Model Comparison
GPT-5.6 Luna vs Kimi K2 0905Which is better in 2026?
GPT-5.6 Luna significantly outperforms across most benchmarks. GPT-5.6 Luna is 2.4x cheaper per token.
Verdict: GPT-5.6 Luna vs Kimi K2 0905 — which is better?
GPT-5.6 Luna (by OpenAI) and Kimi K2 0905 (by Moonshot AI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
GPT-5.6 Luna outperforms in 1 benchmarks (GPQA), while Kimi K2 0905 is better at 0 benchmarks. GPT-5.6 Luna significantly outperforms across most benchmarks.
On price, GPT-5.6 Luna is roughly 2.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-5.6 Luna also accepts a larger context window (1,050,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose GPT-5.6 Luna if…
- you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
- cost matters — it's about 2.4x cheaper per token
- you process long inputs — it offers a 1,050,000 token context window
- you want the most recent training data — it shipped Jul 2026
Choose Kimi K2 0905 if…
- you want predictable pricing at $0.60/M input and $2.50/M output
Performance Benchmarks
Comparative analysis across standard metrics
GPT-5.6 Luna outperforms in 1 benchmarks (GPQA), while Kimi K2 0905 is better at 0 benchmarks.
GPT-5.6 Luna significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.6 Luna ($0.20/1M tokens) is 3.0x cheaper than Kimi K2 0905 ($0.60/1M tokens).
For output processing, GPT-5.6 Luna ($1.20/1M tokens) is 2.1x cheaper than Kimi K2 0905 ($2.50/1M tokens).
In conclusion, Kimi K2 0905 is more expensive than GPT-5.6 Luna.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT-5.6 Luna accepts 1,050,000 input tokens compared to Kimi K2 0905's 262,144 tokens. Kimi K2 0905 can generate longer responses up to 262,144 tokens, while GPT-5.6 Luna is limited to 128,000 tokens.
Input Capabilities
Supported data types and modalities
GPT-5.6 Luna supports multimodal inputs, whereas Kimi K2 0905 does not.
GPT-5.6 Luna can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT-5.6 Luna
Kimi K2 0905
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-5.6 Luna was released on 2026-07-09, while Kimi K2 0905 was released on 2025-09-05.
GPT-5.6 Luna is 10 months newer than Kimi K2 0905.
Jul 9, 2026
4 weeks ago
10mo newerSep 5, 2025
11 months ago
Knowledge Cutoff
When training data ends
GPT-5.6 Luna has a documented knowledge cutoff of 2026-02-16, while Kimi K2 0905's cutoff date is not specified.
We can confirm GPT-5.6 Luna's training data extends to 2026-02-16, but cannot make a direct comparison without Kimi K2 0905's cutoff date.
Feb 2026
—
Provider Availability
GPT-5.6 Luna is available from OpenAI. Kimi K2 0905 is available from Novita.
GPT-5.6 Luna
Kimi K2 0905
Outputs Comparison
Key Takeaways
GPT-5.6 Luna
View detailsOpenAI
Kimi K2 0905
View detailsMoonshot AI
No standout differentiators in the data we have for this pair.
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against GPT-5.6 Luna and Kimi K2 0905 side-by-side, then vote on the output you prefer.
| Feature | | |
|---|
FAQ
Common questions about GPT-5.6 Luna vs Kimi K2 0905.