Claude Opus 5.5 vs Kimi K3.1 Pro
Claude Opus 5.5 leads Kimi K3.1 Pro on coding, 88.9 to 82.2 on the Vibe Coding Index, and Kimi K3.1 Pro costs 2.0x less per output token ($10.00 vs $20.00 per million). Updated October 29, 2026; 35 benchmarks have a result for both.
vs boards won of 35 shared
Claude Opus 5.5 or Kimi K3.1 Pro: which to pick
Pick Claude Opus 5.5 for coding: it scores 88.9 on the Vibe Coding Index against 82.2 for Kimi K3.1 Pro.
Pick Kimi K3.1 Pro for output tokens 2.0x cheaper ($10.00 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).
Model AClaude Opus 5.5Anthropic88.9/1005 independent benchmarksNo cost per solved taskModel BKimi K3.1 ProMoonshot AI82.2/1004 independent benchmarksNo cost per solved task
- Shared results
- 35
- Claude Opus 5.5 only
- 80
- Kimi K3.1 Pro only
- 0
- 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
Claude Opus 5.5
Claude Opus 5.5 scores 88.9 against 82.2.
5 and 4 benchmarks behind the scores
Intelligence
AA Intelligence Index
Claude Opus 5.5
Claude Opus 5.5 leads, 58.4 against 46.0.
Same board, both measured
Web design
Design Arena: websites
Claude Opus 5.5
Claude Opus 5.5 leads, 1326 against 1325.
Same board, both measured
General
Vals Index
Claude Opus 5.5
Claude Opus 5.5 leads, 70.2% against 62.5%.
Same board, both measured
Long documents
Listed context window
Kimi K3.1 Pro
Kimi K3.1 Pro takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Kimi K3.1 Pro
Claude Opus 5.5 $0.014, Kimi K3.1 Pro $0.0070 per turn.
List prices
At a glance
- Coding index
- Claude Opus 5.5 88.9 from 5 benchmarks, Kimi K3.1 Pro 82.2 from 4 benchmarks.
- Widest category
- Math, 14.2 points apart on average over 2 shared benchmarks.
- Widest single gap
- LiveBench long agentic: Claude Opus 5.5 72.8% against Kimi K3.1 Pro 39.1%, 33.7 points apart on a 0 to 100 scale.
- Output price
- Claude Opus 5.5 $20.00 against Kimi K3.1 Pro $10.00 per million output tokens, 2.0x apart.
- Context window
- Claude Opus 5.5 takes 1M tokens, Kimi K3.1 Pro 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 | Claude Opus 5.5 | Bars | Kimi K3.1 Pro | Ties |
|---|---|---|---|---|
| Coding | 9 | 0 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 8 | 1 | ||
| Reasoning | 3 | 0 | ||
| Math | 2 | 0 | ||
| Web design | 6 | 2 | ||
| General | 2 | 1 | ||
| All shared boards | 31 | 4 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index90
| Benchmark | Claude Opus 5.5 | Kimi K3.1 Pro | Leader |
|---|---|---|---|
| LiveBench coding | 96.3% | 81.8% | Claude Opus 5.5 |
| LMArena WebDev | 1810 | 1695 | Claude Opus 5.5 |
| Terminal-Bench 4 (Vals AI) | 65.2% | 63.6% | Claude Opus 5.5 |
| Vibe Code Bench (Vals AI) | 90.3% | 84.9% | Claude Opus 5.5 |
| Code migration (Vals AI) | 66.7% | Not measured | Only Claude Opus 5.5 measured |
| ProgramBench (Vals AI) | 18.5% | Not measured | Only Claude Opus 5.5 measured |
| IOI (Vals AI) | 95.1% | 81.9% | Claude Opus 5.5 |
| Terminal-Bench 2.1 (Vals AI) | 87.6% | Not measured | Only Claude Opus 5.5 measured |
| SWE-bench Multimodal (Vals AI) | 70.2% | Not measured | Only Claude Opus 5.5 measured |
| Vibe Code Bench 1-100 (Vals AI) | 30.4% | Not measured | Only Claude Opus 5.5 measured |
| CyberBench (Vals AI) | 74.6% | Not measured | Only Claude Opus 5.5 measured |
| SciCode | 66.9% | 60.8% | Claude Opus 5.5 |
| FrontierCode | 54.6% | Not measured | Only Claude Opus 5.5 measured |
| FrontierSWE | 62.3% | Not measured | Only Claude Opus 5.5 measured |
| MirrorCode | 77.4% | Not measured | Only Claude Opus 5.5 measured |
| ALE-Bench | 2147.4 | 1932.8 | Claude Opus 5.5 |
| LMArena Text: coding | 1547 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: software and IT | 1538 | Not measured | Only Claude Opus 5.5 measured |
| LMArena WebDev: React | 1860 | 1701 | Claude Opus 5.5 |
| LMArena WebDev: HTML | 1753 | 1706 | Claude Opus 5.5 |
| LMArena WebDev: from an image | 1753 | Not measured | Only Claude Opus 5.5 measured |
| SciCode | 18.5% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 21 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Opus 5.5 | Kimi K3.1 Pro | Leader |
|---|---|---|---|
| AA Intelligence Index | 58.4 | 46.0 | Claude Opus 5.5 |
| Epoch Capabilities Index | 168.8 | Not measured | Only Claude Opus 5.5 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index81
| Benchmark | Claude Opus 5.5 | Kimi K3.1 Pro | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | 1320 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: agents building mobile apps | 1307 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: spreadsheets | 1395 | Not measured | Only Claude Opus 5.5 measured |
| LiveBench research | 85.0% | 77.9% | Claude Opus 5.5 |
| LiveBench browser | 88.4% | 75.9% | Claude Opus 5.5 |
| LiveBench long agentic | 72.8% | 39.1% | Claude Opus 5.5 |
| SREBench (Vals AI) | 33.6% | Not measured | Only Claude Opus 5.5 measured |
| Finance Agent (Vals AI) | 58.6% | Not measured | Only Claude Opus 5.5 measured |
| Tax Agent Bench (Vals AI) | 45.6% | 24.9% | Claude Opus 5.5 |
| Legal Research Bench (Vals AI) | 50.5% | 37.5% | Claude Opus 5.5 |
| Harvey's Legal Agent Benchmark (Vals AI) | 9.2% | 11.7% | Kimi K3.1 Pro |
| Excel Modeling Benchmark (Vals AI) | 75.9% | Not measured | Only Claude Opus 5.5 measured |
| BioMysteryBench (Vals AI) | 79.3% | 75.6% | Claude Opus 5.5 |
| Terminal-Bench-Science (Vals AI) | 47.1% | 31.4% | Claude Opus 5.5 |
| Vals Science Index | 58.7% | 44.4% | Claude Opus 5.5 |
| Time Horizon Index (Vals AI) | 91.3% | Not measured | Only Claude Opus 5.5 measured |
| CUA-bench (Vals AI) | 14.0% | Not measured | Only Claude Opus 5.5 measured |
| Robo-bench (Vals AI) | 14.6% | Not measured | Only Claude Opus 5.5 measured |
| APEX-Agents | 73.5% | Not measured | Only Claude Opus 5.5 measured |
| Remote Labor Index | 21.3% | Not measured | Only Claude Opus 5.5 measured |
| SpireClimb | 3.3% | Not measured | Only Claude Opus 5.5 measured |
| Vending-Bench 2 | $9,235 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Search | 1213 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 19 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Claude Opus 5.5 | Kimi K3.1 Pro | Leader |
|---|---|---|---|
| LiveBench reasoning | 92.2% | 91.1% | Claude Opus 5.5 |
| MysteryMechanism (Vals AI) | 49.5% | 26.1% | Claude Opus 5.5 |
| Humanity's Last Exam (Artificial Analysis run) | 61.4% | 52.5% | Claude Opus 5.5 |
| GPQA Diamond (Epoch AI run) | 90.6% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI | 98.5% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI-2 | 93.3% | Not measured | Only Claude Opus 5.5 measured |
| Chess puzzles | 67.0% | Not measured | Only Claude Opus 5.5 measured |
| Mystery game puzzles | 71.0% | Not measured | Only Claude Opus 5.5 measured |
| EBR-bench | 71.4% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: hard prompts | 1536 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: expert | 1548 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: hard prompts in English | 1539 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision: diagrams | 1345 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision: homework | 1362 | Not measured | Only Claude Opus 5.5 measured |
| Humanity's Last Exam (Scale run) | 55.0% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 8 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Opus 5.5 | Kimi K3.1 Pro | Leader |
|---|---|---|---|
| OTIS Mock AIME | 100.0% | Not measured | Only Claude Opus 5.5 measured |
| FrontierMath, tiers 1 to 3 | 91.2% | Not measured | Only Claude Opus 5.5 measured |
| FrontierMath, tier 4 | 95.0% | Not measured | Only Claude Opus 5.5 measured |
| ProofBench | 100.0% | 91.0% | Claude Opus 5.5 |
| LMArena Text: math | 1517 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: mathematical work | 1526 | Not measured | Only Claude Opus 5.5 measured |
| MathArena | 79.0% | 59.6% | Claude Opus 5.5 |
| Neither model has a result on the other 7 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | Claude Opus 5.5 | Kimi K3.1 Pro | Leader |
|---|---|---|---|
| MedCode (Vals AI) | 49.8% | Not measured | Only Claude Opus 5.5 measured |
| SimpleQA Verified | 72.2% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: science | 1520 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: medicine and healthcare | 1510 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: legal and government | 1512 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: business and finance | 1497 | Not measured | Only Claude Opus 5.5 measured |
| FACTS Benchmark Suite | 64.0% | Not measured | Only Claude Opus 5.5 measured |
| PRBench Legal | 47.6% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 12 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index62
| Benchmark | Claude Opus 5.5 | Kimi K3.1 Pro | Leader |
|---|---|---|---|
| Design Arena: websites | 1326 | 1325 | Claude Opus 5.5 |
| Design Arena: UI components | 1378 | 1400 | Kimi K3.1 Pro |
| Design Arena: game dev | 1436 | 1410 | Claude Opus 5.5 |
| Design Arena: data viz | 1394 | 1300 | Claude Opus 5.5 |
| Design Arena: 3D | 1466 | 1451 | Claude Opus 5.5 |
| Design Arena: all code categories | 1385 | 1354 | Claude Opus 5.5 |
| Design Arena: SVG | 1323 | 1328 | Kimi K3.1 Pro |
| Design Arena: ASCII art | 1351 | Not measured | Only Claude Opus 5.5 measured |
| LiveBench design | 86.9% | 77.8% | Claude Opus 5.5 |
GeneralLike-for-likePublic boards, shown as published, kept out of the index21
| Benchmark | Claude Opus 5.5 | Kimi K3.1 Pro | Leader |
|---|---|---|---|
| Vals Index | 70.2% | 62.5% | Claude Opus 5.5 |
| LiveBench data analysis | 80.3% | 79.1% | Claude Opus 5.5 |
| Public Benefits Bench (Vals AI) | 70.6% | Not measured | Only Claude Opus 5.5 measured |
| SAGE (Vals AI) | 91.3% | Not measured | Only Claude Opus 5.5 measured |
| MedScribe (Vals AI) | 91.4% | Not measured | Only Claude Opus 5.5 measured |
| Long context reasoning (AA-LCR) | 84.7% | 86.3% | Kimi K3.1 Pro |
| DTBench | 98.9% | Not measured | Only Claude Opus 5.5 measured |
| LMCA | 68.2% | Not measured | Only Claude Opus 5.5 measured |
| Furniture assembly | 83.3% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text | 1516 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: instruction following | 1539 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: creative writing | 1534 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision | 1321 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: English | 1521 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: non-English | 1506 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: Chinese | 1583 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: German | 1496 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: Japanese | 1538 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: French | 1496 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: Spanish | 1504 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: Russian | 1515 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: multi-turn | 1500 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: longer queries | 1533 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: writing and language | 1531 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: entertainment and media | 1514 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision: English | 1317 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision: reading text | 1326 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision: creative writing | 1320 | Not measured | Only Claude Opus 5.5 measured |
| EQ-Bench 4 | 1340 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 19 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Opus 5.5 | Kimi K3.1 Pro | 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
Claude Opus 5.5$0.014Fits in one request
Kimi K3.1 Pro$0.0070Fits in one request
Kimi K3.1 Pro costs less
Repository review
50K input + 3K output tokens
Claude Opus 5.5$0.260Fits in one request
Kimi K3.1 Pro$0.130Fits in one request
Kimi K3.1 Pro costs less
Agent loop
200K input + 10K output tokens
Claude Opus 5.5$1.00Fits in one request
Kimi K3.1 Pro$0.500Fits in one request
Kimi K3.1 Pro 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 | Anthropic Claude Opus 5.5 | MoonshotAI Kimi K3.1 Pro |
|---|---|---|
| Maker | Anthropic | Moonshot AI |
| Weights | No public weights listed | No public weights listed |
| Released | September 22, 2026 | October 23, 2026 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $4.00 | $2.00 |
| Output $/Mtok | $20.00 | $10.00 |
| Coding index | 88.9 | 82.2 |
| Independent measurements behind it | 5 | 4 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Opus 5.5 better than Kimi K3.1 Pro for coding?
Pick Claude Opus 5.5 for coding: it scores 88.9 on the Vibe Coding Index against 82.2 for Kimi K3.1 Pro. Pick Kimi K3.1 Pro for output tokens 2.0x cheaper ($10.00 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).
Which is cheaper, Claude Opus 5.5 or Kimi K3.1 Pro?
Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; Kimi K3.1 Pro costs $2.00 and $10.00. Cost per solved task is known for neither of them.
Which has the bigger context window, Claude Opus 5.5 or Kimi K3.1 Pro?
Kimi K3.1 Pro, with 1.05M tokens against 1M.
How many benchmarks is the Claude Opus 5.5 vs Kimi K3.1 Pro comparison based on?
35 benchmarks have a result for both models as of October 29, 2026. Claude Opus 5.5's coding index rests on 5 independent benchmarks and Kimi K3.1 Pro's on 4. Where only one model has a result, the page says so instead of naming a winner.