Claude Sonnet 4.5 vs Kimi K2.6
Anthropic Claude Sonnet 4.5 | Moonshot AI Kimi K2.6 | |
|---|---|---|
| Overview | ||
| Company | Anthropic | Moonshot AI |
| Release date | Sep 29 2025 | Apr 21 2026 |
| Access | Proprietary | Open Weight |
| Specifications | ||
Parameters | — | 1T |
Context window | — | 256k |
| Benchmarks | ||
Nonsense detection BullshitBench v2Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | 79%Best | 65% |
Coding SWE-Bench VerifiedReal coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | 77.2% | 80.2%Best |
Agentic coding CursorBench v3.1Cursor's own test of harder, real-world coding tasks inside a code editor. Higher is better. | — | 47.6% |
Next.js coding Next.js EvalsVercel's open eval of how well AI coding agents build and migrate real Next.js apps — measured as the share of tasks the agent completes successfully. Higher is better. | 50% | 67%Best |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 83.4% | 90.5%Best |
Multimodal MMMUTests the AI on understanding images and text together across many college subjects. Higher is better. | 68% | — |
| Timeline | ||
| Release gap | Claude Sonnet 4.5 shipped 204 days before Kimi K2.6 | |
Which is better: Claude Sonnet 4.5 or Kimi K2.6?
Kimi K2.6 leads Claude Sonnet 4.5 on 3 of the 4 benchmarks they both report (BullshitBench v2, SWE-Bench Verified, Next.js Evals, GPQA Diamond). Claude Sonnet 4.5 shipped 204 days before Kimi K2.6, so benchmark comparisons should account for the intervening progress.
Claude Sonnet 4.5 is proprietary, while Kimi K2.6 is open weight.
On BullshitBench v2, Claude Sonnet 4.5 leads at 79% vs Kimi K2.6 at 65%. On SWE-Bench Verified, Kimi K2.6 leads at 80.2% vs Claude Sonnet 4.5 at 77.2%. On Next.js Evals, Kimi K2.6 leads at 67% vs Claude Sonnet 4.5 at 50%. On GPQA Diamond, Kimi K2.6 leads at 90.5% vs Claude Sonnet 4.5 at 83.4%.
Frequently asked questions
Claude Sonnet 4.5 was released by Anthropic on Sep 29 2025.
Kimi K2.6 was released by Moonshot AI on Apr 21 2026.
Kimi K2.6 leads on SWE-Bench Verified — Claude Sonnet 4.5 77.2% vs Kimi K2.6 80.2%.
Kimi K2.6 leads on GPQA Diamond — Claude Sonnet 4.5 83.4% vs Kimi K2.6 90.5%.
Claude Sonnet 4.5 is a proprietary model released by Anthropic. Kimi K2.6 is an open weight model released by Moonshot AI.