gpt-oss-20b vs Muse Spark 1.2
Muse Spark 1.2 leads gpt-oss-20b on the Artificial Analysis Intelligence Index, 39.6 to 10.0, and gpt-oss-20b costs 28.3x less per output token ($0.15 vs $4.25 per million). Updated October 22, 2026; 39 benchmarks have a result for both.
gpt-oss-20b or Muse Spark 1.2: which to pick
Only Muse Spark 1.2 has a coding score, 55.7 on the Vibe Coding Index; gpt-oss-20b has none, so the two cannot be ranked on coding.
Pick gpt-oss-20b for output tokens 28.3x cheaper ($0.15 vs $4.25 per million).
- Shared results
- 39
- gpt-oss-20b only
- 23
- Muse Spark 1.2 only
- 58
- Like-for-like categories
- 7 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
No call
Only Muse Spark 1.2 has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
Muse Spark 1.2
Muse Spark 1.2 leads, 39.6 against 10.0.
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
Reasoning
GPQA Diamond
No call
Only gpt-oss-20b has a GPQA Diamond result, 68.9%.
Directional only
Math
AIME
No call
Only gpt-oss-20b has a AIME result, 86.0%.
Directional only
Knowledge
MMLU Pro
Muse Spark 1.2
Muse Spark 1.2 leads, 88.3% against 71.6%.
Same board, both measured
Web design
Design Arena: websites
Muse Spark 1.2
Muse Spark 1.2 leads, 1312 against 852.
Same board, both measured
Long documents
Listed context window
Muse Spark 1.2
Muse Spark 1.2 takes 1.05M tokens against 131K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
gpt-oss-20b
gpt-oss-20b $0.0001, 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
- gpt-oss-20b not benchmarked, Muse Spark 1.2 55.7 from 5 benchmarks.
- Widest category
- Web design, 53.8 points apart on average over 2 shared benchmarks.
- Widest single gap
- Design Arena: websites: gpt-oss-20b 852 against Muse Spark 1.2 1312, 57.5 points apart on a 0 to 100 scale.
- Output price
- gpt-oss-20b $0.15 against Muse Spark 1.2 $4.25 per million output tokens, 28.3x apart.
- Context window
- gpt-oss-20b takes 131K 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 | gpt-oss-20b | Bars | Muse Spark 1.2 | Ties |
|---|---|---|---|---|
| Coding | 0 | 4 | ||
| Intelligence | 0 | 2 | ||
| Reasoning | 0 | 5 | ||
| Math | 0 | 2 | ||
| Knowledge | 0 | 8 | ||
| Web design | 0 | 2 | ||
| General | 0 | 16 | ||
| All shared boards | 0 | 39 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index04
| Benchmark | gpt-oss-20b | Muse Spark 1.2 | Leader |
|---|---|---|---|
| LiveBench coding | Not measured | 78.2% | Only Muse Spark 1.2 measured |
| LMArena WebDev | Not measured | 1534 | Only Muse Spark 1.2 measured |
| AA Coding Index | Not measured | 72.2 | Only Muse Spark 1.2 measured |
| LiveCodeBench (Vals AI) | 80.4% | Not measured | Only gpt-oss-20b measured |
| SWE-bench Verified (Vals AI) | Not measured | 86.6% | Only Muse Spark 1.2 measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 6.1% | Only Muse Spark 1.2 measured |
| Vibe Code Bench (Vals AI) | Not measured | 79.1% | Only Muse Spark 1.2 measured |
| Code migration (Vals AI) | Not measured | 29.9% | Only Muse Spark 1.2 measured |
| ProgramBench (Vals AI) | Not measured | 0.5% | Only Muse Spark 1.2 measured |
| IOI (Vals AI) | Not measured | 21.8% | Only Muse Spark 1.2 measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 69.7% | Only Muse Spark 1.2 measured |
| SkillsBench (Vals AI) | Not measured | 53.0% | Only Muse Spark 1.2 measured |
| CyberBench (Vals AI) | Not measured | 69.5% | Only Muse Spark 1.2 measured |
| LiveCodeBench (Artificial Analysis run) | 77.7% | Not measured | Only gpt-oss-20b measured |
| SciCode | 38.9% | 57.4% | Muse Spark 1.2 |
| Terminal-Bench Hard (Artificial Analysis run) | 10.6% | Not measured | Only gpt-oss-20b measured |
| Terminal-Bench | 3.4% | Not measured | Only gpt-oss-20b measured |
| FrontierSWE | Not measured | 12.0% | Only Muse Spark 1.2 measured |
| WeirdML | 40.9% | 60.3% | Muse Spark 1.2 |
| ALE-Bench | 566.0 | Not measured | Only gpt-oss-20b measured |
| LMArena Text: coding | 1307 | 1505 | Muse Spark 1.2 |
| LMArena Text: software and IT | 1311 | 1505 | Muse Spark 1.2 |
| LMArena WebDev: React | Not measured | 1526 | Only Muse Spark 1.2 measured |
| LMArena WebDev: HTML | Not measured | 1543 | Only Muse Spark 1.2 measured |
| Neither model has a result on the other 15 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | gpt-oss-20b | Muse Spark 1.2 | Leader |
|---|---|---|---|
| AA Intelligence Index | 10.0 | 39.6 | Muse Spark 1.2 |
| Epoch Capabilities Index | 137.7 | 155.1 | Muse Spark 1.2 |
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index20 boards, none shared
| Benchmark | gpt-oss-20b | Muse Spark 1.2 | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 43.2 | Only Muse Spark 1.2 measured |
| Design Arena: agents building web apps | Not measured | 1221 | Only Muse Spark 1.2 measured |
| Design Arena: agents building full-stack apps | Not measured | 1210 | Only Muse Spark 1.2 measured |
| Design Arena: agents building mobile apps | Not measured | 1181 | Only Muse Spark 1.2 measured |
| 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 |
| LiveBench research | Not measured | 67.7% | Only Muse Spark 1.2 measured |
| LiveBench browser | Not measured | 36.0% | Only Muse Spark 1.2 measured |
| LiveBench long agentic | Not measured | 21.3% | Only Muse Spark 1.2 measured |
| SREBench (Vals AI) | Not measured | 0.0% | Only Muse Spark 1.2 measured |
| Finance Agent (Vals AI) | Not measured | 60.6% | Only Muse Spark 1.2 measured |
| Tax Agent Bench (Vals AI) | Not measured | 32.8% | Only Muse Spark 1.2 measured |
| Legal Research Bench (Vals AI) | Not measured | 43.8% | Only Muse Spark 1.2 measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 57.0% | Only Muse Spark 1.2 measured |
| BioMysteryBench (Vals AI) | Not measured | 64.8% | Only Muse Spark 1.2 measured |
| τ²-Bench Telecom | 60.2% | Not measured | Only gpt-oss-20b measured |
| APEX-Agents | Not measured | 45.4% | Only Muse Spark 1.2 measured |
| BrowseComp-Plus | 50.6% | Not measured | Only gpt-oss-20b measured |
| Neither model has a result on the other 21 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index05
| Benchmark | gpt-oss-20b | Muse Spark 1.2 | Leader |
|---|---|---|---|
| GPQA Diamond | 68.9% | Not measured | Only gpt-oss-20b measured |
| LiveBench reasoning | Not measured | 90.0% | Only Muse Spark 1.2 measured |
| MMMU Pro (Vals AI) | Not measured | 86.1% | Only Muse Spark 1.2 measured |
| GPQA Diamond (Artificial Analysis run) | 68.8% | 90.4% | Muse Spark 1.2 |
| Humanity's Last Exam (Artificial Analysis run) | 11.0% | 45.5% | Muse Spark 1.2 |
| GPQA Diamond (Epoch AI run) | 60.8% | Not measured | Only gpt-oss-20b measured |
| SimpleBench | Not measured | 74.5% | Only Muse Spark 1.2 measured |
| Chess puzzles | Not measured | 27.0% | Only Muse Spark 1.2 measured |
| LMArena Text: hard prompts | 1274 | 1489 | Muse Spark 1.2 |
| LMArena Text: expert | 1258 | 1475 | Muse Spark 1.2 |
| LMArena Text: hard prompts in English | 1292 | 1487 | Muse Spark 1.2 |
| LMArena Vision: diagrams | Not measured | 1317 | Only Muse Spark 1.2 measured |
| Kagi LLM Benchmark | 53.2% | Not measured | Only gpt-oss-20b measured |
| Neither model has a result on the other 9 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | gpt-oss-20b | Muse Spark 1.2 | Leader |
|---|---|---|---|
| AIME | 86.0% | Not measured | Only gpt-oss-20b measured |
| MATH 500 (Vals AI) | 94.2% | Not measured | Only gpt-oss-20b measured |
| MGSM (Vals AI) | 89.0% | Not measured | Only gpt-oss-20b measured |
| AA Math Index | 89.3 | Not measured | Only gpt-oss-20b measured |
| AIME 2025 (Artificial Analysis run) | 89.3% | Not measured | Only gpt-oss-20b measured |
| OTIS Mock AIME | 65.3% | Not measured | Only gpt-oss-20b measured |
| ProofBench | Not measured | 43.0% | Only Muse Spark 1.2 measured |
| LMArena Text: math | 1317 | 1484 | Muse Spark 1.2 |
| LMArena Text: mathematical work | 1305 | 1480 | Muse Spark 1.2 |
| Neither model has a result on the other 4 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index08
| Benchmark | gpt-oss-20b | Muse Spark 1.2 | Leader |
|---|---|---|---|
| MMLU Pro | 71.6% | 88.3% | Muse Spark 1.2 |
| LegalBench (Vals AI) | 70.8% | 85.3% | Muse Spark 1.2 |
| CaseLaw (Vals AI) | 43.8% | Not measured | Only gpt-oss-20b measured |
| CorpFin (Vals AI) | 53.1% | 70.9% | Muse Spark 1.2 |
| TaxEval (Vals AI) | 63.7% | 80.4% | Muse Spark 1.2 |
| MortgageTax (Vals AI) | Not measured | 65.4% | Only Muse Spark 1.2 measured |
| MedQA (Vals AI) | 82.9% | Not measured | Only gpt-oss-20b measured |
| MedCode (Vals AI) | Not measured | 49.4% | Only Muse Spark 1.2 measured |
| MMLU Pro (Artificial Analysis run) | 74.8% | Not measured | Only gpt-oss-20b measured |
| SimpleQA Verified | Not measured | 60.3% | Only Muse Spark 1.2 measured |
| LMArena Text: science | 1296 | 1500 | Muse Spark 1.2 |
| LMArena Text: medicine and healthcare | 1310 | 1496 | Muse Spark 1.2 |
| LMArena Text: legal and government | 1280 | 1517 | Muse Spark 1.2 |
| LMArena Text: business and finance | 1284 | 1484 | Muse Spark 1.2 |
| Neither model has a result on the other 4 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | gpt-oss-20b | Muse Spark 1.2 | Leader |
|---|---|---|---|
| Design Arena: websites | 852 | 1312 | Muse Spark 1.2 |
| Design Arena: UI components | Not measured | 1298 | Only Muse Spark 1.2 measured |
| Design Arena: game dev | Not measured | 1301 | Only Muse Spark 1.2 measured |
| Design Arena: data viz | 933 | 1334 | Muse Spark 1.2 |
| Design Arena: 3D | Not measured | 1301 | Only Muse Spark 1.2 measured |
| Design Arena: all code categories | Not measured | 1312 | Only Muse Spark 1.2 measured |
| Design Arena: SVG | Not measured | 1284 | Only Muse Spark 1.2 measured |
| Design Arena: ASCII art | Not measured | 1284 | Only Muse Spark 1.2 measured |
| LiveBench design | Not measured | 67.1% | Only Muse Spark 1.2 measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index016
| Benchmark | gpt-oss-20b | Muse Spark 1.2 | Leader |
|---|---|---|---|
| LiveBench data analysis | Not measured | 76.5% | Only Muse Spark 1.2 measured |
| Public Benefits Bench (Vals AI) | Not measured | 68.5% | Only Muse Spark 1.2 measured |
| SAGE (Vals AI) | Not measured | 47.7% | Only Muse Spark 1.2 measured |
| MedScribe (Vals AI) | Not measured | 90.1% | Only Muse Spark 1.2 measured |
| Vals Multimodal Index | Not measured | 69.8% | Only Muse Spark 1.2 measured |
| IFBench | 65.1% | Not measured | Only gpt-oss-20b measured |
| Long context reasoning (AA-LCR) | 34.7% | 79.0% | Muse Spark 1.2 |
| DTBench | 68.0% | 94.7% | Muse Spark 1.2 |
| LMCA | 14.5% | 48.4% | Muse Spark 1.2 |
| LMArena Text | 1288 | 1482 | Muse Spark 1.2 |
| LMArena Text: instruction following | 1236 | 1462 | Muse Spark 1.2 |
| LMArena Text: creative writing | 1201 | 1436 | Muse Spark 1.2 |
| LMArena Vision | Not measured | 1304 | Only Muse Spark 1.2 measured |
| LMArena Text: English | 1303 | 1483 | Muse Spark 1.2 |
| LMArena Text: non-English | 1269 | 1476 | Muse Spark 1.2 |
| LMArena Text: Chinese | 1315 | 1509 | Muse Spark 1.2 |
| LMArena Text: German | 1255 | Not measured | Only gpt-oss-20b measured |
| LMArena Text: Japanese | 1244 | Not measured | Only gpt-oss-20b measured |
| LMArena Text: Korean | 1236 | 1462 | Muse Spark 1.2 |
| LMArena Text: French | Not measured | 1495 | Only Muse Spark 1.2 measured |
| LMArena Text: Spanish | 1267 | 1484 | Muse Spark 1.2 |
| LMArena Text: Russian | 1278 | 1483 | Muse Spark 1.2 |
| LMArena Text: Polish | 1252 | Not measured | Only gpt-oss-20b measured |
| LMArena Text: multi-turn | 1268 | 1502 | Muse Spark 1.2 |
| LMArena Text: longer queries | 1250 | 1473 | Muse Spark 1.2 |
| LMArena Text: writing and language | 1238 | 1453 | Muse Spark 1.2 |
| LMArena Text: entertainment and media | 1216 | 1443 | Muse Spark 1.2 |
| LMArena Vision: English | Not measured | 1291 | Only Muse Spark 1.2 measured |
| LMArena Vision: reading text | Not measured | 1313 | Only Muse Spark 1.2 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 | gpt-oss-20b | 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
gpt-oss-20b costs less
Repository review
50K input + 3K output tokens
gpt-oss-20b costs less
Agent loop
200K input + 10K output tokens
gpt-oss-20b 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-oss-20b | Meta Muse Spark 1.2 |
|---|---|---|
| Maker | OpenAI | Meta |
| Weights | Open weights | No public weights listed |
| Released | August 5, 2025 | August 5, 2026 |
| Context window | 131K | 1.05M |
| Input $/Mtok | $0.03 | $1.25 |
| Output $/Mtok | $0.15 | $4.25 |
| Coding index | Not benchmarked | 55.7 |
| Independent measurements behind it | 0 | 5 |
| Cost per solved task | Not computable | $0.64 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is gpt-oss-20b better than Muse Spark 1.2 for coding?
Only Muse Spark 1.2 has a coding score, 55.7 on the Vibe Coding Index; gpt-oss-20b has none, so the two cannot be ranked on coding. Pick gpt-oss-20b for output tokens 28.3x cheaper ($0.15 vs $4.25 per million).
Which is cheaper, gpt-oss-20b or Muse Spark 1.2?
gpt-oss-20b costs $0.03 per million input tokens and $0.15 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, gpt-oss-20b or Muse Spark 1.2?
Muse Spark 1.2, with 1.05M tokens against 131K.
How many benchmarks is the gpt-oss-20b vs Muse Spark 1.2 comparison based on?
39 benchmarks have a result for both models as of October 22, 2026. gpt-oss-20b's coding index rests on 0 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.