Claude Sonnet 4.5 vs Kimi K2.5
Claude Sonnet 4.5 and Kimi K2.5 are closely matched at 32.4 and 39.1 on the LLM Stats Score. Kimi K2.5 is 5.0x cheaper per token.
Anthropic · Moonshot AI · Updated for 2026
Which is better?
Claude Sonnet 4.5 and Kimi K2.5 are closely matched on the overall LLM Stats Score at 32.4 and 39.1.
In the 2 individual benchmarks reported for both models, Kimi K2.5 wins 2; this is a narrower head-to-head signal than the composite indexes.
On price, Kimi K2.5 is roughly 5.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Kimi K2.5 also accepts a larger context window (262,100 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 4.5
- you want predictable pricing at $3.00/M input and $15.00/M output
Choose Kimi K2.5
- you value its reported benchmark strengths — it wins 2 of 2 exact shared results
- cost matters — it's about 5.0x cheaper per token
- you process long inputs — it offers a 262,100 token context window
- you want the most recent training data — it shipped Jan 2026
- 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
9 reported for Claude Sonnet 4.5 · 40 for Kimi K2.5
Claude Sonnet 4.5 outperforms in 0 benchmarks, while Kimi K2.5 is better at 2 benchmarks (AIME 2025, GPQA).
Kimi K2.5 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 4.5 ($3.00/1M tokens) is 5.0x more expensive than Kimi K2.5 ($0.60/1M tokens).
For output processing, Claude Sonnet 4.5 ($15.00/1M tokens) is 5.0x more expensive than Kimi K2.5 ($3.00/1M tokens).
In conclusion, Claude Sonnet 4.5 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
Kimi K2.5 accepts 262,100 input tokens compared to Claude Sonnet 4.5's 200,000 tokens. Kimi K2.5 can generate longer responses up to 262,100 tokens, while Claude Sonnet 4.5 is limited to 64,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Sonnet 4.5 and Kimi K2.5 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Sonnet 4.5
Kimi K2.5
License
Usage and distribution terms
Claude Sonnet 4.5 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 Sonnet 4.5 was released on 2025-09-29, while Kimi K2.5 was released on 2026-01-27.
Kimi K2.5 is 4 months newer than Claude Sonnet 4.5.
Sep 29, 2025
11 months ago
Jan 27, 2026
7 months ago
4mo newerKnowledge Cutoff
When training data ends
Claude Sonnet 4.5 has a documented knowledge cutoff of 2025-01-31, while Kimi K2.5's cutoff date is not specified.
We can confirm Claude Sonnet 4.5's training data extends to 2025-01-31, but cannot make a direct comparison without Kimi K2.5's cutoff date.
Jan 2025
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Provider Availability
Claude Sonnet 4.5 is available from Anthropic. Kimi K2.5 is available from Fireworks, Moonshot AI.
Claude Sonnet 4.5
Kimi K2.5
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Sonnet 4.5 and Kimi K2.5 side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Sonnet 4.5 vs Kimi K2.5.