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Claude Sonnet 5.5 vs Kimi K2-Instruct-0905

Claude Sonnet 5.5 leads the LLM Stats Score 58.0 to 21.6.

Anthropic · Moonshot AI · Updated for 2026

Which is better?

Claude Sonnet 5.5 leads the overall LLM Stats Score 58.0 to 21.6, ranking #3 overall.

In the 1 individual benchmarks reported for both models, Claude Sonnet 5.5 wins 1; 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 Claude Sonnet 5.5

  • overall performance matters — it scores 58.0 and ranks #3 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you value its reported benchmark strengths — it wins 1 of 1 exact shared results
  • you want the most recent training data — it shipped Sep 2026

Choose Kimi K2-Instruct-0905

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

At a glance

The differences that matter most.

Claude Sonnet 5.5
Anthropic
Kimi K2-Instruct-0905
Moonshot AI
Core performance indexes
LLM Stats Score
58.0
#3
21.6
#194
Reasoning
56.6
#3
21.8
#184
Coding
48.8
#2
9.7
#177
Agents
42.3
#3
-4.2
#188
Cost, coverage & limits
Benchmark wins
1 of 1
0 of 1
Input price
$2.00 / M
— / M
Output price
$10.00 / M
— / M
Context window
1,000,000
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

2 shared
Index
Claude Sonnet 5.5
Kimi K2-Instruct-0905
Math
36.9#34
21.5#146
Tool use
34.0#2
6.4#150
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

47 reported for Claude Sonnet 5.5 · 29 for Kimi K2-Instruct-0905

1 shared

Claude Sonnet 5.5 outperforms in 1 benchmarks (SWE-bench Multilingual), while Kimi K2-Instruct-0905 is better at 0 benchmarks.

Claude Sonnet 5.5 significantly outperforms across most benchmarks.

Fri Oct 02 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Context Window

Maximum input and output token capacity

Only Claude Sonnet 5.5 specifies input context (1,000,000 tokens). Only Claude Sonnet 5.5 specifies output context (128,000 tokens).

Anthropic
Claude Sonnet 5.5
Input1,000,000 tokens
Output128,000 tokens
Moonshot AI
Kimi K2-Instruct-0905
Input- tokens
Output- tokens
Fri Oct 02 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Claude Sonnet 5.5 supports multimodal inputs, whereas Kimi K2-Instruct-0905 does not.

Claude Sonnet 5.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Claude Sonnet 5.5

Text
Images
Audio
Video

Kimi K2-Instruct-0905

Text
Images
Audio
Video

License

Usage and distribution terms

Claude Sonnet 5.5 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.

Claude Sonnet 5.5

Proprietary

Closed source

Kimi K2-Instruct-0905

MIT

Open weights

Release Timeline

When each model was launched

Claude Sonnet 5.5 was released on 2026-09-28, while Kimi K2-Instruct-0905 was released on 2025-09-05.

Claude Sonnet 5.5 is 13 months newer than Kimi K2-Instruct-0905.

Claude Sonnet 5.5

Sep 28, 2026

4 days ago

1.1yr newer
Kimi K2-Instruct-0905

Sep 5, 2025

1.1 years ago

Knowledge Cutoff

When training data ends

Claude Sonnet 5.5 has a documented knowledge cutoff of 2026-06-01, while Kimi K2-Instruct-0905's cutoff date is not specified.

We can confirm Claude Sonnet 5.5's training data extends to 2026-06-01, but cannot make a direct comparison without Kimi K2-Instruct-0905's cutoff date.

Claude Sonnet 5.5

Jun 2026

Kimi K2-Instruct-0905

—

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against Claude Sonnet 5.5 and Kimi K2-Instruct-0905 side-by-side, then vote on the output you prefer.

Claude Sonnet 5.5
✓ Preferred
Kimi K2-Instruct-0905
Open in Playground

FAQ

Common questions about Claude Sonnet 5.5 vs Kimi K2-Instruct-0905.

Which is better, Claude Sonnet 5.5 or Kimi K2-Instruct-0905?

Claude Sonnet 5.5 leads the LLM Stats Score 58.0 to 21.6. Claude Sonnet 5.5 is made by Anthropic 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 Claude Sonnet 5.5 compare to Kimi K2-Instruct-0905 in benchmarks?

Claude Sonnet 5.5 scores BenchCAD (with Python tool): 96.3%, ArXivMath (with tools): 95.2%, Global-MMLU: 92.1%, MILU: 91.6%, SWE-bench Multilingual: 90.3%. 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 Claude Sonnet 5.5 and Kimi K2-Instruct-0905?

Claude Sonnet 5.5 supports 1.0M 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 Claude Sonnet 5.5 and Kimi K2-Instruct-0905?

Key differences include LLM Stats Score (58.0 vs 21.6), multimodal support (yes vs no), licensing (Proprietary vs MIT). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Sonnet 5.5 and Kimi K2-Instruct-0905?

Claude Sonnet 5.5 is developed by Anthropic and Kimi K2-Instruct-0905 is developed by Moonshot AI.

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