Kimi K2.5 vs Step 5 Preview
Updated October 21, 2026. 42 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
Decision reading
Pick Step 5 Preview for coding: it scores 71.4 on the Vibe Coding Index against 58.5 for Kimi K2.5.
Pick Kimi K2.5 when output tokens cost 1.1x less, or when what matters is LMArena Text: hard prompts in English or LMArena Vision: homework, where it leads.
- Shared results
- 42
- Kimi K2.5 only
- 56
- Step 5 Preview only
- 19
- Like-for-like categories
- 7 of 9
Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.
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, four public coding benchmarks
Step 5 Preview
Step 5 Preview scores 71.4 against 58.5.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
Step 5 Preview
Step 5 Preview leads, 43.7 against 23.5.
Same board, both measured
Reasoning
GPQA Diamond
No call
Only Kimi K2.5 has a GPQA Diamond result, 84.1%.
Directional only
Math
AIME
No call
Only Kimi K2.5 has a AIME result, 95.6%.
Directional only
Knowledge
MMLU Pro
No call
Only Kimi K2.5 has a MMLU Pro result, 85.9%.
Directional only
Web design
Design Arena: websites
No call
Only Kimi K2.5 has a Design Arena: websites result, 1249.
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
Kimi K2.5
Kimi K2.5 $0.0018, Step 5 Preview $0.0024 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Kimi K2.5 has the number, $0.24.
Directional only
At a glance
- Coding index
- Kimi K2.5 58.5 from 2 benchmarks, Step 5 Preview 71.4 from 2 benchmarks.
- Widest category
- Agentic work, 22.7 points apart on average over 3 shared benchmarks.
- Widest single gap
- Vibe Code Bench (Vals AI): Kimi K2.5 17.5% against Step 5 Preview 70.4%, 52.9 points apart on a 0 to 100 scale.
- Output price
- Kimi K2.5 $2.50 against Step 5 Preview $2.70 per million output tokens, 1.1x apart.
- Context window
- Kimi K2.5 takes 262K tokens, Step 5 Preview 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 | Kimi K2.5 | Bars | Step 5 Preview | Ties |
|---|---|---|---|---|
| Coding | 0 | 8 | ||
| Intelligence | 0 | 1 | ||
| Agentic work | 0 | 3 | ||
| Reasoning | 2 | 4 | ||
| Math | 2 | 0 | ||
| Knowledge | 3 | 1 | ||
| General | 12 | 6 | ||
| All shared boards | 19 | 23 |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index08
| Benchmark | Kimi K2.5 | Step 5 Preview | Leader |
|---|---|---|---|
| SWE-bench Verified | 70.8% | Not measured | Only Kimi K2.5 measured |
| SWE-bench Multilingual | 67.3% | Not measured | Only Kimi K2.5 measured |
| LiveBench coding | Not measured | 85.6% | Only Step 5 Preview measured |
| LMArena WebDev | 1437 | 1567 | Step 5 Preview |
| AA Coding Index | 46.8 | Not measured | Only Kimi K2.5 measured |
| LiveCodeBench (Vals AI) | 83.9% | Not measured | Only Kimi K2.5 measured |
| SWE-bench Verified (Vals AI) | 70.0% | Not measured | Only Kimi K2.5 measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 31.8% | Only Step 5 Preview measured |
| Vibe Code Bench (Vals AI) | 17.5% | 70.4% | Step 5 Preview |
| Code migration (Vals AI) | 7.0% | 39.0% | Step 5 Preview |
| IOI (Vals AI) | Not measured | 38.1% | Only Step 5 Preview measured |
| Terminal-Bench 2.1 (Vals AI) | 42.0% | Not measured | Only Kimi K2.5 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 Hard (Artificial Analysis run) | 34.8% | Not measured | Only Kimi K2.5 measured |
| Terminal-Bench | 43.2% | Not measured | Only Kimi K2.5 measured |
| WeirdML | 45.6% | Not measured | Only Kimi K2.5 measured |
| ALE-Bench | 821.6 | Not measured | Only Kimi K2.5 measured |
| LMArena Text: coding | 1483 | 1485 | Step 5 Preview |
| LMArena Text: software and IT | 1471 | 1473 | Step 5 Preview |
| LMArena WebDev: React | 1429 | 1583 | Step 5 Preview |
| LMArena WebDev: HTML | 1426 | 1556 | Step 5 Preview |
| LMArena WebDev: from an image | 1439 | 1550 | Step 5 Preview |
| Neither model has a result on the other 15 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Kimi K2.5 | Step 5 Preview | Leader |
|---|---|---|---|
| AA Intelligence Index | 23.5 | 43.7 | Step 5 Preview |
| Epoch Capabilities Index | 148.1 | Not measured | Only Kimi K2.5 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index03
| Benchmark | Kimi K2.5 | Step 5 Preview | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | 1136 | Not measured | Only Kimi K2.5 measured |
| Design Arena: agents building full-stack apps | 1114 | Not measured | Only Kimi K2.5 measured |
| Design Arena: agents building mobile apps | 1147 | Not measured | Only Kimi K2.5 measured |
| Design Arena: agents building Android apps | 1124 | Not measured | Only Kimi K2.5 measured |
| Design Arena: agents building Godot games | 1219 | Not measured | Only Kimi K2.5 measured |
| 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) | 35.8% | 50.7% | Step 5 Preview |
| Tax Agent Bench (Vals AI) | Not measured | 27.3% | Only Step 5 Preview measured |
| Legal Research Bench (Vals AI) | 15.9% | 40.4% | Step 5 Preview |
| Excel Modeling Benchmark (Vals AI) | 28.5% | 57.1% | Step 5 Preview |
| 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 |
| τ²-Bench Telecom | 95.9% | Not measured | Only Kimi K2.5 measured |
| OSWorld | 63.3% | Not measured | Only Kimi K2.5 measured |
| Vending-Bench 2 | $1,198 | Not measured | Only Kimi K2.5 measured |
| Neither model has a result on the other 20 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index24
| Benchmark | Kimi K2.5 | Step 5 Preview | Leader |
|---|---|---|---|
| GPQA Diamond | 84.1% | Not measured | Only Kimi K2.5 measured |
| LiveBench reasoning | Not measured | 83.8% | Only Step 5 Preview measured |
| MysteryMechanism (Vals AI) | Not measured | 18.5% | Only Step 5 Preview measured |
| MMMU Pro (Vals AI) | 84.3% | Not measured | Only Kimi K2.5 measured |
| GPQA Diamond (Artificial Analysis run) | 87.9% | Not measured | Only Kimi K2.5 measured |
| Humanity's Last Exam (Artificial Analysis run) | 30.7% | 46.5% | Step 5 Preview |
| ARC-AGI | 65.3% | Not measured | Only Kimi K2.5 measured |
| ARC-AGI-2 | 11.8% | Not measured | Only Kimi K2.5 measured |
| SimpleBench | 46.8% | Not measured | Only Kimi K2.5 measured |
| LMArena Text: hard prompts | 1453 | 1461 | Step 5 Preview |
| LMArena Text: expert | 1466 | 1485 | Step 5 Preview |
| LMArena Text: hard prompts in English | 1460 | 1454 | Kimi K2.5 |
| LMArena Vision: diagrams | 1282 | 1308 | Step 5 Preview |
| LMArena Vision: homework | 1297 | 1265 | Kimi K2.5 |
| Neither model has a result on the other 7 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Kimi K2.5 | Step 5 Preview | Leader |
|---|---|---|---|
| AIME | 95.6% | Not measured | Only Kimi K2.5 measured |
| ProofBench | Not measured | 42.0% | Only Step 5 Preview measured |
| LMArena Text: math | 1470 | 1458 | Kimi K2.5 |
| LMArena Text: mathematical work | 1473 | 1460 | Kimi K2.5 |
| Neither model has a result on the other 9 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index31
| Benchmark | Kimi K2.5 | Step 5 Preview | Leader |
|---|---|---|---|
| MMLU Pro | 85.9% | Not measured | Only Kimi K2.5 measured |
| CaseLaw (Vals AI) | 58.7% | Not measured | Only Kimi K2.5 measured |
| CorpFin (Vals AI) | 68.3% | Not measured | Only Kimi K2.5 measured |
| TaxEval (Vals AI) | 74.2% | Not measured | Only Kimi K2.5 measured |
| MortgageTax (Vals AI) | 66.5% | Not measured | Only Kimi K2.5 measured |
| MedQA (Vals AI) | 94.4% | Not measured | Only Kimi K2.5 measured |
| MedCode (Vals AI) | 39.3% | Not measured | Only Kimi K2.5 measured |
| SimpleQA Verified | 34.3% | Not measured | Only Kimi K2.5 measured |
| LMArena Text: science | 1459 | 1454 | Kimi K2.5 |
| LMArena Text: medicine and healthcare | 1448 | 1439 | Kimi K2.5 |
| LMArena Text: legal and government | 1441 | 1437 | Kimi K2.5 |
| LMArena Text: business and finance | 1427 | 1435 | Step 5 Preview |
| Neither model has a result on the other 5 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index9 boards, none shared
| Benchmark | Kimi K2.5 | Step 5 Preview | Leader |
|---|---|---|---|
| Design Arena: websites | 1249 | Not measured | Only Kimi K2.5 measured |
| Design Arena: UI components | 1236 | Not measured | Only Kimi K2.5 measured |
| Design Arena: game dev | 1207 | Not measured | Only Kimi K2.5 measured |
| Design Arena: data viz | 1219 | Not measured | Only Kimi K2.5 measured |
| Design Arena: 3D | 1205 | Not measured | Only Kimi K2.5 measured |
| Design Arena: all code categories | 1236 | Not measured | Only Kimi K2.5 measured |
| Design Arena: SVG | 1149 | Not measured | Only Kimi K2.5 measured |
| Design Arena: ASCII art | 1165 | Not measured | Only Kimi K2.5 measured |
| LiveBench design | Not measured | 76.9% | Only Step 5 Preview measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index126
| Benchmark | Kimi K2.5 | 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 |
| SAGE (Vals AI) | 49.9% | Not measured | Only Kimi K2.5 measured |
| MedScribe (Vals AI) | 76.4% | Not measured | Only Kimi K2.5 measured |
| IFBench | 70.2% | Not measured | Only Kimi K2.5 measured |
| Long context reasoning (AA-LCR) | 78.0% | 88.3% | Step 5 Preview |
| Fiction.LiveBench | 86.1% | Not measured | Only Kimi K2.5 measured |
| CL-bench | 19.3% | Not measured | Only Kimi K2.5 measured |
| CL-bench Life | 13.2% | Not measured | Only Kimi K2.5 measured |
| LMArena Text | 1445 | 1440 | Kimi K2.5 |
| LMArena Text: instruction following | 1431 | 1438 | Step 5 Preview |
| LMArena Text: creative writing | 1422 | 1409 | Kimi K2.5 |
| LMArena Vision | 1269 | 1265 | Kimi K2.5 |
| LMArena Text: English | 1453 | 1447 | Kimi K2.5 |
| LMArena Text: non-English | 1433 | 1428 | Kimi K2.5 |
| LMArena Text: Chinese | 1494 | 1500 | Step 5 Preview |
| LMArena Text: German | 1441 | Not measured | Only Kimi K2.5 measured |
| LMArena Text: Japanese | 1423 | 1383 | Kimi K2.5 |
| LMArena Text: Korean | 1412 | Not measured | Only Kimi K2.5 measured |
| LMArena Text: French | 1454 | 1438 | Kimi K2.5 |
| LMArena Text: Spanish | 1450 | 1441 | Kimi K2.5 |
| LMArena Text: Russian | 1435 | 1433 | Kimi K2.5 |
| LMArena Text: Polish | 1445 | Not measured | Only Kimi K2.5 measured |
| LMArena Text: multi-turn | 1444 | 1437 | Kimi K2.5 |
| LMArena Text: longer queries | 1445 | 1449 | Step 5 Preview |
| LMArena Text: writing and language | 1425 | 1425 | Kimi K2.5 |
| LMArena Text: entertainment and media | 1417 | 1412 | Kimi K2.5 |
| LMArena Vision: English | 1274 | 1290 | Step 5 Preview |
| LMArena Vision: Chinese | 1328 | Not measured | Only Kimi K2.5 measured |
| LMArena Vision: reading text | 1276 | 1282 | Step 5 Preview |
| LMArena Vision: humor | 1284 | Not measured | Only Kimi K2.5 measured |
| LMArena Vision: captioning | 1257 | Not measured | Only Kimi K2.5 measured |
| LMArena Vision: recognizing things | 1285 | Not measured | Only Kimi K2.5 measured |
| LMArena Vision: creative writing | 1269 | Not measured | Only Kimi K2.5 measured |
| Neither model has a result on the other 12 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Kimi K2.5 | 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
Kimi K2.5 costs less
Repository review
50K input + 3K output tokens
Kimi K2.5 costs less
Agent loop
200K input + 10K output tokens
Kimi K2.5 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 K2.5 | StepFun Step 5 Preview |
|---|---|---|
| Maker | Moonshot AI | StepFun |
| Weights | Open weights | Open weights |
| Released | January 27, 2026 | October 8, 2026 |
| Context window | 262K | 1.05M |
| Input $/Mtok | $0.50 | $1.00 |
| Output $/Mtok | $2.50 | $2.70 |
| Coding index | 58.5 | 71.4 |
| Independent measurements behind it | 2 | 2 |
| Cost per solved task | $0.24 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Kimi K2.5 better than Step 5 Preview for coding?
Pick Step 5 Preview for coding: it scores 71.4 on the Vibe Coding Index against 58.5 for Kimi K2.5. Pick Kimi K2.5 when output tokens cost 1.1x less, or when what matters is LMArena Text: hard prompts in English or LMArena Vision: homework, where it leads.
Which is cheaper, Kimi K2.5 or Step 5 Preview?
Kimi K2.5 costs $0.50 per million input tokens and $2.50 per million output tokens; Step 5 Preview costs $1.00 and $2.70. Cost per solved task is known for Kimi K2.5 only.
Which has the bigger context window, Kimi K2.5 or Step 5 Preview?
Step 5 Preview, with 1.05M tokens against 262K.
How many benchmarks is the Kimi K2.5 vs Step 5 Preview comparison based on?
42 benchmarks have a result for both models as of October 21, 2026. Kimi K2.5's coding index rests on 2 independent benchmarks and Step 5 Preview's on 2. Where only one model has a result, the page says so instead of naming a winner.