# Claude Opus 4.5 vs Kimi K2 (Jul 2025)

> Claude Opus 4.5 is the stronger model overall, scoring 50.5 to 41.2 on the Noometry Index. Kimi K2 (Jul 2025) costs 10.0× less per token, which makes it the better buy when Claude Opus 4.5's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/claude-opus-4-5-vs-kimi-k2
- Last updated: 2026-10-10
- Shared benchmarks: 33

## Summary

- They share 33 benchmarks with published results for both. Claude Opus 4.5 scores higher in 8 categories and Kimi K2 (Jul 2025) in 1 category; 9 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Claude Opus 4.5 leads 42.6 to 23.3.
- The biggest single-benchmark swing is SimpleBench: 62% for Claude Opus 4.5 and 26.3% for Kimi K2 (Jul 2025).
- Kimi K2 (Jul 2025) is cheaper at $0.57 / $2.30 per million input/output tokens, against $5 / $25 for Claude Opus 4.5.
- Kimi K2 (Jul 2025) accepts more context: 262K tokens versus 200K.
- Kimi K2 (Jul 2025) has downloadable open weights; the other is API-only.

## Snapshot

| | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| Provider | Anthropic | Moonshot AI |
| Noometry Index | 50.5 | 41.2 |
| Rank | 47 | 140 |
| Context | 200K | 262K |
| Input $/M | $5 | $0.57 |
| Output $/M | $25 | $2.30 |
| Weights | Proprietary | Open |

## Coding

- Claude Opus 4.5: 54.8 (#27)
- Kimi K2 (Jul 2025): 42.4 (#102)

| Benchmark | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| SWE-bench Verified (bash only) | 76.8% | 63.4% |
| GSO | 26.5% | 4.9% |
| WeirdML | 63.7% | 42.8% |
| LMArena Coding | 1504 | 1399 |
| ALE-Bench | 1,025 | 597.5 |
| SWE-bench Verified | 76.7% | — |
| Aider Polyglot | — | 59.1% |
| LMArena WebDev | 1494 | — |
| SWE-bench Multilingual | 70.7% | — |
| AlgoTune | 1.77 | — |

## Agentic & Tool Use

- Claude Opus 4.5: 47.3 (#12)
- Kimi K2 (Jul 2025): 32.4 (#64)

| Benchmark | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| Terminal-Bench | 63.1% | 35.7% |
| Berkeley Function Calling Leaderboard | 77.5% | 59.1% |
| METR Time Horizons | 75% | 59.2% |
| GDPval | 45.5% | — |
| Remote Labor Index | 3.8% | — |
| τ²-bench Airline | 84% | — |
| τ²-bench Banking | 24.7% | — |
| τ²-bench Retail | 79.6% | — |
| τ²-bench Telecom | 92.3% | — |
| Cybench | 82% | — |
| DeepResearch Bench | 54.8% | — |
| OSWorld | 66.3% | — |
| BALROG | 43.5% | — |
| LMArena Search | 1180 | — |
| Vending-Bench 2 | 4,967 | — |

## Reasoning

- Claude Opus 4.5: 42.6 (#51)
- Kimi K2 (Jul 2025): 23.3 (#179)

| Benchmark | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| SimpleBench | 62% | 26.3% |
| Kagi LLM Benchmark | 80.2% | 64.4% |
| LMArena Hard Prompts | 1476 | 1384 |
| Epoch Capabilities Index | 150.09 | 146.01 |
| ForecastBench | 60.7 | 60.2 |
| ARC-AGI-2 | 37.6% | — |
| NYT Connections (extended) | 52.5% | — |
| ARC-AGI-1 | 80% | — |
| Chess Puzzles | 12% | — |
| EnigmaEval | 11.9% | — |
| EBR-Bench | 14.3% | — |
| Mystery Game Puzzles | 22% | — |
| DTBench | 89.9% | — |
| LMCA | 44.5% | — |

## Math

- Claude Opus 4.5: 38.6 (#132)
- Kimi K2 (Jul 2025): 42.7 (#83)

| Benchmark | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Math | 1463 | 1397 |
| FrontierMath (Feb 2025 set) | 20.7% | 21.4% |
| FrontierMath Tier 4 (v1) | 4.2% | 0% |
| FrontierMath (Tiers 1-3) | 34.4% | — |
| FrontierMath Tier 4 | 4.9% | — |
| OTIS Mock AIME 2024-2025 | 86.1% | — |
| ProofBench | 36% | — |
| Omni-MATH | — | 65.4% |

## Knowledge

- Claude Opus 4.5: 56.5 (#44)
- Kimi K2 (Jul 2025): 37.3 (#157)

| Benchmark | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| Vectara Hallucination Rate | 10.9% | 17.9% |
| LMArena Expert | 1487 | 1365 |
| GPQA Diamond | 86% | — |
| Humanity's Last Exam | 25.2% | — |
| SimpleQA Verified | 45.7% | — |
| MMLU-Pro | — | 81.9% |
| Confabulations | — | 20.4% |
| GPQA (HELM) | — | 65.3% |

## Multimodal

- Claude Opus 4.5: 31.4 (#107)
- Kimi K2 (Jul 2025): —

| Benchmark | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| GeoBench | 75% | — |
| VPCT | 40% | — |
| Furniture Assembly | 28.3% | — |
| LMArena Document | 1462 | — |

## Multilingual

- Claude Opus 4.5: 54.3 (#47)
- Kimi K2 (Jul 2025): 49.6 (#130)

| Benchmark | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Non-English | 1438 | 1372 |
| LMArena Chinese | 1470 | 1415 |
| LMArena French | 1471 | 1379 |
| LMArena German | 1449 | 1387 |
| LMArena Japanese | 1416 | 1349 |
| LMArena Korean | 1424 | 1325 |
| LMArena Russian | 1447 | 1385 |
| LMArena Spanish | 1458 | 1386 |

## Instruction Following

- Claude Opus 4.5: 77.5 (#19)
- Kimi K2 (Jul 2025): 71.1 (#156)

| Benchmark | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Instruction Following | 1478 | 1348 |
| IFEval | — | 85% |

## Long Context

- Claude Opus 4.5: 46.5 (#22)
- Kimi K2 (Jul 2025): 41.2 (#145)

| Benchmark | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| CL-bench | 21.1% | 17.6% |
| LMArena Longer Query | 1480 | 1353 |
| Fiction.LiveBench | — | 66.7% |

## Writing & Preference

- Claude Opus 4.5: 68.1 (#28)
- Kimi K2 (Jul 2025): 62.3 (#78)

| Benchmark | Claude Opus 4.5 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Text | 1451 | 1380 |
| LMArena Creative Writing | 1445 | 1350 |
| EQ-Bench Creative Writing | 1687 | 1666 |
| LMArena Multi-Turn | 1466 | 1371 |
| Short-Story Creative Writing | — | 85.6% |
| WildBench | — | 86.2% |

## FAQ

### Is Claude Opus 4.5 better than Kimi K2 (Jul 2025)?

Claude Opus 4.5 is the stronger model overall, scoring 50.5 to 41.2 on the Noometry Index. Kimi K2 (Jul 2025) costs 10.0× less per token, which makes it the better buy when Claude Opus 4.5's lead doesn't matter for your workload.

### Which is cheaper, Claude Opus 4.5 or Kimi K2 (Jul 2025)?

Kimi K2 (Jul 2025) is cheaper. It lists at $0.57 per million input tokens and $2.30 per million output tokens; Claude Opus 4.5 lists at $5 and $25.

### Is Claude Opus 4.5 or Kimi K2 (Jul 2025) better for coding?

Claude Opus 4.5 scores higher on coding benchmarks: 54.8 versus 42.4 in the Noometry coding category.

### Which has the bigger context window?

Kimi K2 (Jul 2025) does, with 262K tokens against 200K.

### How many benchmarks do Claude Opus 4.5 and Kimi K2 (Jul 2025) share?

33 benchmarks have published results for both models. Claude Opus 4.5 has 69 scored results on Noometry and Kimi K2 (Jul 2025) has 42.