The AI arena is free today

Open Superagent

GPT-5.1 Thinking vs Kimi K2-Instruct-0905

GPT-5.1 Thinking leads the LLM Stats Score 36.8 to 21.7.

OpenAI · Moonshot AI · Updated for 2026

Which is better?

GPT-5.1 Thinking leads the overall LLM Stats Score 36.8 to 21.7, ranking #69 overall.

In the 6 individual benchmarks reported for both models, GPT-5.1 Thinking wins 6; this is a narrower head-to-head signal than the composite indexes.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose GPT-5.1 Thinking

  • overall performance matters — it scores 36.8 and ranks #69 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you value its reported benchmark strengths — it wins 6 of 6 exact shared results
  • you want the most recent training data — it shipped Nov 2025

Choose Kimi K2-Instruct-0905

  • you need open weights you can self-host or fine-tune

At a glance

The differences that matter most.

GPT-5.1 Thinking
OpenAI
Kimi K2-Instruct-0905
Moonshot AI
Core performance indexes
LLM Stats Score
36.8
#69
21.7
#176
Reasoning
36.5
#68
22.0
#164
Coding
21.3
#85
10.0
#159
Cost, coverage & limits
Benchmark wins
6 of 6
0 of 6
Input price
$1.25 / M
— / M
Output price
$10.00 / M
— / M
Context window
400,000
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

3 shared
Index
GPT-5.1 Thinking
Kimi K2-Instruct-0905
Math
30.1#75
21.8#137
Tool use
18.4#64
7.4#135
Writing
21.8#11
11.9#59
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

9 reported for GPT-5.1 Thinking · 29 for Kimi K2-Instruct-0905

6 shared

GPT-5.1 Thinking outperforms in 6 benchmarks (AIME 2025, GPQA, SWE-Bench Verified, Tau2 Airline, Tau2 Retail, Tau2 Telecom), while Kimi K2-Instruct-0905 is better at 0 benchmarks.

GPT-5.1 Thinking significantly outperforms across most benchmarks.

Sun Sep 06 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Context Window

Maximum input and output token capacity

Only GPT-5.1 Thinking specifies input context (400,000 tokens). Only GPT-5.1 Thinking specifies output context (128,000 tokens).

OpenAI
GPT-5.1 Thinking
Input400,000 tokens
Output128,000 tokens
Moonshot AI
Kimi K2-Instruct-0905
Input- tokens
Output- tokens
Sun Sep 06 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

GPT-5.1 Thinking supports multimodal inputs, whereas Kimi K2-Instruct-0905 does not.

GPT-5.1 Thinking can handle both text and other forms of data like images, making it suitable for multimodal applications.

GPT-5.1 Thinking

Text
Images
Audio
Video

Kimi K2-Instruct-0905

Text
Images
Audio
Video

License

Usage and distribution terms

GPT-5.1 Thinking is licensed under a proprietary license, while Kimi K2-Instruct-0905 uses MIT.

License differences may affect how you can use these models in commercial or open-source projects.

GPT-5.1 Thinking

Proprietary

Closed source

Kimi K2-Instruct-0905

MIT

Open weights

Release Timeline

When each model was launched

GPT-5.1 Thinking was released on 2025-11-12, while Kimi K2-Instruct-0905 was released on 2025-09-05.

GPT-5.1 Thinking is 2 months newer than Kimi K2-Instruct-0905.

GPT-5.1 Thinking

Nov 12, 2025

9 months ago

2mo newer
Kimi K2-Instruct-0905

Sep 5, 2025

1.0 years ago

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against GPT-5.1 Thinking and Kimi K2-Instruct-0905 side-by-side, then vote on the output you prefer.

GPT-5.1 Thinking
✓ Preferred
Kimi K2-Instruct-0905
Open in Playground

FAQ

Common questions about GPT-5.1 Thinking vs Kimi K2-Instruct-0905.

Which is better, GPT-5.1 Thinking or Kimi K2-Instruct-0905?

GPT-5.1 Thinking leads the LLM Stats Score 36.8 to 21.7. GPT-5.1 Thinking is made by OpenAI and Kimi K2-Instruct-0905 is made by Moonshot AI. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does GPT-5.1 Thinking compare to Kimi K2-Instruct-0905 in benchmarks?

GPT-5.1 Thinking scores Tau2 Telecom: 95.6%, AIME 2025: 94.0%, BrowseComp Long Context 128k: 90.0%, GPQA: 88.1%, MMMU: 85.4%. Kimi K2-Instruct-0905 scores MATH-500: 97.4%, MMLU-Redux: 92.7%, IFEval: 89.8%, AutoLogi: 89.5%, MMLU: 89.5%.

What are the context window sizes for GPT-5.1 Thinking and Kimi K2-Instruct-0905?

GPT-5.1 Thinking supports 400K tokens and Kimi K2-Instruct-0905 supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT-5.1 Thinking and Kimi K2-Instruct-0905?

Key differences include LLM Stats Score (36.8 vs 21.7), multimodal support (yes vs no), licensing (Proprietary vs MIT). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT-5.1 Thinking and Kimi K2-Instruct-0905?

GPT-5.1 Thinking is developed by OpenAI and Kimi K2-Instruct-0905 is developed by Moonshot AI.

Related comparisons