Muse Ember vs Step 5 Preview
Muse Ember leads Step 5 Preview on coding, 64.9 to 57.4 on the Vibe Coding Index, and Muse Ember costs 5.4x less per output token ($0.50 vs $2.70 per million). Updated November 14, 2026; 14 benchmarks have a result for both.
Muse Ember or Step 5 Preview: which to pick
Pick Muse Ember for coding: it scores 64.9 on the Vibe Coding Index against 57.4 for Step 5 Preview, though on 3 benchmarks against 4.
Pick Step 5 Preview for work measured by AA-Omniscience, where it leads.
- Shared results
- 14
- Muse Ember only
- 1
- Step 5 Preview only
- 61
- 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 Ember
Muse Ember scores 64.9 against 57.4.
3 and 4 benchmarks behind the scores
Intelligence
AA Intelligence Index
No call
Only Step 5 Preview has a AA Intelligence Index result, 28.5.
Directional only
General
Vals Index
Muse Ember
Muse Ember leads, 60.5% against 54.8%.
Same board, both measured
Long documents
Listed context window
Muse Ember
Muse Ember takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Muse Ember
Muse Ember $0.0003, Step 5 Preview $0.0024 per turn.
List prices
At a glance
- Coding index
- Muse Ember 64.9 from 3 benchmarks, Step 5 Preview 57.4 from 4 benchmarks.
- Widest category
- Agentic work, 10.6 points apart on average over 3 shared benchmarks.
- Widest single gap
- FrontierCode 2.0: Muse Ember 27.2% against Step 5 Preview 12.0%, 15.2 points apart on a 0 to 100 scale.
- Output price
- Muse Ember $0.50 against Step 5 Preview $2.70 per million output tokens, 5.4x apart.
- Context window
- Muse Ember takes 1.05M tokens, Step 5 Preview 1M.
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 | Muse Ember | Bars | Step 5 Preview | Ties |
|---|---|---|---|---|
| Coding | 7 | 0 | ||
| Agentic work | 3 | 0 | ||
| Reasoning | 2 | 0 | ||
| Knowledge | 0 | 1 | ||
| General | 1 | 0 | ||
| All shared boards | 13 | 1 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index70
| Benchmark | Muse Ember | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench coding | Not measured | 67.6% | Only Step 5 Preview measured |
| LMArena WebDev | 1609 | 1573 | Muse Ember |
| Terminal-Bench 4 (Vals AI) | 39.4% | 31.8% | Muse Ember |
| Vibe Code Bench (Vals AI) | 83.7% | 70.4% | Muse Ember |
| Code migration (Vals AI) | Not measured | 39.0% | Only Step 5 Preview measured |
| IOI (Vals AI) | Not measured | 38.1% | Only Step 5 Preview measured |
| SWE-bench Multimodal (Vals AI) | Not measured | 40.8% | Only Step 5 Preview measured |
| SciCode | Not measured | 58.9% | Only Step 5 Preview measured |
| Terminal-Bench 4.0 (Artificial Analysis run) | 40.9% | 33.3% | Muse Ember |
| FrontierCode 2.0 | 27.2% | 12.0% | Muse Ember |
| LMArena Text: coding | Not measured | 1482 | Only Step 5 Preview measured |
| LMArena Text: software and IT | Not measured | 1471 | Only Step 5 Preview measured |
| LMArena WebDev: React | 1616 | 1589 | Muse Ember |
| LMArena WebDev: HTML | 1621 | 1546 | Muse Ember |
| LMArena WebDev: from an image | Not measured | 1551 | Only Step 5 Preview measured |
| GameBench 2 | Not measured | 52.6 | Only Step 5 Preview measured |
| Neither model has a result on the other 36 boards here | |||
IntelligenceDirectional onlyPublic boards, shown as published, kept out of the index1 board, none shared
| Benchmark | Muse Ember | Step 5 Preview | Leader |
|---|---|---|---|
| AA Intelligence Index | Not measured | 28.5 | Only Step 5 Preview measured |
| Neither model has a result on the other 1 board here | |||
Agentic workLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Muse Ember | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench research | Not measured | 75.5% | Only Step 5 Preview measured |
| LiveBench browser | Not measured | 24.8% | Only Step 5 Preview measured |
| LiveBench long agentic | Not measured | 19.4% | Only Step 5 Preview measured |
| SREBench (Vals AI) | Not measured | 0.4% | Only Step 5 Preview measured |
| Finance Agent (Vals AI) | Not measured | 50.7% | Only Step 5 Preview measured |
| Tax Agent Bench (Vals AI) | 38.2% | 27.3% | Muse Ember |
| Legal Research Bench (Vals AI) | 49.0% | 40.4% | Muse Ember |
| Harvey's Legal Agent Benchmark (Vals AI) | 25.0% | 12.9% | Muse Ember |
| Excel Modeling Benchmark (Vals AI) | Not measured | 57.1% | Only Step 5 Preview measured |
| BioMysteryBench (Vals AI) | Not measured | 67.4% | Only Step 5 Preview measured |
| Terminal-Bench-Science (Vals AI) | Not measured | 2.9% | Only Step 5 Preview measured |
| Vals Science Index | Not measured | 29.6% | Only Step 5 Preview measured |
| APEX-Agents | 64.3% | Not measured | Only Muse Ember measured |
| Neither model has a result on the other 31 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Muse Ember | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench reasoning | Not measured | 83.8% | Only Step 5 Preview measured |
| MysteryMechanism (Vals AI) | Not measured | 18.5% | Only Step 5 Preview measured |
| Humanity's Last Exam (Artificial Analysis run) | Not measured | 46.5% | Only Step 5 Preview measured |
| HLE-Diamond (Artificial Analysis run) | 25.1% | 24.3% | Muse Ember |
| CritPt v2, hard subset (Artificial Analysis run) | 39.0% | 32.5% | Muse Ember |
| LMArena Text: hard prompts | Not measured | 1463 | Only Step 5 Preview measured |
| LMArena Text: expert | Not measured | 1478 | Only Step 5 Preview measured |
| LMArena Text: hard prompts in English | Not measured | 1463 | Only Step 5 Preview measured |
| LMArena Vision: diagrams | Not measured | 1295 | Only Step 5 Preview measured |
| LMArena Vision: homework | Not measured | 1274 | Only Step 5 Preview measured |
| Neither model has a result on the other 16 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index3 boards, none shared
| Benchmark | Muse Ember | Step 5 Preview | Leader |
|---|---|---|---|
| ProofBench | Not measured | 42.0% | Only Step 5 Preview measured |
| LMArena Text: math | Not measured | 1462 | Only Step 5 Preview measured |
| LMArena Text: mathematical work | Not measured | 1465 | Only Step 5 Preview measured |
| Neither model has a result on the other 11 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Muse Ember | Step 5 Preview | Leader |
|---|---|---|---|
| AA-Omniscience | 7.7 | 16.4 | Step 5 Preview |
| LMArena Text: science | Not measured | 1462 | Only Step 5 Preview measured |
| LMArena Text: medicine and healthcare | Not measured | 1441 | Only Step 5 Preview measured |
| LMArena Text: legal and government | Not measured | 1441 | Only Step 5 Preview measured |
| LMArena Text: business and finance | Not measured | 1444 | Only Step 5 Preview measured |
| Neither model has a result on the other 16 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index1 board, none shared
| Benchmark | Muse Ember | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench design | Not measured | 70.8% | Only Step 5 Preview measured |
| Neither model has a result on the other 8 boards here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Muse Ember | Step 5 Preview | Leader |
|---|---|---|---|
| Vals Index | 60.5% | 54.8% | Muse Ember |
| LiveBench data analysis | Not measured | 63.5% | Only Step 5 Preview measured |
| Public Benefits Bench (Vals AI) | Not measured | 58.1% | Only Step 5 Preview measured |
| Long context reasoning (AA-LCR) | Not measured | 88.3% | Only Step 5 Preview measured |
| GDPval-AA | Not measured | 1591 | Only Step 5 Preview measured |
| LMArena Text | Not measured | 1443 | Only Step 5 Preview measured |
| LMArena Text: instruction following | Not measured | 1445 | Only Step 5 Preview measured |
| LMArena Text: creative writing | Not measured | 1415 | Only Step 5 Preview measured |
| LMArena Vision | Not measured | 1263 | Only Step 5 Preview measured |
| LMArena Text: English | Not measured | 1455 | Only Step 5 Preview measured |
| LMArena Text: non-English | Not measured | 1429 | Only Step 5 Preview measured |
| LMArena Text: Chinese | Not measured | 1495 | Only Step 5 Preview measured |
| LMArena Text: German | Not measured | 1454 | Only Step 5 Preview measured |
| LMArena Text: Japanese | Not measured | 1397 | Only Step 5 Preview measured |
| LMArena Text: Korean | Not measured | 1404 | Only Step 5 Preview measured |
| LMArena Text: French | Not measured | 1446 | Only Step 5 Preview measured |
| LMArena Text: Spanish | Not measured | 1442 | Only Step 5 Preview measured |
| LMArena Text: Russian | Not measured | 1433 | Only Step 5 Preview measured |
| LMArena Text: Polish | Not measured | 1405 | Only Step 5 Preview measured |
| LMArena Text: multi-turn | Not measured | 1440 | Only Step 5 Preview measured |
| LMArena Text: longer queries | Not measured | 1453 | Only Step 5 Preview measured |
| LMArena Text: writing and language | Not measured | 1429 | Only Step 5 Preview measured |
| LMArena Text: entertainment and media | Not measured | 1413 | Only Step 5 Preview measured |
| LMArena Vision: English | Not measured | 1279 | Only Step 5 Preview measured |
| LMArena Vision: Chinese | Not measured | 1315 | Only Step 5 Preview measured |
| LMArena Vision: reading text | Not measured | 1278 | Only Step 5 Preview measured |
| LMArena Vision: creative writing | Not measured | 1251 | Only Step 5 Preview measured |
| Neither model has a result on the other 22 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Muse Ember | Step 5 Preview | 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 Ember costs less
Repository review
50K input + 3K output tokens
Muse Ember costs less
Agent loop
200K input + 10K output tokens
Muse Ember 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 | Meta Muse Ember | StepFun Step 5 Preview |
|---|---|---|
| Maker | Meta | StepFun |
| Weights | No public weights listed | Open weights |
| Released | November 9, 2026 | October 8, 2026 |
| Context window | 1.05M | 1M |
| Input $/Mtok | $0.10 | $1.00 |
| Output $/Mtok | $0.50 | $2.70 |
| Coding index | 64.9 | 57.4 |
| Independent measurements behind it | 3 | 4 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Muse Ember better than Step 5 Preview for coding?
Pick Muse Ember for coding: it scores 64.9 on the Vibe Coding Index against 57.4 for Step 5 Preview, though on 3 benchmarks against 4. Pick Step 5 Preview for work measured by AA-Omniscience, where it leads.
Which is cheaper, Muse Ember or Step 5 Preview?
Muse Ember costs $0.10 per million input tokens and $0.50 per million output tokens; Step 5 Preview costs $1.00 and $2.70. Cost per solved task is known for neither of them.
Which has the bigger context window, Muse Ember or Step 5 Preview?
Muse Ember, with 1.05M tokens against 1M.
How many benchmarks is the Muse Ember vs Step 5 Preview comparison based on?
14 benchmarks have a result for both models as of November 14, 2026. Muse Ember's coding index rests on 3 independent benchmarks and Step 5 Preview's on 4. Where only one model has a result, the page says so instead of naming a winner.