Model comparison
Claude Opus 4.1 vs Kimi K2 (Jul 2025)
Claude Opus 4.1 and Kimi K2 (Jul 2025) score almost the same on the Noometry Index (41.0 vs 41.2), so choose on price, context window or the category you care about most.
Last verified . 29 shared benchmarks.
Summary
- They share 29 benchmarks with published results for both. Claude Opus 4.1 scores higher in 8 categories and Kimi K2 (Jul 2025) in 1 category; 8 gaps are clear of the uncertainty.
- The widest gap is in math, where Kimi K2 (Jul 2025) leads 42.7 to 22.3.
- The biggest single-benchmark swing is SimpleBench: 60% for Claude Opus 4.1 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 $15 / $75 for Claude Opus 4.1.
- Kimi K2 (Jul 2025) accepts more context: 262K tokens versus 200K.
- Kimi K2 (Jul 2025) has downloadable open weights; the other is API-only.
Side by side
| Claude Opus 4.1 | Kimi K2 (Jul 2025) | |
|---|---|---|
| Provider | Anthropic | Moonshot AI |
| Noometry Index | 41.0 | 41.2 |
| Released | 2025-08-05 | 2025-07-12 |
| Weights | Proprietary | Open |
| Context window | 200K | 262K |
| Max output | 32K | 262K |
| Input $ / M tokens | $15 | $0.57 |
| Output $ / M tokens | $75 | $2.30 |
| Results tracked | 48 | 42 |
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Category by category
Coding Claude Opus 4.1 leads
Claude Opus 4.1: 44.4 (#73), Kimi K2 (Jul 2025): 42.4 (#102)
| Benchmark | Claude Opus 4.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| WeirdML | 45.9% | 42.8% |
| LMArena Coding | 1479 | 1399 |
| ALE-Bench | 674.77 | 597.5 |
| SWE-bench Verified | 73.3% | — |
| SWE-bench Verified (bash only) | — | 63.4% |
| Aider Polyglot | — | 59.1% |
| LMArena WebDev | 1390 | — |
| GSO | — | 4.9% |
| AlgoTune | 1.34 | — |
Agentic & Tool Use Claude Opus 4.1 leads
Claude Opus 4.1: 35.0 (#41), Kimi K2 (Jul 2025): 32.4 (#64)
| Benchmark | Claude Opus 4.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| Terminal-Bench | 38% | 35.7% |
| METR Time Horizons | 66.8% | 59.2% |
| Berkeley Function Calling Leaderboard | — | 59.1% |
| GDPval | 43.6% | — |
| Cybench | 42% | — |
| DeepResearch Bench | 48.3% | — |
| LMArena Search | 1148 | — |
Reasoning Claude Opus 4.1 leads
Claude Opus 4.1: 32.2 (#76), Kimi K2 (Jul 2025): 23.3 (#179)
| Benchmark | Claude Opus 4.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| SimpleBench | 60% | 26.3% |
| LMArena Hard Prompts | 1443 | 1384 |
| Epoch Capabilities Index | 144.12 | 146.01 |
| ForecastBench | 62 | 60.2 |
| Kagi LLM Benchmark | — | 64.4% |
| Chess Puzzles | 7% | — |
| EnigmaEval | 7.2% | — |
| EBR-Bench | 7.9% | — |
| Mystery Game Puzzles | 21% | — |
| DTBench | 80% | — |
| LMCA | 37.1% | — |
Math Kimi K2 (Jul 2025) leads
Claude Opus 4.1: 22.3 (#277), Kimi K2 (Jul 2025): 42.7 (#83)
| Benchmark | Claude Opus 4.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Math | 1431 | 1397 |
| FrontierMath (Feb 2025 set) | 7.2% | 21.4% |
| FrontierMath Tier 4 (v1) | 4.2% | 0% |
| FrontierMath (Tiers 1-3) | 12.6% | — |
| FrontierMath Tier 4 | 2.4% | — |
| OTIS Mock AIME 2024-2025 | 68.9% | — |
| Omni-MATH | — | 65.4% |
Knowledge Claude Opus 4.1 leads
Claude Opus 4.1: 42.0 (#101), Kimi K2 (Jul 2025): 37.3 (#157)
| Benchmark | Claude Opus 4.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| Confabulations | 17.1% | 20.4% |
| Vectara Hallucination Rate | 11.8% | 17.9% |
| LMArena Expert | 1439 | 1365 |
| GPQA Diamond | 77.3% | — |
| Humanity's Last Exam | 11.5% | — |
| MMLU-Pro | — | 81.9% |
| GPQA (HELM) | — | 65.3% |
Multimodal Not comparable
Claude Opus 4.1: 26.8 (#119), Kimi K2 (Jul 2025): —
| Benchmark | Claude Opus 4.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| VPCT | 35% | — |
Multilingual Claude Opus 4.1 leads
Claude Opus 4.1: 52.0 (#95), Kimi K2 (Jul 2025): 49.6 (#130)
| Benchmark | Claude Opus 4.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Non-English | 1405 | 1372 |
| LMArena Chinese | 1427 | 1415 |
| LMArena French | 1431 | 1379 |
| LMArena German | 1413 | 1387 |
| LMArena Japanese | 1378 | 1349 |
| LMArena Korean | 1380 | 1325 |
| LMArena Russian | 1422 | 1385 |
| LMArena Spanish | 1448 | 1386 |
Instruction Following Claude Opus 4.1 leads
Claude Opus 4.1: 75.6 (#58), Kimi K2 (Jul 2025): 71.1 (#156)
| Benchmark | Claude Opus 4.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Instruction Following | 1435 | 1348 |
| IFEval | — | 85% |
Long Context Claude Opus 4.1 leads
Claude Opus 4.1: 44.5 (#63), Kimi K2 (Jul 2025): 41.2 (#145)
| Benchmark | Claude Opus 4.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Longer Query | 1455 | 1353 |
| Fiction.LiveBench | — | 66.7% |
| CL-bench | — | 17.6% |
Writing & Preference Too close to call
Claude Opus 4.1: 62.4 (#74), Kimi K2 (Jul 2025): 62.3 (#78)
| Benchmark | Claude Opus 4.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Text | 1419 | 1380 |
| LMArena Creative Writing | 1412 | 1350 |
| Short-Story Creative Writing | 84.7% | 85.6% |
| LMArena Multi-Turn | 1444 | 1371 |
| EQ-Bench Creative Writing | — | 1666 |
| WildBench | — | 86.2% |
Frequently asked questions
Is Claude Opus 4.1 better than Kimi K2 (Jul 2025)?
Claude Opus 4.1 and Kimi K2 (Jul 2025) score almost the same on the Noometry Index (41.0 vs 41.2), so choose on price, context window or the category you care about most.
Which is cheaper, Claude Opus 4.1 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 4.1 lists at $15 and $75.
Is Claude Opus 4.1 or Kimi K2 (Jul 2025) better for coding?
Claude Opus 4.1 scores higher on coding benchmarks: 44.4 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 4.1 and Kimi K2 (Jul 2025) share?
29 benchmarks have published results for both models. Claude Opus 4.1 has 48 scored results on Noometry and Kimi K2 (Jul 2025) has 42.