Ternary Bonsai 2 27B vs Step 5 Preview
Ternary Bonsai 2 27B costs 5.4x less per output token than Step 5 Preview ($0.50 vs $2.70 per million). Updated October 22, 2026; no benchmark has tested both models yet.
- Coding
- No data
- Overall
- No data
- Output $/M
- $0.50
- Coding
- 61.1
- Overall
- 60.5
- Output $/M
- $2.70
Ternary Bonsai 2 27B or Step 5 Preview: which to pick
Only Step 5 Preview has a coding score, 61.1 on the Vibe Coding Index; Ternary Bonsai 2 27B has none, so the two cannot be ranked on coding.
Pick Ternary Bonsai 2 27B for output tokens 5.4x cheaper ($0.50 vs $2.70 per million).
No benchmark has tested both yet. Ternary Bonsai 2 27B has none yet; Step 5 Preview on LiveBench coding, LMArena WebDev and Terminal-Bench 4 (Vals AI). Compare them on price and context instead.
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 Step 5 Preview has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
No call
Only Step 5 Preview has a AA Intelligence Index result, 43.7.
Directional only
Long documents
Listed context window
Step 5 Preview
Step 5 Preview takes 1.05M tokens against 262K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Ternary Bonsai 2 27B
Ternary Bonsai 2 27B $0.0003, Step 5 Preview $0.0024 per turn.
List prices
At a glance
- Coding index
- Ternary Bonsai 2 27B not benchmarked, Step 5 Preview 61.1 from 4 benchmarks.
- Widest category
- None yet: no category has been tested on both models.
- Widest single gap
- None yet: no benchmark has tested both models.
- Output price
- Ternary Bonsai 2 27B $0.50 against Step 5 Preview $2.70 per million output tokens, 5.4x apart.
- Context window
- Ternary Bonsai 2 27B takes 262K tokens, Step 5 Preview 1.05M.
Benchmark by benchmark
Every board either model has a result on, a category to a fold; bars are each result on a 0 to 100 scale. Only one model is measured on each, so no row names a leader.
CodingDirectional onlySix of these boards feed the Vibe Coding Index13 boards measured
| Benchmark | Ternary Bonsai 2 27B | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench coding | Not measured | 85.6% | Only Step 5 Preview measured |
| LMArena WebDev | Not measured | 1567 | Only Step 5 Preview measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 31.8% | Only Step 5 Preview measured |
| Vibe Code Bench (Vals AI) | Not measured | 70.4% | Only Step 5 Preview measured |
| 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 |
| LMArena Text: coding | Not measured | 1485 | Only Step 5 Preview measured |
| LMArena Text: software and IT | Not measured | 1473 | Only Step 5 Preview measured |
| LMArena WebDev: React | Not measured | 1583 | Only Step 5 Preview measured |
| LMArena WebDev: HTML | Not measured | 1556 | Only Step 5 Preview measured |
| LMArena WebDev: from an image | Not measured | 1550 | Only Step 5 Preview measured |
| Neither model has a result on the other 26 boards here | |||
IntelligenceDirectional onlyPublic boards, shown as published, kept out of the index1 board measured
| Benchmark | Ternary Bonsai 2 27B | Step 5 Preview | Leader |
|---|---|---|---|
| AA Intelligence Index | Not measured | 43.7 | Only Step 5 Preview measured |
| Neither model has a result on the other 1 board here | |||
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index11 boards measured
| Benchmark | Ternary Bonsai 2 27B | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench research | Not measured | 72.8% | Only Step 5 Preview measured |
| LiveBench browser | Not measured | 24.0% | Only Step 5 Preview measured |
| LiveBench long agentic | Not measured | 27.5% | 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) | Not measured | 27.3% | Only Step 5 Preview measured |
| Legal Research Bench (Vals AI) | Not measured | 40.4% | Only Step 5 Preview measured |
| 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 |
| Neither model has a result on the other 30 boards here | |||
ReasoningDirectional onlyPublic boards, shown as published, kept out of the index8 boards measured
| Benchmark | Ternary Bonsai 2 27B | 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 |
| LMArena Text: hard prompts | Not measured | 1461 | Only Step 5 Preview measured |
| LMArena Text: expert | Not measured | 1485 | Only Step 5 Preview measured |
| LMArena Text: hard prompts in English | Not measured | 1454 | Only Step 5 Preview measured |
| LMArena Vision: diagrams | Not measured | 1308 | Only Step 5 Preview measured |
| LMArena Vision: homework | Not measured | 1265 | Only Step 5 Preview measured |
| Neither model has a result on the other 14 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index3 boards measured
| Benchmark | Ternary Bonsai 2 27B | Step 5 Preview | Leader |
|---|---|---|---|
| ProofBench | Not measured | 42.0% | Only Step 5 Preview measured |
| LMArena Text: math | Not measured | 1458 | Only Step 5 Preview measured |
| LMArena Text: mathematical work | Not measured | 1460 | Only Step 5 Preview measured |
| Neither model has a result on the other 10 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index4 boards measured
| Benchmark | Ternary Bonsai 2 27B | Step 5 Preview | Leader |
|---|---|---|---|
| LMArena Text: science | Not measured | 1454 | Only Step 5 Preview measured |
| LMArena Text: medicine and healthcare | Not measured | 1439 | Only Step 5 Preview measured |
| LMArena Text: legal and government | Not measured | 1437 | Only Step 5 Preview measured |
| LMArena Text: business and finance | Not measured | 1435 | Only Step 5 Preview measured |
| Neither model has a result on the other 14 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index1 board measured
| Benchmark | Ternary Bonsai 2 27B | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench design | Not measured | 76.9% | Only Step 5 Preview measured |
| Neither model has a result on the other 8 boards here | |||
GeneralDirectional onlyPublic boards, shown as published, kept out of the index20 boards measured
| Benchmark | Ternary Bonsai 2 27B | Step 5 Preview | Leader |
|---|---|---|---|
| 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 |
| LMArena Text | Not measured | 1440 | Only Step 5 Preview measured |
| LMArena Text: instruction following | Not measured | 1438 | Only Step 5 Preview measured |
| LMArena Text: creative writing | Not measured | 1409 | Only Step 5 Preview measured |
| LMArena Vision | Not measured | 1265 | Only Step 5 Preview measured |
| LMArena Text: English | Not measured | 1447 | Only Step 5 Preview measured |
| LMArena Text: non-English | Not measured | 1428 | Only Step 5 Preview measured |
| LMArena Text: Chinese | Not measured | 1500 | Only Step 5 Preview measured |
| LMArena Text: Japanese | Not measured | 1383 | Only Step 5 Preview measured |
| LMArena Text: French | Not measured | 1438 | Only Step 5 Preview measured |
| LMArena Text: Spanish | Not measured | 1441 | Only Step 5 Preview measured |
| LMArena Text: Russian | Not measured | 1433 | Only Step 5 Preview measured |
| LMArena Text: multi-turn | Not measured | 1437 | Only Step 5 Preview measured |
| LMArena Text: longer queries | Not measured | 1449 | Only Step 5 Preview measured |
| LMArena Text: writing and language | Not measured | 1425 | Only Step 5 Preview measured |
| LMArena Text: entertainment and media | Not measured | 1412 | Only Step 5 Preview measured |
| LMArena Vision: English | Not measured | 1290 | Only Step 5 Preview measured |
| LMArena Vision: reading text | Not measured | 1282 | Only Step 5 Preview measured |
| Neither model has a result on the other 26 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
Ternary Bonsai 2 27B costs less
Repository review
50K input + 3K output tokens
Ternary Bonsai 2 27B costs less
Agent loop
200K input + 10K output tokens
Ternary Bonsai 2 27B 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 | PrismML Ternary Bonsai 2 27B | StepFun Step 5 Preview |
|---|---|---|
| Maker | Prism-ml | StepFun |
| Weights | Open weights | Open weights |
| Released | September 18, 2026 | October 8, 2026 |
| Context window | 262K | 1.05M |
| Input $/Mtok | $0.075 | $1.00 |
| Output $/Mtok | $0.50 | $2.70 |
| Coding index | Not benchmarked | 61.1 |
| Independent measurements behind it | 0 | 4 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Ternary Bonsai 2 27B better than Step 5 Preview for coding?
Only Step 5 Preview has a coding score, 61.1 on the Vibe Coding Index; Ternary Bonsai 2 27B has none, so the two cannot be ranked on coding. Pick Ternary Bonsai 2 27B for output tokens 5.4x cheaper ($0.50 vs $2.70 per million).
Which is cheaper, Ternary Bonsai 2 27B or Step 5 Preview?
Ternary Bonsai 2 27B costs $0.075 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, Ternary Bonsai 2 27B or Step 5 Preview?
Step 5 Preview, with 1.05M tokens against 262K.
Has any benchmark tested both Ternary Bonsai 2 27B and Step 5 Preview?
No benchmark has tested both yet. Ternary Bonsai 2 27B has none yet; Step 5 Preview on LiveBench coding, LMArena WebDev and Terminal-Bench 4 (Vals AI). Compare them on price and context instead. Data as of October 22, 2026.