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Claude Mythos 5.1 vs Kimi K2 Base

Claude Mythos 5.1 leads the LLM Stats Score 45.1 to 13.6.

Anthropic · Moonshot AI · Updated for 2026

Which is better?

Claude Mythos 5.1 leads the overall LLM Stats Score 45.1 to 13.6, ranking #31 overall.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Claude Mythos 5.1

  • overall performance matters — it scores 45.1 and ranks #31 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 K2 Base

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

At a glance

The differences that matter most.

Claude Mythos 5.1
Anthropic
Kimi K2 Base
Moonshot AI
Core performance indexes
LLM Stats Score
45.1
#31
13.6
#242
Reasoning
44.4
#34
12.7
#240
Coding
37.5
#17
10.6
#161
Cost, coverage & limits
Benchmark wins
—
—
Input price
$10.00 / M
— / M
Output price
$50.00 / M
— / M
Context window
1,000,000
—

Individual benchmarks

1 reported for Claude Mythos 5.1 · 13 for Kimi K2 Base

No common benchmarks found

Claude Mythos 5.1 and Kimi K2 Basedon'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 Mythos 5.1 specifies input context (1,000,000 tokens). Only Claude Mythos 5.1 specifies output context (128,000 tokens).

Anthropic
Claude Mythos 5.1
Input1,000,000 tokens
Output128,000 tokens
Moonshot AI
Kimi K2 Base
Input- tokens
Output- tokens
Wed Sep 09 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Claude Mythos 5.1 supports multimodal inputs, whereas Kimi K2 Base does not.

Claude Mythos 5.1 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Claude Mythos 5.1

Text
Images
Audio
Video

Kimi K2 Base

Text
Images
Audio
Video

License

Usage and distribution terms

Claude Mythos 5.1 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 Mythos 5.1

Proprietary

Closed source

Kimi K2 Base

MIT

Open weights

Release Timeline

When each model was launched

Claude Mythos 5.1 was released on 2026-09-01, while Kimi K2 Base was released on 2025-07-11.

Claude Mythos 5.1 is 14 months newer than Kimi K2 Base.

Claude Mythos 5.1

Sep 1, 2026

1 weeks ago

1.1yr newer
Kimi K2 Base

Jul 11, 2025

1.2 years ago

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Claude Mythos 5.1 and Kimi K2 Base side-by-side, then vote on the output you prefer.

Claude Mythos 5.1
✓ Preferred
Kimi K2 Base
Open in Playground

FAQ

Common questions about Claude Mythos 5.1 vs Kimi K2 Base.

Which is better, Claude Mythos 5.1 or Kimi K2 Base?

Claude Mythos 5.1 leads the LLM Stats Score 45.1 to 13.6. Claude Mythos 5.1 is made by Anthropic and Kimi K2 Base 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 Mythos 5.1 compare to Kimi K2 Base in benchmarks?

Claude Mythos 5.1 scores Terminal-Bench 4.0: 60.9%. 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 Mythos 5.1 and Kimi K2 Base?

Claude Mythos 5.1 supports 1.0M 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 Mythos 5.1 and Kimi K2 Base?

Key differences include LLM Stats Score (45.1 vs 13.6), multimodal support (yes vs no), licensing (Proprietary vs MIT). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Mythos 5.1 and Kimi K2 Base?

Claude Mythos 5.1 is developed by Anthropic and Kimi K2 Base is developed by Moonshot AI.

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