Moonshot AI Kimi K1.5 vs Moonshot AI Kimi K2 (0905) — side-by-side specs.
Moonshot AI Kimi K1.5 | Moonshot AI Kimi K2 (0905) | |
|---|---|---|
| Overview | ||
| Company | Moonshot AI | Moonshot AI |
| Release date | Jan 20 2025 | Sep 5 2025 |
| Model type | — | — |
| Open source | No | Yes |
| Specifications | ||
Parameters | — | 1T |
Context window | 128k | 256k |
| Benchmarks | ||
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. | — | 65.8% |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | — | 75.1% |
| Timeline | ||
| Release gap | Kimi K1.5 shipped 228 days before Kimi K2 (0905) | |
Kimi K1.5 and Kimi K2 (0905) don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Kimi K1.5 shipped 228 days before Kimi K2 (0905), so benchmark comparisons should account for the intervening progress.
Context windows are 128k (Kimi K1.5) vs 256k (Kimi K2 (0905)). Kimi K2 (0905) is an open-source / open-weight model; Kimi K1.5 is proprietary.
Direct benchmark comparisons are unavailable — Kimi K1.5 and Kimi K2 (0905) don't publish scores on any of the same benchmarks.