GPT-4.1 vs Kimi K2 Chat: which model should you choose?
We compared GPT-4.1 and Kimi K2 Chat on price, context window and 12 benchmarks. GPT-4.1 has the stronger average benchmark score; Kimi K2 Chat is cheaper on a blended 3:1 basis.
GPT-4.1
GPT-4.1 is a multimodal model from OpenAI. It offers a 1,000,000-token context window, costs $15.71 per million input tokens and $64.52 per million output tokens, and averages 82.4 across the index's benchmark suite.
- Input
- $15.71 / 1M
- Output
- $64.52 / 1M
- Context
- 1,000,000
- Avg score
- 82.4
- 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 | GPT-4.1 | Kimi K2 Chat | Edge |
|---|---|---|---|
| Input price / 1M | $15.71 | $5.74 | B |
| Output price / 1M | $64.52 | $22.24 | B |
| Context window | 1,000,000 | 400,000 | A |
| Max output | 16,384 | 4,096 | A |
| Average score | 82.4 | 82.1 | A |
| Arena Elo | 1432.4 | 1445.6 | B |
| Open weights | No | Yes | B |
Benchmark comparison
GPT-4.1 wins 6, Kimi K2 Chat wins 6, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | GPT-4.1 | Kimi K2 Chat | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 86.2 | 82.7 | 3.5 | GPT-4.1 |
| GPQA Diamond | 76.1 | 77.4 | 1.3 | Kimi K2 Chat |
| SWE-bench Verified | 72.2 | 70.0 | 2.2 | GPT-4.1 |
| HumanEval | 88.3 | 88.1 | 0.2 | GPT-4.1 |
| MATH-500 | 86.8 | 84.8 | 2.0 | GPT-4.1 |
| AIME 2025 | 79.9 | 84.1 | 4.2 | Kimi K2 Chat |
| LiveCodeBench | 77.8 | 74.5 | 3.3 | GPT-4.1 |
| IFEval | 90.4 | 88.0 | 2.4 | GPT-4.1 |
| TruthfulQA | 81.8 | 82.8 | 1.0 | Kimi K2 Chat |
| HellaSwag | 90.3 | 91.6 | 1.3 | Kimi K2 Chat |
| MMMU | 76.3 | 79.6 | 3.3 | Kimi K2 Chat |
| Arena Elo | 1432.4 | 1445.6 | 13.2 | Kimi K2 Chat |
Price analysis
On a blended 3:1 input-to-output basis, GPT-4.1 costs about $27.91 per million tokens and Kimi K2 Chat costs about $9.86. Kimi K2 Chat is roughly 65% cheaper than GPT-4.1. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
GPT-4.1 has the larger context window at 1,000,000 tokens, compared with 400,000 for Kimi K2 Chat. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, GPT-4.1 wins 6, Kimi K2 Chat wins 6, and 0 are tied. On the index average, GPT-4.1 leads Kimi K2 Chat by 0.3 points (82.4 versus 82.1).
The price picture favours Kimi K2 Chat. The context picture favours GPT-4.1. 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 GPT-4.1 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 GPT-4.1 if
- You want the higher average benchmark score in this index.
- You need the larger 1,000,000-token context window.
- You need the larger 16,384-token output limit.
Choose Kimi K2 Chat if
- Unit cost matters and you want the cheaper blended price.
- You need open weights for self-hosting or fine-tuning.
FAQ
Is GPT-4.1 better than Kimi K2 Chat?
On the index average, GPT-4.1 leads Kimi K2 Chat by 0.3 points (82.4 versus 82.1). The better choice depends on price, context and your task. GPT-4.1 wins 6 benchmarks, Kimi K2 Chat wins 6.
Which is cheaper, GPT-4.1 or Kimi K2 Chat?
Kimi K2 Chat is cheaper on a blended 3:1 basis at about $9.86 per million tokens, versus $27.91 for GPT-4.1.
Which has the larger context window?
GPT-4.1 has the larger context window at 1,000,000 tokens. Kimi K2 Chat has 400,000 tokens.
Are these models open weights?
GPT-4.1 is proprietary; Kimi K2 Chat is open weights.
Which should I choose for production?
If you need a single default, start with GPT-4.1 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.