Model Comparison

GPT-5.6 Luna vs Kimi K2-Instruct-0905Which is better in 2026?

GPT-5.6 Luna significantly outperforms across most benchmarks.

Verdict: GPT-5.6 Luna vs Kimi K2-Instruct-0905 — which is better?

GPT-5.6 Luna (by OpenAI) and Kimi K2-Instruct-0905 (by Moonshot AI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

GPT-5.6 Luna outperforms in 1 benchmarks (GPQA), while Kimi K2-Instruct-0905 is better at 0 benchmarks. GPT-5.6 Luna significantly outperforms across most benchmarks.

Choose GPT-5.6 Luna if…

  • you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
  • you want the most recent training data — it shipped Jul 2026

Choose Kimi K2-Instruct-0905 if…

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

Performance Benchmarks

Comparative analysis across standard metrics

1 benchmarks

GPT-5.6 Luna outperforms in 1 benchmarks (GPQA), while Kimi K2-Instruct-0905 is better at 0 benchmarks.

GPT-5.6 Luna significantly outperforms across most benchmarks.

Tue Jul 21 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only GPT-5.6 Luna specifies input context (1,050,000 tokens). Only GPT-5.6 Luna specifies output context (128,000 tokens).

OpenAI
GPT-5.6 Luna
Input1,050,000 tokens
Output128,000 tokens
Moonshot AI
Kimi K2-Instruct-0905
Input- tokens
Output- tokens
Tue Jul 21 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

GPT-5.6 Luna supports multimodal inputs, whereas Kimi K2-Instruct-0905 does not.

GPT-5.6 Luna can handle both text and other forms of data like images, making it suitable for multimodal applications.

GPT-5.6 Luna

Text
Images
Audio
Video

Kimi K2-Instruct-0905

Text
Images
Audio
Video

License

Usage and distribution terms

GPT-5.6 Luna 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-5.6 Luna

Proprietary

Closed source

Kimi K2-Instruct-0905

MIT

Open weights

Release Timeline

When each model was launched

GPT-5.6 Luna was released on 2026-07-09, while Kimi K2-Instruct-0905 was released on 2025-09-05.

GPT-5.6 Luna is 10 months newer than Kimi K2-Instruct-0905.

GPT-5.6 Luna

Jul 9, 2026

1 weeks ago

10mo newer
Kimi K2-Instruct-0905

Sep 5, 2025

10 months ago

Knowledge Cutoff

When training data ends

GPT-5.6 Luna has a documented knowledge cutoff of 2026-02-16, while Kimi K2-Instruct-0905's cutoff date is not specified.

We can confirm GPT-5.6 Luna's training data extends to 2026-02-16, but cannot make a direct comparison without Kimi K2-Instruct-0905's cutoff date.

GPT-5.6 Luna

Feb 2026

Kimi K2-Instruct-0905

—

Outputs Comparison

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Key Takeaways

OpenAI
Larger context window (1,050,000 tokens)
Supports multimodal inputs
Higher GPQA score (92.3% vs 75.1%)
Moonshot AI
Has open weights

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against GPT-5.6 Luna and Kimi K2-Instruct-0905 side-by-side, then vote on the output you prefer.

GPT-5.6 Luna
✓ Preferred
Kimi K2-Instruct-0905
Open in Playground
AI Model Comparison Table
Feature
OpenAI
GPT-5.6 Luna
Moonshot AI
Kimi K2-Instruct-0905

FAQ

Common questions about GPT-5.6 Luna vs Kimi K2-Instruct-0905.

Which is better, GPT-5.6 Luna or Kimi K2-Instruct-0905?

GPT-5.6 Luna significantly outperforms across most benchmarks. GPT-5.6 Luna is made by OpenAI and Kimi K2-Instruct-0905 is made by Moonshot AI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does GPT-5.6 Luna compare to Kimi K2-Instruct-0905 in benchmarks?

GPT-5.6 Luna scores Connectors: 99.9%, HealthBench Consensus: 95.1%, GPQA: 92.3%, Search and Function-Calling: 89.7%, Capture-the-Flag Challenges (Internal): 85.2%. 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-5.6 Luna and Kimi K2-Instruct-0905?

GPT-5.6 Luna supports 1.1M 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-5.6 Luna and Kimi K2-Instruct-0905?

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

Who makes GPT-5.6 Luna and Kimi K2-Instruct-0905?

GPT-5.6 Luna is developed by OpenAI and Kimi K2-Instruct-0905 is developed by Moonshot AI.

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