) | 63.5% | Not measured | Only GPT-5.4 Mini measured |
| SimpleQA Verified | 29.4% | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: science | 1417 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: medicine and healthcare | 1395 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: legal and government | 1414 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: business and finance | 1418 | Not measured | Only GPT-5.4 Mini measured |
| Neither model has a result on the other 8 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index3 boards, none shared
| Benchmark | GPT-5.4 Mini | Muse Spark Open | Leader |
|---|---|---|---|
| Design Arena: websites | Not measured | 1310 | Only Muse Spark Open measured |
| Design Arena: game dev | Not measured | 1282 | Only Muse Spark Open measured |
| LiveBench design | Not measured | 60.3% | Only Muse Spark Open measured |
| Neither model has a result on the other 6 boards here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5.4 Mini | Muse Spark Open | Leader |
|---|---|---|---|
| Vals Index | Not measured | 48.6% | Only Muse Spark Open measured |
| LiveBench data analysis | Not measured | 60.2% | Only Muse Spark Open measured |
| SAGE (Vals AI) | 50.8% | Not measured | Only GPT-5.4 Mini measured |
| Vals Multimodal Index | 54.2% | Not measured | Only GPT-5.4 Mini measured |
| IFBench | 73.3% | Not measured | Only GPT-5.4 Mini measured |
| Long context reasoning (AA-LCR) | 77.0% | 78.3% | Muse Spark Open |
| DTBench | 80.0% | Not measured | Only GPT-5.4 Mini measured |
| LMCA | 40.8% | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text | 1412 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: instruction following | 1405 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: creative writing | 1370 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision | 1245 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: English | 1412 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: non-English | 1405 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: Chinese | 1446 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: German | 1408 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: Japanese | 1375 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: Korean | 1370 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: French | 1441 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: Spanish | 1405 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: Russian | 1417 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: Polish | 1415 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: multi-turn | 1429 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: longer queries | 1408 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: writing and language | 1393 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: entertainment and media | 1373 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: English | 1244 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: Chinese | 1286 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: reading text | 1253 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: humor | 1235 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: recognizing things | 1218 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: creative writing | 1222 | Not measured | Only GPT-5.4 Mini 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
| Benchmark | GPT-5.4 Mini | 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
GPT-5.4 Mini costs less
Repository review
50K input + 3K output tokens
GPT-5.4 Mini costs less
Agent loop
200K input + 10K output tokens
GPT-5.4 Mini 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 | OpenAI GPT-5.4 Mini | Meta Muse Spark Open |
|---|---|---|
| Maker | OpenAI | Meta |
| Weights | No public weights listed | Open weights |
| Released | March 17, 2026 | October 15, 2026 |
| Context window | 400K | 1.05M |
| Input $/Mtok | $0.75 | $1.25 |
| Output $/Mtok | $4.50 | $4.25 |
| Coding index | 35.8 | 47.4 |
| Independent measurements behind it | 5 | 4 |
| Cost per solved task | $0.70 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.4 Mini better than Muse Spark Open for coding?
Pick Muse Spark Open for coding: it scores 47.4 on the Vibe Coding Index against 35.8 for GPT-5.4 Mini, though on 4 benchmarks against 5. GPT-5.4 Mini is neither cheaper nor larger in context, and leads no benchmark both models were measured on.
Which is cheaper, GPT-5.4 Mini or Muse Spark Open?
GPT-5.4 Mini costs $0.75 per million input tokens and $4.50 per million output tokens; Muse Spark Open costs $1.25 and $4.25. Cost per solved task is known for GPT-5.4 Mini only.
Which has the bigger context window, GPT-5.4 Mini or Muse Spark Open?
Muse Spark Open, with 1.05M tokens against 400K.
How many benchmarks is the GPT-5.4 Mini vs Muse Spark Open comparison based on?
16 benchmarks have a result for both models as of October 22, 2026. GPT-5.4 Mini's coding index rests on 5 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.