Kimi K3.1 Pro vs Step 5 Preview
Kimi K3.1 Pro leads Step 5 Preview on coding, 82.2 to 61.2 on the Vibe Coding Index, and Step 5 Preview costs 3.7x less per output token ($2.70 vs $10.00 per million). Updated October 29, 2026; 24 benchmarks have a result for both.
Kimi K3.1 Pro or Step 5 Preview: which to pick
Pick Kimi K3.1 Pro for coding: it scores 82.2 on the Vibe Coding Index against 61.2 for Step 5 Preview.
Pick Step 5 Preview for output tokens 3.7x cheaper ($2.70 vs $10.00 per million) and work measured by LiveBench coding or Tax Agent Bench (Vals AI), where it leads.
- Shared results
- 24
- Kimi K3.1 Pro only
- 11
- Step 5 Preview only
- 40
- 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
Kimi K3.1 Pro
Kimi K3.1 Pro scores 82.2 against 61.2.
4 benchmarks behind each score
Intelligence
AA Intelligence Index
Kimi K3.1 Pro
Kimi K3.1 Pro leads, 46.0 against 28.5.
Same board, both measured
Web design
Design Arena: websites
No call
Only Kimi K3.1 Pro has a Design Arena: websites result, 1325.
Directional only
General
Vals Index
No call
Only Kimi K3.1 Pro has a Vals Index result, 62.5%.
Directional only
Long documents
Listed context window
No call
Both take 1.05M tokens.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Step 5 Preview
Kimi K3.1 Pro $0.0070, Step 5 Preview $0.0024 per turn.
List prices
At a glance
- Coding index
- Kimi K3.1 Pro 82.2 from 4 benchmarks, Step 5 Preview 61.2 from 4 benchmarks.
- Widest category
- Math, 49.0 points apart on average over 1 shared benchmark.
- Widest single gap
- LiveBench browser: Kimi K3.1 Pro 75.9% against Step 5 Preview 24.8%, 51.1 points apart on a 0 to 100 scale.
- Output price
- Kimi K3.1 Pro $10.00 against Step 5 Preview $2.70 per million output tokens, 3.7x apart.
- Context window
- Both take 1.05M tokens.
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 | Kimi K3.1 Pro | Bars | Step 5 Preview | Ties |
|---|---|---|---|---|
| Coding | 7 | 1 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 6 | 2 | ||
| Reasoning | 3 | 0 | ||
| Math | 1 | 0 | ||
| Web design | 1 | 0 | ||
| General | 1 | 1 | ||
| All shared boards | 20 | 4 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index71
| Benchmark | Kimi K3.1 Pro | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench coding | 81.8% | 85.6% | Step 5 Preview |
| LMArena WebDev | 1695 | 1571 | Kimi K3.1 Pro |
| Terminal-Bench 4 (Vals AI) | 63.6% | 31.8% | Kimi K3.1 Pro |
| Vibe Code Bench (Vals AI) | 84.9% | 70.4% | Kimi K3.1 Pro |
| Code migration (Vals AI) | Not measured | 39.0% | Only Step 5 Preview measured |
| IOI (Vals AI) | 81.9% | 38.1% | Kimi K3.1 Pro |
| SWE-bench Multimodal (Vals AI) | Not measured | 40.8% | Only Step 5 Preview measured |
| SciCode | 60.8% | 58.9% | Kimi K3.1 Pro |
| ALE-Bench | 1932.8 | Not measured | Only Kimi K3.1 Pro measured |
| LMArena Text: coding | Not measured | 1482 | Only Step 5 Preview measured |
| LMArena Text: software and IT | Not measured | 1472 | Only Step 5 Preview measured |
| LMArena WebDev: React | 1701 | 1586 | Kimi K3.1 Pro |
| LMArena WebDev: HTML | 1706 | 1555 | Kimi K3.1 Pro |
| LMArena WebDev: from an image | Not measured | 1550 | Only Step 5 Preview measured |
| Neither model has a result on the other 29 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Kimi K3.1 Pro | Step 5 Preview | Leader |
|---|---|---|---|
| AA Intelligence Index | 46.0 | 28.5 | Kimi K3.1 Pro |
| Neither model has a result on the other 1 board here | |||
Agentic workLike-for-likePublic boards, shown as published, kept out of the index62
| Benchmark | Kimi K3.1 Pro | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench research | 77.9% | 72.8% | Kimi K3.1 Pro |
| LiveBench browser | 75.9% | 24.8% | Kimi K3.1 Pro |
| LiveBench long agentic | 39.1% | 19.4% | Kimi K3.1 Pro |
| 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) | 24.9% | 27.3% | Step 5 Preview |
| Legal Research Bench (Vals AI) | 37.5% | 40.4% | Step 5 Preview |
| Harvey's Legal Agent Benchmark (Vals AI) | 11.7% | Not measured | Only Kimi K3.1 Pro measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 57.1% | Only Step 5 Preview measured |
| BioMysteryBench (Vals AI) | 75.6% | 67.4% | Kimi K3.1 Pro |
| Terminal-Bench-Science (Vals AI) | 31.4% | 2.9% | Kimi K3.1 Pro |
| Vals Science Index | 44.4% | 29.6% | Kimi K3.1 Pro |
| Neither model has a result on the other 30 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Kimi K3.1 Pro | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench reasoning | 91.1% | 83.8% | Kimi K3.1 Pro |
| MysteryMechanism (Vals AI) | 26.1% | 18.5% | Kimi K3.1 Pro |
| Humanity's Last Exam (Artificial Analysis run) | 52.5% | 46.5% | Kimi K3.1 Pro |
| 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 | 1461 | 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 15 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Kimi K3.1 Pro | Step 5 Preview | Leader |
|---|---|---|---|
| ProofBench | 91.0% | 42.0% | Kimi K3.1 Pro |
| LMArena Text: math | Not measured | 1457 | Only Step 5 Preview measured |
| LMArena Text: mathematical work | Not measured | 1462 | Only Step 5 Preview measured |
| MathArena | 59.6% | Not measured | Only Kimi K3.1 Pro measured |
| Neither model has a result on the other 10 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index4 boards, none shared
| Benchmark | Kimi K3.1 Pro | Step 5 Preview | Leader |
|---|---|---|---|
| LMArena Text: science | Not measured | 1459 | 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 | 1441 | Only Step 5 Preview measured |
| LMArena Text: business and finance | Not measured | 1443 | Only Step 5 Preview measured |
| Neither model has a result on the other 16 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Kimi K3.1 Pro | Step 5 Preview | Leader |
|---|---|---|---|
| Design Arena: websites | 1325 | Not measured | Only Kimi K3.1 Pro measured |
| Design Arena: UI components | 1400 | Not measured | Only Kimi K3.1 Pro measured |
| Design Arena: game dev | 1410 | Not measured | Only Kimi K3.1 Pro measured |
| Design Arena: data viz | 1300 | Not measured | Only Kimi K3.1 Pro measured |
| Design Arena: 3D | 1451 | Not measured | Only Kimi K3.1 Pro measured |
| Design Arena: all code categories | 1354 | Not measured | Only Kimi K3.1 Pro measured |
| Design Arena: SVG | 1328 | Not measured | Only Kimi K3.1 Pro measured |
| LiveBench design | 77.8% | 76.9% | Kimi K3.1 Pro |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index11
| Benchmark | Kimi K3.1 Pro | Step 5 Preview | Leader |
|---|---|---|---|
| Vals Index | 62.5% | Not measured | Only Kimi K3.1 Pro measured |
| LiveBench data analysis | 79.1% | 63.5% | Kimi K3.1 Pro |
| Public Benefits Bench (Vals AI) | Not measured | 58.1% | Only Step 5 Preview measured |
| Long context reasoning (AA-LCR) | 86.3% | 88.3% | Step 5 Preview |
| LMArena Text | Not measured | 1443 | Only Step 5 Preview measured |
| LMArena Text: instruction following | Not measured | 1441 | Only Step 5 Preview measured |
| LMArena Text: creative writing | Not measured | 1413 | Only Step 5 Preview measured |
| LMArena Vision | Not measured | 1265 | Only Step 5 Preview measured |
| LMArena Text: English | Not measured | 1454 | Only Step 5 Preview measured |
| LMArena Text: non-English | Not measured | 1429 | Only Step 5 Preview measured |
| LMArena Text: Chinese | Not measured | 1502 | Only Step 5 Preview measured |
| LMArena Text: German | Not measured | 1454 | Only Step 5 Preview measured |
| LMArena Text: Japanese | Not measured | 1398 | Only Step 5 Preview measured |
| LMArena Text: Korean | Not measured | 1415 | Only Step 5 Preview measured |
| LMArena Text: French | Not measured | 1440 | Only Step 5 Preview measured |
| LMArena Text: Spanish | Not measured | 1444 | Only Step 5 Preview measured |
| LMArena Text: Russian | Not measured | 1431 | Only Step 5 Preview measured |
| LMArena Text: Polish | Not measured | 1390 | Only Step 5 Preview measured |
| LMArena Text: multi-turn | Not measured | 1437 | Only Step 5 Preview measured |
| LMArena Text: longer queries | Not measured | 1452 | Only Step 5 Preview measured |
| LMArena Text: writing and language | Not measured | 1427 | 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 24 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Kimi K3.1 Pro | 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
Step 5 Preview costs less
Repository review
50K input + 3K output tokens
Step 5 Preview costs less
Agent loop
200K input + 10K output tokens
Step 5 Preview 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 | MoonshotAI Kimi K3.1 Pro | StepFun Step 5 Preview |
|---|---|---|
| Maker | Moonshot AI | StepFun |
| Weights | No public weights listed | Open weights |
| Released | October 23, 2026 | October 8, 2026 |
| Context window | 1.05M | 1.05M |
| Input $/Mtok | $2.00 | $1.00 |
| Output $/Mtok | $10.00 | $2.70 |
| Coding index | 82.2 | 61.2 |
| Independent measurements behind it | 4 | 4 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Kimi K3.1 Pro better than Step 5 Preview for coding?
Pick Kimi K3.1 Pro for coding: it scores 82.2 on the Vibe Coding Index against 61.2 for Step 5 Preview. Pick Step 5 Preview for output tokens 3.7x cheaper ($2.70 vs $10.00 per million) and work measured by LiveBench coding or Tax Agent Bench (Vals AI), where it leads.
Which is cheaper, Kimi K3.1 Pro or Step 5 Preview?
Kimi K3.1 Pro costs $2.00 per million input tokens and $10.00 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, Kimi K3.1 Pro or Step 5 Preview?
Neither: both take 1.05M tokens.
How many benchmarks is the Kimi K3.1 Pro vs Step 5 Preview comparison based on?
24 benchmarks have a result for both models as of October 29, 2026. Kimi K3.1 Pro's coding index rests on 4 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.