Claude Sonnet 4vsKimi K2.5
Claude Sonnet 4 | Kimi K2.5 | |
|---|---|---|
| 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. | 30% | 52%Best |
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. | 72.7% | 76.8%Best |
Agentic coding CursorBench v3.1Cursor's own test of harder, real-world coding tasks inside a code editor. Higher is better. | — | 31.9% |
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. | — | 21% |
Competitive coding LiveCodeBenchCoding problems published so recently the AI can't have seen them in training — a contamination-free test of raw programming skill. Higher is better. | — | 85% |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 75.4% | 87.6%Best |
Community preference (code) Arena Elo (Code)Like the text arena, but people vote on which AI writes better code. The votes become a chess-style Elo rating on arena.ai. Higher is better. | — | 1433 |
| Overview | ||
| Company | Anthropic | Moonshot AI |
| Release date | May 22 2025 | Jan 27 2026 |
| Access | Proprietary | Open Weight |
Which is better: Claude Sonnet 4 or Kimi K2.5?
Kimi K2.5 leads Claude Sonnet 4 on 3 of the 3 benchmarks they both report (BullshitBench v2, SWE-Bench Verified, GPQA Diamond). Claude Sonnet 4 shipped 250 days before Kimi K2.5, so benchmark comparisons should account for the intervening progress.
Claude Sonnet 4 is proprietary, while Kimi K2.5 is open weight.
On BullshitBench v2, Kimi K2.5 leads at 52% vs Claude Sonnet 4 at 30%. On SWE-Bench Verified, Kimi K2.5 leads at 76.8% vs Claude Sonnet 4 at 72.7%. On GPQA Diamond, Kimi K2.5 leads at 87.6% vs Claude Sonnet 4 at 75.4%.
Frequently asked questions
Claude Sonnet 4 was released by Anthropic on May 22 2025.
Kimi K2.5 was released by Moonshot AI on Jan 27 2026.
Kimi K2.5 leads on SWE-Bench Verified — Claude Sonnet 4 72.7% vs Kimi K2.5 76.8%.
Kimi K2.5 leads on GPQA Diamond — Claude Sonnet 4 75.4% vs Kimi K2.5 87.6%.
Claude Sonnet 4 is a proprietary model released by Anthropic. Kimi K2.5 is an open weight model released by Moonshot AI.