The AI arena is free today

Open Superagent

Claude Sonnet 5.5 vs Kimi-k1.5

Claude Sonnet 5.5 leads the LLM Stats Score 58.0 to 17.2.

Anthropic · Moonshot AI · Updated for 2026

Which is better?

Claude Sonnet 5.5 leads the overall LLM Stats Score 58.0 to 17.2, ranking #3 overall.

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 — it leads those capability indexes
  • you want the most recent training data — it shipped Sep 2026

Choose Kimi-k1.5

  • you are already invested in the Moonshot AI ecosystem

At a glance

The differences that matter most.

Claude Sonnet 5.5
Anthropic
Kimi-k1.5
Moonshot AI
Core performance indexes
LLM Stats Score
58.0
#3
17.2
#226
Reasoning
56.6
#3
16.4
#223
Cost, coverage & limits
Benchmark wins
—
—
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

3 shared
Index
Claude Sonnet 5.5
Kimi-k1.5
Math
36.9#34
20.2#162
Vision
40.0#3
11.0#118
Multimodal
40.1#2
14.7#99
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

47 reported for Claude Sonnet 5.5 · 9 for Kimi-k1.5

No common benchmarks found

Claude Sonnet 5.5 and Kimi-k1.5don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

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-k1.5
Input- tokens
Output- tokens
Wed Sep 30 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Claude Sonnet 5.5 and Kimi-k1.5 support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Claude Sonnet 5.5

Text
Images
Audio
Video

Kimi-k1.5

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Claude Sonnet 5.5

Proprietary

Closed source

Kimi-k1.5

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Sonnet 5.5 was released on 2026-09-28, while Kimi-k1.5 was released on 2025-01-20.

Claude Sonnet 5.5 is 21 months newer than Kimi-k1.5.

Claude Sonnet 5.5

Sep 28, 2026

1 days ago

1.7yr newer
Kimi-k1.5

Jan 20, 2025

1.7 years ago

Knowledge Cutoff

When training data ends

Claude Sonnet 5.5 has a documented knowledge cutoff of 2026-06-01, while Kimi-k1.5'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-k1.5's cutoff date.

Claude Sonnet 5.5

Jun 2026

Kimi-k1.5

—

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against Claude Sonnet 5.5 and Kimi-k1.5 side-by-side, then vote on the output you prefer.

Claude Sonnet 5.5
✓ Preferred
Kimi-k1.5
Open in Playground

FAQ

Common questions about Claude Sonnet 5.5 vs Kimi-k1.5.

Which is better, Claude Sonnet 5.5 or Kimi-k1.5?

Claude Sonnet 5.5 leads the LLM Stats Score 58.0 to 17.2. Claude Sonnet 5.5 is made by Anthropic and Kimi-k1.5 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-k1.5 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-k1.5 scores MATH-500: 96.2%, CLUEWSC: 91.4%, C-Eval: 88.3%, MMLU: 87.4%, IFEval: 87.2%.

What are the context window sizes for Claude Sonnet 5.5 and Kimi-k1.5?

Claude Sonnet 5.5 supports 1.0M tokens and Kimi-k1.5 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-k1.5?

Key differences include LLM Stats Score (58.0 vs 17.2). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Sonnet 5.5 and Kimi-k1.5?

Claude Sonnet 5.5 is developed by Anthropic and Kimi-k1.5 is developed by Moonshot AI.

Related comparisons