Claude Opus 5.5 vs Kimi K2.5
Claude Opus 5.5 leads the LLM Stats Score 59.7 to 38.8. Kimi K2.5 is 6.7x cheaper per token.
Anthropic · Moonshot AI · Updated for 2026
Which is better?
Claude Opus 5.5 leads the overall LLM Stats Score 59.7 to 38.8, ranking #1 overall.
In the 2 individual benchmarks reported for both models, Claude Opus 5.5 wins 2; this is a narrower head-to-head signal than the composite indexes.
On price, Kimi K2.5 is roughly 6.7x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Claude Opus 5.5 also accepts a larger context window (1,000,000 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 Opus 5.5
- overall performance matters — it scores 59.7 and ranks #1 on LLM Stats
- your work emphasizes reasoning and coding — it leads those capability indexes
- you value its reported benchmark strengths — it wins 2 of 2 exact shared results
- you process long inputs — it offers a 1,000,000 token context window
- you want the most recent training data — it shipped Sep 2026
Choose Kimi K2.5
- cost matters — it's about 6.7x cheaper per token
- 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
31 reported for Claude Opus 5.5 · 40 for Kimi K2.5
Claude Opus 5.5 outperforms in 2 benchmarks (SWE-bench Multilingual, SWE-Bench Pro), while Kimi K2.5 is better at 0 benchmarks.
Claude Opus 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 Opus 5.5 ($4.00/1M tokens) is 6.7x more expensive than Kimi K2.5 ($0.60/1M tokens).
For output processing, Claude Opus 5.5 ($20.00/1M tokens) is 6.7x more expensive than Kimi K2.5 ($3.00/1M tokens).
In conclusion, Claude Opus 5.5 is more expensive than Kimi K2.5.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Claude Opus 5.5 accepts 1,000,000 input tokens compared to Kimi K2.5's 262,100 tokens. Kimi K2.5 can generate longer responses up to 262,100 tokens, while Claude Opus 5.5 is limited to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Opus 5.5 and Kimi K2.5 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Opus 5.5
Kimi K2.5
License
Usage and distribution terms
Claude Opus 5.5 is licensed under a proprietary license, while Kimi K2.5 uses MIT.
License differences may affect how you can use these models in commercial or open-source projects.
Proprietary
Closed source
MIT
Open weights
Release Timeline
When each model was launched
Claude Opus 5.5 was released on 2026-09-22, while Kimi K2.5 was released on 2026-01-27.
Claude Opus 5.5 is 8 months newer than Kimi K2.5.
Sep 22, 2026
0 days ago
7mo newerJan 27, 2026
7 months ago
Knowledge Cutoff
When training data ends
Claude Opus 5.5 has a documented knowledge cutoff of 2026-06-01, while Kimi K2.5's cutoff date is not specified.
We can confirm Claude Opus 5.5's training data extends to 2026-06-01, but cannot make a direct comparison without Kimi K2.5's cutoff date.
Jun 2026
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Provider Availability
Claude Opus 5.5 is available from Anthropic. Kimi K2.5 is available from Fireworks, Moonshot AI.
Claude Opus 5.5
Kimi K2.5
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Opus 5.5 and Kimi K2.5 side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Opus 5.5 vs Kimi K2.5.