Kimi K3 vs Claude Opus 5.5
Kimi K3 is from Moonshot AI, released July 16, 2026. Claude Opus 5.5 is from Anthropic, released September 22, 2026.
- LMArena Elo1488 vs 1509. Claude Opus 5.5 is 1.4% ahead on LMArena Elo.
- Input per 1M$3 vs $4. Kimi K3 costs 25% less per million input tokens.
- Output per 1M$15 vs $20. Kimi K3 costs 25% less per million output tokens.
- Context window1M vs 1M. Both hold 1M tokens of context.
Prices are the vendors’ published API rates; Elo is LMArena’s text board. Each figure is dated on its model page.
Interactive Comparison
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$3 / $15 per million tokens | $4 / $20 per million tokens | |
|---|---|---|
| Identity | ||
| Developer | Moonshot AI | Anthropic |
| Released | Jul 2026 | Sep 2026 |
| Status | GA | GA |
| Licence | Open weights (Kimi K3 License) | Proprietary |
| Self-hostable | Yes | No |
| Cost | ||
| Blended $/1M tokensinput × 0.75 + output × 0.25 | $6.000 / 1M tokens | $8.000 / 1M tokens |
| Input price | $3.000 / 1M tokens | $4.000 / 1M tokens |
| Output price | $15.000 / 1M tokens | $20.000 / 1M tokens |
| Cached input | $0.30 / 1M tokens (automatic context-cache hit; $3.00 on a cache miss) | $0.20 per 1M tokens |
| Batch discount | Not offered | 50% ($2 / $10 per 1M tokens) |
| Free tier | Not offered | — |
| Capacity | ||
| Context window | 1M tokens | 1M tokens |
| Max output | 128k tokens (default; max_completion_tokens configurable up to 1M) | 128k tokens |
| Long-context surcharge | None (flat rate across the 1M window) | — |
| Capability | ||
| Vision in | Yes | Yes |
| Audio in | No | No |
| Function calling | Yes | Yes |
| Structured output | Yes | Yes |
| Extended reasoning | Yes | Yes |
| Web search | Yes (tool currently being updated by Moonshot; not recommended for near-term use) | Yes |
| Code execution | Not offered | Yes |
| Access | ||
| API | Yes | Yes |
| Chat app | Yes | Yes |
| Cloud marketplaces | Azure AI Foundry (via Fireworks AI), OpenRouter | Amazon Bedrock, Google Cloud, Microsoft Foundry |
| Fine-tuning | Not offered | No |
| Measured quality | ||
| LMArena Elo | 1488 (checked Nov 2026) | 1509 (checked Nov 2026) |
| LMArena rank | Rank 19 | Rank 3 |
| GPQA Diamond | 93 | 91 · max effort |
| Elo per dollarLMArena Elo ÷ blended $/1M tokens | 248 | 189 |
