Claude Sonnet 5.5 vs Kimi K3
Claude Sonnet 5.5 leads the LLM Stats Score 58.0 to 52.4. Claude Sonnet 5.5 is 1.4x cheaper per token.
Anthropic · Moonshot AI · Updated for 2026
Which is better?
Claude Sonnet 5.5 leads the overall LLM Stats Score 58.0 to 52.4, ranking #3 overall.
In the 4 individual benchmarks reported for both models, Claude Sonnet 5.5 wins 4; this is a narrower head-to-head signal than the composite indexes.
On price, Claude Sonnet 5.5 is roughly 1.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Kimi K3 also accepts a larger context window (1,048,576 input tokens), making it the stronger choice for long documents and large codebases.
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 4 of 4 exact shared results
- cost matters — it's about 1.4x cheaper per token
- you want the most recent training data — it shipped Sep 2026
Choose Kimi K3
- you process long inputs — it offers a 1,048,576 token context window
- you need open weights you can self-host or fine-tune
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
47 reported for Claude Sonnet 5.5 · 31 for Kimi K3
Claude Sonnet 5.5 outperforms in 4 benchmarks (AutomationBench, DeepSWE 1.1, OfficeQA Pro, Program Bench), while Kimi K3 is better at 0 benchmarks.
Claude Sonnet 5.5 significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Sonnet 5.5 ($2.00/1M tokens) is 1.4x cheaper than Kimi K3 ($2.85/1M tokens).
For output processing, Claude Sonnet 5.5 ($10.00/1M tokens) is 1.4x cheaper than Kimi K3 ($14.25/1M tokens).
In conclusion, Kimi K3 is more expensive than Claude Sonnet 5.5.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Kimi K3 accepts 1,048,576 input tokens compared to Claude Sonnet 5.5's 1,000,000 tokens. Kimi K3 can generate longer responses up to 1,048,576 tokens, while Claude Sonnet 5.5 is limited to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Sonnet 5.5 and Kimi K3 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Sonnet 5.5
Kimi K3
License
Usage and distribution terms
Claude Sonnet 5.5 is licensed under a proprietary license, while Kimi K3 uses Kimi K3 License.
License differences may affect how you can use these models in commercial or open-source projects.
Proprietary
Closed source
Kimi K3 License
Open weights
Release Timeline
When each model was launched
Claude Sonnet 5.5 was released on 2026-09-28, while Kimi K3 was released on 2026-07-16.
Claude Sonnet 5.5 is 2 months newer than Kimi K3.
Sep 28, 2026
1 days ago
2mo newerJul 16, 2026
2 months ago
Knowledge Cutoff
When training data ends
Claude Sonnet 5.5 has a documented knowledge cutoff of 2026-06-01, while Kimi K3'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 K3's cutoff date.
Jun 2026
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Provider Availability
Claude Sonnet 5.5 is available from Anthropic. Kimi K3 is available from DeepInfra, Fireworks, Moonshot AI, Novita, Together.
Claude Sonnet 5.5
Kimi K3
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Sonnet 5.5 and Kimi K3 side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Sonnet 5.5 vs Kimi K3.