Kimi K2 Thinking is Moonshot AI’s most advanced open reasoning model to date, extending the K2 series into agentic, long-horizon reasoning. Built on the trillion-parameter Mixture-of-Experts (MoE) architecture introduced in...
Model details →MoonshotAI: Kimi K2 Thinking vs OpenAI: GPT-5.1
MoonshotAI: Kimi K2 Thinking and OpenAI: GPT-5.1 are evenly matched on 6 axes — pick the one whose provider, latency, or licensing fits your stack.
GPT-5.1 is the latest frontier-grade model in the GPT-5 series, offering stronger general-purpose reasoning, improved instruction adherence, and a more natural conversational style compared to GPT-5. It uses adaptive reasoning...
Model details →Side-by-side comparison
| Capability | MoonshotAI: Kimi K2 Thinking | OpenAI: GPT-5.1 | Winner |
|---|---|---|---|
| Context window Maximum number of input tokens the model can attend to in a single request. | 262K | 400K | 🏆 OpenAI: GPT-5.1 |
| Input price (per 1M) Cost per million input tokens billed by the provider. | $0.60 | $1.25 | 🏆 MoonshotAI: Kimi K2 Thinking |
| Output price (per 1M) Cost per million output tokens billed by the provider. | $2.50 | $10.00 | 🏆 MoonshotAI: Kimi K2 Thinking |
| Tool / function calling First-class support for emitting structured tool calls. | Yes | Yes | Tie |
| Vision input Accepts image inputs alongside text. | — | Yes | 🏆 OpenAI: GPT-5.1 |
| Reasoning mode Internal chain-of-thought / extended-thinking support. | Yes | Yes | Tie |
Frequently asked questions
Is MoonshotAI: Kimi K2 Thinking better than OpenAI: GPT-5.1?
MoonshotAI: Kimi K2 Thinking and OpenAI: GPT-5.1 are evenly matched on 6 axes — pick the one whose provider, latency, or licensing fits your stack.
What's the price difference between MoonshotAI: Kimi K2 Thinking and OpenAI: GPT-5.1?
Input: $0.60 vs $1.25 per 1M tokens. Output: $2.50 vs $10.00 per 1M tokens.
What context windows do MoonshotAI: Kimi K2 Thinking and OpenAI: GPT-5.1 support?
MoonshotAI: Kimi K2 Thinking supports up to 262K tokens. OpenAI: GPT-5.1 supports up to 400K tokens.
Do both MoonshotAI: Kimi K2 Thinking and OpenAI: GPT-5.1 support tool calling?
MoonshotAI: Kimi K2 Thinking: yes. OpenAI: GPT-5.1: yes.