GPT-5.5 Pro vs Kimi K2.8 Preview
Comparing GPT-5.5 Pro and Kimi K2.8 Preview across benchmarks, pricing, and capabilities.
OpenAI · Moonshot AI · Updated for 2026
Which is better?
GPT-5.5 Pro and Kimi K2.8 Preview trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.
GPT-5.5 Pro also accepts a larger context window (1,050,000 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 GPT-5.5 Pro
- you process long inputs — it offers a 1,050,000 token context window
Choose Kimi K2.8 Preview
- you want the most recent training data — it shipped Sep 2026
At a glance
The differences that matter most.
Individual benchmarks
5 reported for GPT-5.5 Pro · 0 for Kimi K2.8 Preview
GPT-5.5 Pro and Kimi K2.8 Previewdon'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
GPT-5.5 Pro accepts 1,050,000 input tokens compared to Kimi K2.8 Preview's 1,048,576 tokens. Only GPT-5.5 Pro specifies output context (128,000 tokens).
Input capabilities
Documented input modalities across available providers
Both GPT-5.5 Pro and Kimi K2.8 Preview support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.5 Pro
Kimi K2.8 Preview
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
GPT-5.5 Pro was released on 2026-04-23, while Kimi K2.8 Preview was released on 2026-09-11.
Kimi K2.8 Preview is 5 months newer than GPT-5.5 Pro.
Apr 23, 2026
5 months ago
Sep 11, 2026
1 weeks ago
4mo newerKnowledge Cutoff
When training data ends
GPT-5.5 Pro has a documented knowledge cutoff of 2025-12-01, while Kimi K2.8 Preview's cutoff date is not specified.
We can confirm GPT-5.5 Pro's training data extends to 2025-12-01, but cannot make a direct comparison without Kimi K2.8 Preview's cutoff date.
Dec 2025
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Provider Availability
GPT-5.5 Pro is available from OpenAI. Kimi K2.8 Preview is available from Moonshot AI.
GPT-5.5 Pro
Kimi K2.8 Preview
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5.5 Pro and Kimi K2.8 Preview side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5.5 Pro vs Kimi K2.8 Preview.