Grok 4.1 Fast vs Kimi K2 Thinking
Benchmarks, API pricing and specs, head to head. Data updated 2026-06-10.
xAI · Nov 2025
A 2M-token context window for $0.20 per million input tokens — the cheapest long-context frontier offering anywhere.
Moonshot AI · Nov 2025
A trillion-parameter open reasoning agent that can chain 200–300 tool calls — the open-weights agentic standout of late 2025.
The verdict
These two models don't yet share verified results on the benchmarks we track, so judge them on specs, pricing and intended use. On price the gap is dramatic: Grok 4.1 Fast works out roughly 3.9x cheaper per blended million tokens. Grok 4.1 Fast also takes 2M of context versus 262K for Kimi K2 Thinking. And Kimi K2 Thinking is open-weights (Modified MIT), so it can be self-hosted — a structural advantage if data control or vendor independence matters.
Specs & pricing
| Grok 4.1 Fast | Kimi K2 Thinking | |
|---|---|---|
| modhub Index | — | 67.6 |
| Input price / 1M | $0.2 | $0.6 |
| Output price / 1M | $0.5 | $2.5 |
| Context window | 2M | 262K |
| Max output | — | — |
| Open weights | no | yes (Modified MIT) |
| Reasoning model | yes | yes |
| Multimodal input | text, image | text |
| Knowledge cutoff | Nov 2025 | Apr 2025 |
| Released | Nov 2025 | Nov 2025 |
| Example monthly cost* | $2.75 | $9.75 |
* 10M input + 1.5M output tokens per month at list prices, no caching. Green = better value on that row.
Frequently asked questions
- Which is better, Grok 4.1 Fast or Kimi K2 Thinking?
- These two models don't yet share verified results on the benchmarks we track, so judge them on specs, pricing and intended use. On price the gap is dramatic: Grok 4.1 Fast works out roughly 3.9x cheaper per blended million tokens. Grok 4.1 Fast also takes 2M of context versus 262K for Kimi K2 Thinking. And Kimi K2 Thinking is open-weights (Modified MIT), so it can be self-hosted — a structural advantage if data control or vendor independence matters.
- Which is cheaper, Grok 4.1 Fast or Kimi K2 Thinking?
- Grok 4.1 Fast costs $0.2/$0.5 per million input/output tokens, while Kimi K2 Thinking costs $0.6/$2.5. For a typical workload of 10M input and 1.5M output tokens per month, that's $2.75 versus $9.75.
- Which model is better for coding, Grok 4.1 Fast or Kimi K2 Thinking?
- We don't yet track SWE-bench Verified results for both models; check their individual pages for coding-related scores.