Model Comparison

Grok 4.5 vs Kimi K2-Instruct-0905Which is better in 2026?

Grok 4.5 significantly outperforms across most benchmarks.

Verdict: Grok 4.5 vs Kimi K2-Instruct-0905 — which is better?

Grok 4.5 (by xAI) 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.

Grok 4.5 outperforms in 1 benchmarks (GPQA), while Kimi K2-Instruct-0905 is better at 0 benchmarks. Grok 4.5 significantly outperforms across most benchmarks.

Choose Grok 4.5 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

Grok 4.5 outperforms in 1 benchmarks (GPQA), while Kimi K2-Instruct-0905 is better at 0 benchmarks.

Grok 4.5 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 Grok 4.5 specifies input context (500,000 tokens).

xAI
Grok 4.5
Input500,000 tokens
Output- 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

Grok 4.5 supports multimodal inputs, whereas Kimi K2-Instruct-0905 does not.

Grok 4.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Grok 4.5

Text
Images
Audio
Video

Kimi K2-Instruct-0905

Text
Images
Audio
Video

License

Usage and distribution terms

Grok 4.5 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.

Grok 4.5

Proprietary

Closed source

Kimi K2-Instruct-0905

MIT

Open weights

Release Timeline

When each model was launched

Grok 4.5 was released on 2026-07-16, while Kimi K2-Instruct-0905 was released on 2025-09-05.

Grok 4.5 is 10 months newer than Kimi K2-Instruct-0905.

Grok 4.5

Jul 16, 2026

4 days ago

10mo newer
Kimi K2-Instruct-0905

Sep 5, 2025

10 months ago

Knowledge Cutoff

When training data ends

Grok 4.5 has a documented knowledge cutoff of 2026-02-01, while Kimi K2-Instruct-0905's cutoff date is not specified.

We can confirm Grok 4.5's training data extends to 2026-02-01, but cannot make a direct comparison without Kimi K2-Instruct-0905's cutoff date.

Grok 4.5

Feb 2026

Kimi K2-Instruct-0905

—

Outputs Comparison

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Key Takeaways

xAI
Larger context window (500,000 tokens)
Supports multimodal inputs
Higher GPQA score (93.0% vs 75.1%)
Moonshot AI
Has open weights

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Grok 4.5 and Kimi K2-Instruct-0905 side-by-side, then vote on the output you prefer.

Grok 4.5
✓ Preferred
Kimi K2-Instruct-0905
Open in Playground
AI Model Comparison Table
Feature
xAI
Grok 4.5
Moonshot AI
Kimi K2-Instruct-0905

FAQ

Common questions about Grok 4.5 vs Kimi K2-Instruct-0905.

Which is better, Grok 4.5 or Kimi K2-Instruct-0905?

Grok 4.5 significantly outperforms across most benchmarks. Grok 4.5 is made by xAI 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 Grok 4.5 compare to Kimi K2-Instruct-0905 in benchmarks?

Grok 4.5 scores GPQA: 93.0%, Terminal-Bench 2.1: 83.3%, Artificial Analysis Coding Agent Index v1.1: 76.0%, SWE-Bench Pro: 64.7%, AA-Omniscience Index: 63.0%. 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 Grok 4.5 and Kimi K2-Instruct-0905?

Grok 4.5 supports 500K 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 Grok 4.5 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 Grok 4.5 and Kimi K2-Instruct-0905?

Grok 4.5 is developed by xAI and Kimi K2-Instruct-0905 is developed by Moonshot AI.

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