Grok 3 Reasoning vs Kimi K2: which model should you choose?
We compared Grok 3 Reasoning and Kimi K2 on price, context window and 12 benchmarks. Kimi K2 has the stronger average benchmark score; Kimi K2 is cheaper on a blended 3:1 basis.
Grok 3 Reasoning
Grok 3 Reasoning is a frontier model from xAI. It offers a 200,000-token context window, costs $16.07 per million input tokens and $74.65 per million output tokens, and averages 82.9 across the index's benchmark suite.
- Input
- $16.07 / 1M
- Output
- $74.65 / 1M
- Context
- 200,000
- Avg score
- 82.9
- Open weights
- No
Kimi K2
Kimi K2 is a multimodal model from Moonshot AI. It offers a 128,000-token context window, costs $5.85 per million input tokens and $21.72 per million output tokens, and averages 83.0 across the index's benchmark suite.
- Input
- $5.85 / 1M
- Output
- $21.72 / 1M
- Context
- 128,000
- Avg score
- 83.0
- Open weights
- Yes
Specification comparison
| Spec | Grok 3 Reasoning | Kimi K2 | Edge |
|---|---|---|---|
| Input price / 1M | $16.07 | $5.85 | B |
| Output price / 1M | $74.65 | $21.72 | B |
| Context window | 200,000 | 128,000 | A |
| Max output | 16,384 | 65,536 | B |
| Average score | 82.9 | 83.0 | B |
| Arena Elo | 1448.0 | 1458.5 | B |
| Open weights | No | Yes | B |
Benchmark comparison
Grok 3 Reasoning wins 5, Kimi K2 wins 7, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Grok 3 Reasoning | Kimi K2 | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 84.5 | 83.3 | 1.2 | Grok 3 Reasoning |
| GPQA Diamond | 77.3 | 77.5 | 0.2 | Kimi K2 |
| SWE-bench Verified | 74.0 | 70.2 | 3.8 | Grok 3 Reasoning |
| HumanEval | 88.5 | 87.1 | 1.4 | Grok 3 Reasoning |
| MATH-500 | 90.2 | 85.3 | 4.9 | Grok 3 Reasoning |
| AIME 2025 | 78.2 | 85.1 | 6.9 | Kimi K2 |
| LiveCodeBench | 76.5 | 78.5 | 2.0 | Kimi K2 |
| IFEval | 90.2 | 91.5 | 1.3 | Kimi K2 |
| TruthfulQA | 83.4 | 84.8 | 1.4 | Kimi K2 |
| HellaSwag | 89.7 | 92.3 | 2.6 | Kimi K2 |
| MMMU | 79.4 | 77.5 | 1.9 | Grok 3 Reasoning |
| Arena Elo | 1448.0 | 1458.5 | 10.5 | Kimi K2 |
Price analysis
On a blended 3:1 input-to-output basis, Grok 3 Reasoning costs about $30.72 per million tokens and Kimi K2 costs about $9.82. Kimi K2 is roughly 68% cheaper than Grok 3 Reasoning. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Grok 3 Reasoning has the larger context window at 200,000 tokens, compared with 128,000 for Kimi K2. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Grok 3 Reasoning wins 5, Kimi K2 wins 7, and 0 are tied. On the index average, Kimi K2 leads Grok 3 Reasoning by 0.1 points (83.0 versus 82.9).
The price picture favours Kimi K2. The context picture favours Grok 3 Reasoning. 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 Kimi K2 for quality-sensitive work, and check whether its price holds at your expected volume before committing.
Choose Grok 3 Reasoning if
- You need the larger 200,000-token context window.
Choose Kimi K2 if
- You want the higher average benchmark score in this index.
- Unit cost matters and you want the cheaper blended price.
- You need the larger 65,536-token output limit.
- You need open weights for self-hosting or fine-tuning.
FAQ
Is Grok 3 Reasoning better than Kimi K2?
On the index average, Kimi K2 leads Grok 3 Reasoning by 0.1 points (83.0 versus 82.9). The better choice depends on price, context and your task. Grok 3 Reasoning wins 5 benchmarks, Kimi K2 wins 7.
Which is cheaper, Grok 3 Reasoning or Kimi K2?
Kimi K2 is cheaper on a blended 3:1 basis at about $9.82 per million tokens, versus $30.72 for Grok 3 Reasoning.
Which has the larger context window?
Grok 3 Reasoning has the larger context window at 200,000 tokens. Kimi K2 has 128,000 tokens.
Are these models open weights?
Grok 3 Reasoning is proprietary; Kimi K2 is open weights.
Which should I choose for production?
If you need a single default, start with Kimi K2 for quality-sensitive work, and check whether its price holds at your expected volume before committing.