GPT-5.1 Chat vs Kimi K2 Thinking
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for GPT-5.1 Chat and Kimi K2 Thinking.
GPT-5.1 Chat
GPT-5.1 Chat (AKA Instant is the fast, lightweight member of the 5.1 family, optimized for low-latency chat while retaining strong general intelligence. It uses adaptive reasoning to selectively “think” on...
Kimi K2 Thinking
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...
Technical Specifications
| Specification | GPT-5.1 Chat | Kimi K2 Thinking |
|---|---|---|
| Provider | OpenAI | Moonshot AI |
| Context Window | 128,000 tokens | 262,144 tokens |
| Agent Suitability | N/A | N/A |
| Time to First Token (TTFT) | N/A | N/A |
| Deployment Model | managed api | managed api |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2025-11-13 | 2025-11-06 |
API Pricing Comparison
Input Price per Million Tokens
GPT-5.1 Chat
$1.25
Kimi K2 Thinking
$0.60
Output Price per Million Tokens
GPT-5.1 Chat
$10.00
Kimi K2 Thinking
$2.50
Want to test both models live?
Run side-by-side prompt prompts in our dynamic Sandbox. Check execution speeds, latency metrics, and compute actual costs in real-time.
Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
GPT-5.1 Chat Quirks & Gotchas
No developer gotchas reported.
Kimi K2 Thinking Quirks & Gotchas
No developer gotchas reported.