Claude 3.7 Sonnet Pro vs Kimi K2 Chat: which model should you choose?
We compared Claude 3.7 Sonnet Pro and Kimi K2 Chat on price, context window and 12 benchmarks. Claude 3.7 Sonnet Pro has the stronger average benchmark score; Kimi K2 Chat is cheaper on a blended 3:1 basis.
Claude 3.7 Sonnet Pro
Claude 3.7 Sonnet Pro is a frontier model from Anthropic. It offers a 128,000-token context window, costs $16.07 per million input tokens and $85.28 per million output tokens, and averages 83.3 across the index's benchmark suite.
- Input
- $16.07 / 1M
- Output
- $85.28 / 1M
- Context
- 128,000
- Avg score
- 83.3
- Open weights
- No
Kimi K2 Chat
Kimi K2 Chat is a multimodal model from Moonshot AI. It offers a 400,000-token context window, costs $5.74 per million input tokens and $22.24 per million output tokens, and averages 82.1 across the index's benchmark suite.
- Input
- $5.74 / 1M
- Output
- $22.24 / 1M
- Context
- 400,000
- Avg score
- 82.1
- Open weights
- Yes
Specification comparison
| Spec | Claude 3.7 Sonnet Pro | Kimi K2 Chat | Edge |
|---|---|---|---|
| Input price / 1M | $16.07 | $5.74 | B |
| Output price / 1M | $85.28 | $22.24 | B |
| Context window | 128,000 | 400,000 | B |
| Max output | 8,192 | 4,096 | A |
| Average score | 83.3 | 82.1 | A |
| Arena Elo | 1446.8 | 1445.6 | A |
| Open weights | No | Yes | B |
Benchmark comparison
Claude 3.7 Sonnet Pro wins 9, Kimi K2 Chat wins 3, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude 3.7 Sonnet Pro | Kimi K2 Chat | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 85.7 | 82.7 | 3.0 | Claude 3.7 Sonnet Pro |
| GPQA Diamond | 80.6 | 77.4 | 3.2 | Claude 3.7 Sonnet Pro |
| SWE-bench Verified | 71.4 | 70.0 | 1.4 | Claude 3.7 Sonnet Pro |
| HumanEval | 90.0 | 88.1 | 1.9 | Claude 3.7 Sonnet Pro |
| MATH-500 | 89.2 | 84.8 | 4.4 | Claude 3.7 Sonnet Pro |
| AIME 2025 | 81.5 | 84.1 | 2.6 | Kimi K2 Chat |
| LiveCodeBench | 74.1 | 74.5 | 0.4 | Kimi K2 Chat |
| IFEval | 88.5 | 88.0 | 0.5 | Claude 3.7 Sonnet Pro |
| TruthfulQA | 86.0 | 82.8 | 3.2 | Claude 3.7 Sonnet Pro |
| HellaSwag | 89.7 | 91.6 | 1.9 | Kimi K2 Chat |
| MMMU | 79.7 | 79.6 | 0.1 | Claude 3.7 Sonnet Pro |
| Arena Elo | 1446.8 | 1445.6 | 1.2 | Claude 3.7 Sonnet Pro |
Price analysis
On a blended 3:1 input-to-output basis, Claude 3.7 Sonnet Pro costs about $33.37 per million tokens and Kimi K2 Chat costs about $9.86. Kimi K2 Chat is roughly 70% cheaper than Claude 3.7 Sonnet Pro. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Kimi K2 Chat has the larger context window at 400,000 tokens, compared with 128,000 for Claude 3.7 Sonnet Pro. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude 3.7 Sonnet Pro wins 9, Kimi K2 Chat wins 3, and 0 are tied. On the index average, Claude 3.7 Sonnet Pro leads Kimi K2 Chat by 1.2 points (83.3 versus 82.1).
The price picture favours Kimi K2 Chat. The context picture favours Kimi K2 Chat. Those two dimensions often matter more than a few benchmark points once a model is good enough for the task.
If you need a single default, start with Claude 3.7 Sonnet Pro for quality-sensitive work and Kimi K2 Chat for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose Claude 3.7 Sonnet Pro if
- You want the higher average benchmark score in this index.
- You need the larger 8,192-token output limit.
Choose Kimi K2 Chat if
- Unit cost matters and you want the cheaper blended price.
- You need the larger 400,000-token context window.
- You need open weights for self-hosting or fine-tuning.
FAQ
Is Claude 3.7 Sonnet Pro better than Kimi K2 Chat?
On the index average, Claude 3.7 Sonnet Pro leads Kimi K2 Chat by 1.2 points (83.3 versus 82.1). The better choice depends on price, context and your task. Claude 3.7 Sonnet Pro wins 9 benchmarks, Kimi K2 Chat wins 3.
Which is cheaper, Claude 3.7 Sonnet Pro or Kimi K2 Chat?
Kimi K2 Chat is cheaper on a blended 3:1 basis at about $9.86 per million tokens, versus $33.37 for Claude 3.7 Sonnet Pro.
Which has the larger context window?
Kimi K2 Chat has the larger context window at 400,000 tokens. Claude 3.7 Sonnet Pro has 128,000 tokens.
Are these models open weights?
Claude 3.7 Sonnet Pro is proprietary; Kimi K2 Chat is open weights.
Which should I choose for production?
If you need a single default, start with Claude 3.7 Sonnet Pro for quality-sensitive work and Kimi K2 Chat for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.