Model Comparison

Claude Opus 4.5 vs Kimi K2 BaseWhich is better in 2026?

Claude Opus 4.5 significantly outperforms across most benchmarks.

Verdict: Claude Opus 4.5 vs Kimi K2 Base — which is better?

Claude Opus 4.5 (by Anthropic) and Kimi K2 Base (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.

Claude Opus 4.5 outperforms in 1 benchmarks (GPQA), while Kimi K2 Base is better at 0 benchmarks. Claude Opus 4.5 significantly outperforms across most benchmarks.

Choose Claude Opus 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 Nov 2025

Choose Kimi K2 Base if…

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

Comparative analysis across standard metrics

1 benchmarks

Claude Opus 4.5 outperforms in 1 benchmarks (GPQA), while Kimi K2 Base is better at 0 benchmarks.

Claude Opus 4.5 significantly outperforms across most benchmarks.

Sun Jun 07 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only Claude Opus 4.5 specifies input context (200,000 tokens). Only Claude Opus 4.5 specifies output context (64,000 tokens).

Anthropic
Claude Opus 4.5
Input200,000 tokens
Output64,000 tokens
Moonshot AI
Kimi K2 Base
Input- tokens
Output- tokens
Sun Jun 07 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Claude Opus 4.5 supports multimodal inputs, whereas Kimi K2 Base does not.

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

Claude Opus 4.5

Text
Images
Audio
Video

Kimi K2 Base

Text
Images
Audio
Video

License

Usage and distribution terms

Claude Opus 4.5 is licensed under a proprietary license, while Kimi K2 Base uses MIT.

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

Claude Opus 4.5

Proprietary

Closed source

Kimi K2 Base

MIT

Open weights

Release Timeline

When each model was launched

Claude Opus 4.5 was released on 2025-11-24, while Kimi K2 Base was released on 2025-07-11.

Claude Opus 4.5 is 5 months newer than Kimi K2 Base.

Claude Opus 4.5

Nov 24, 2025

6 months ago

4mo newer
Kimi K2 Base

Jul 11, 2025

11 months ago

Knowledge Cutoff

When training data ends

Claude Opus 4.5 has a documented knowledge cutoff of 2025-03-31, while Kimi K2 Base's cutoff date is not specified.

We can confirm Claude Opus 4.5's training data extends to 2025-03-31, but cannot make a direct comparison without Kimi K2 Base's cutoff date.

Claude Opus 4.5

Mar 2025

Kimi K2 Base

—

Outputs Comparison

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Key Takeaways

Anthropic
Larger context window (200,000 tokens)
Supports multimodal inputs
Higher GPQA score (87.0% vs 48.1%)
Moonshot AI
Has open weights

Detailed Comparison

AI Model Comparison Table
Feature
Anthropic
Claude Opus 4.5
Moonshot AI
Kimi K2 Base

FAQ

Common questions about Claude Opus 4.5 vs Kimi K2 Base.

Which is better, Claude Opus 4.5 or Kimi K2 Base?

Claude Opus 4.5 significantly outperforms across most benchmarks. Claude Opus 4.5 is made by Anthropic and Kimi K2 Base is made by Moonshot AI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Claude Opus 4.5 compare to Kimi K2 Base in benchmarks?

Claude Opus 4.5 scores Tau2 Telecom: 98.2%, MMMLU: 90.8%, Tau2 Retail: 88.9%, GPQA: 87.0%, SWE-Bench Verified: 80.9%. Kimi K2 Base scores C-Eval: 92.5%, GSM8k: 92.1%, MMLU-redux-2.0: 90.2%, MMLU: 87.8%, TriviaQA: 85.1%.

What are the context window sizes for Claude Opus 4.5 and Kimi K2 Base?

Claude Opus 4.5 supports 200K tokens and Kimi K2 Base 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 Claude Opus 4.5 and Kimi K2 Base?

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

Who makes Claude Opus 4.5 and Kimi K2 Base?

Claude Opus 4.5 is developed by Anthropic and Kimi K2 Base is developed by Moonshot AI.

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