Kimi K1.5 Chat vs Sonar Pro Reasoning: which model should you choose?
We compared Kimi K1.5 Chat and Sonar Pro Reasoning on price, context window and 12 benchmarks. Sonar Pro Reasoning has the stronger average benchmark score; Kimi K1.5 Chat is cheaper on a blended 3:1 basis.
Kimi K1.5 Chat
Kimi K1.5 Chat is a multimodal model from Moonshot AI. It offers a 128,000-token context window, costs $5.11 per million input tokens and $26.59 per million output tokens, and averages 80.2 across the index's benchmark suite.
- Input
- $5.11 / 1M
- Output
- $26.59 / 1M
- Context
- 128,000
- Avg score
- 80.2
- Open weights
- Yes
Sonar Pro Reasoning
Sonar Pro Reasoning is a multimodal model from Perplexity. It offers a 128,000-token context window, costs $13.94 per million input tokens and $72.76 per million output tokens, and averages 80.5 across the index's benchmark suite.
- Input
- $13.94 / 1M
- Output
- $72.76 / 1M
- Context
- 128,000
- Avg score
- 80.5
- Open weights
- No
Specification comparison
| Spec | Kimi K1.5 Chat | Sonar Pro Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $5.11 | $13.94 | A |
| Output price / 1M | $26.59 | $72.76 | A |
| Context window | 128,000 | 128,000 | Tie |
| Max output | 32,768 | 32,768 | Tie |
| Average score | 80.2 | 80.5 | B |
| Arena Elo | 1422.6 | 1439.7 | B |
| Open weights | Yes | No | A |
Benchmark comparison
Kimi K1.5 Chat wins 5, Sonar Pro Reasoning wins 7, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Kimi K1.5 Chat | Sonar Pro Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 81.3 | 82.6 | 1.3 | Sonar Pro Reasoning |
| GPQA Diamond | 78.1 | 76.2 | 1.9 | Kimi K1.5 Chat |
| SWE-bench Verified | 69.9 | 71.7 | 1.8 | Sonar Pro Reasoning |
| HumanEval | 84.3 | 82.7 | 1.6 | Kimi K1.5 Chat |
| MATH-500 | 81.7 | 85.1 | 3.4 | Sonar Pro Reasoning |
| AIME 2025 | 81.4 | 73.7 | 7.7 | Kimi K1.5 Chat |
| LiveCodeBench | 75.7 | 75.6 | 0.1 | Kimi K1.5 Chat |
| IFEval | 88.2 | 87.1 | 1.1 | Kimi K1.5 Chat |
| TruthfulQA | 80.3 | 84.4 | 4.1 | Sonar Pro Reasoning |
| HellaSwag | 87.2 | 89.9 | 2.7 | Sonar Pro Reasoning |
| MMMU | 73.6 | 76.1 | 2.5 | Sonar Pro Reasoning |
| Arena Elo | 1422.6 | 1439.7 | 17.1 | Sonar Pro Reasoning |
Price analysis
On a blended 3:1 input-to-output basis, Kimi K1.5 Chat costs about $10.48 per million tokens and Sonar Pro Reasoning costs about $28.65. Kimi K1.5 Chat is roughly 63% cheaper than Sonar Pro Reasoning. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Both models list a 128,000-token context window. That is enough for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Kimi K1.5 Chat wins 5, Sonar Pro Reasoning wins 7, and 0 are tied. On the index average, Sonar Pro Reasoning leads Kimi K1.5 Chat by 0.3 points (80.5 versus 80.2).
The price picture favours Kimi K1.5 Chat. The context picture is effectively a tie. 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 Sonar Pro Reasoning for quality-sensitive work and Kimi K1.5 Chat for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose Kimi K1.5 Chat if
- Unit cost matters and you want the cheaper blended price.
- You need open weights for self-hosting or fine-tuning.
Choose Sonar Pro Reasoning if
- You want the higher average benchmark score in this index.
- The workload needs multi-step reasoning.
FAQ
Is Kimi K1.5 Chat better than Sonar Pro Reasoning?
On the index average, Sonar Pro Reasoning leads Kimi K1.5 Chat by 0.3 points (80.5 versus 80.2). The better choice depends on price, context and your task. Kimi K1.5 Chat wins 5 benchmarks, Sonar Pro Reasoning wins 7.
Which is cheaper, Kimi K1.5 Chat or Sonar Pro Reasoning?
Kimi K1.5 Chat is cheaper on a blended 3:1 basis at about $10.48 per million tokens, versus $28.65 for Sonar Pro Reasoning.
Which has the larger context window?
Both models list a 128,000-token context window.
Are these models open weights?
Kimi K1.5 Chat is open weights; Sonar Pro Reasoning is proprietary.
Which should I choose for production?
If you need a single default, start with Sonar Pro Reasoning for quality-sensitive work and Kimi K1.5 Chat for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.