Model Comparison
GPT-5.6 Luna vs Kimi K3Which is better in 2026?
Kimi K3 significantly outperforms across most benchmarks. GPT-5.6 Luna is 2.7x cheaper per token.
Verdict: GPT-5.6 Luna vs Kimi K3 — which is better?
GPT-5.6 Luna (by OpenAI) and Kimi K3 (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 0 benchmarks, while Kimi K3 is better at 9 benchmarks (AutomationBench, BrowseComp, DeepSWE, GDPval-AA, GPQA, MMMU-Pro, MMMU-Pro (with tools), Terminal-Bench 2.1, Toolathlon). Kimi K3 significantly outperforms across most benchmarks.
On price, GPT-5.6 Luna is roughly 2.7x 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…
- cost matters — it's about 2.7x cheaper per token
- you process long inputs — it offers a 1,050,000 token context window
Choose Kimi K3 if…
- you want the strongest raw capability — it leads on 9 of 9 shared benchmarks
- you want the most recent training data — it shipped Jul 2026
Performance Benchmarks
Comparative analysis across standard metrics
GPT-5.6 Luna outperforms in 0 benchmarks, while Kimi K3 is better at 9 benchmarks (AutomationBench, BrowseComp, DeepSWE, GDPval-AA, GPQA, MMMU-Pro, MMMU-Pro (with tools), Terminal-Bench 2.1, Toolathlon).
Kimi K3 significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.6 Luna ($1.00/1M tokens) is 3.0x cheaper than Kimi K3 ($3.00/1M tokens).
For output processing, GPT-5.6 Luna ($6.00/1M tokens) is 2.5x cheaper than Kimi K3 ($15.00/1M tokens).
In conclusion, Kimi K3 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 K3's 1,048,576 tokens. Kimi K3 can generate longer responses up to 1,048,576 tokens, while GPT-5.6 Luna is limited to 128,000 tokens.
Input Capabilities
Supported data types and modalities
Both GPT-5.6 Luna and Kimi K3 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.6 Luna
Kimi K3
Release Timeline
When each model was launched
GPT-5.6 Luna was released on 2026-07-09, while Kimi K3 was released on 2026-07-16.
Kimi K3 is 0 month newer than GPT-5.6 Luna.
Jul 9, 2026
1 weeks ago
Jul 16, 2026
2 days ago
1w newerKnowledge Cutoff
When training data ends
GPT-5.6 Luna has a documented knowledge cutoff of 2026-02-16, while Kimi K3'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 K3's cutoff date.
Feb 2026
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Provider Availability
GPT-5.6 Luna is available from OpenAI. Kimi K3 is available from Moonshot AI.
GPT-5.6 Luna
Kimi K3
Outputs Comparison
Key Takeaways
GPT-5.6 Luna
View detailsOpenAI
Kimi K3
View detailsMoonshot AI
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against GPT-5.6 Luna and Kimi K3 side-by-side, then vote on the output you prefer.
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FAQ
Common questions about GPT-5.6 Luna vs Kimi K3.