Model Comparison

GPT-5 nano vs Kimi K2-Instruct-0905Which is better in 2026?

GPT-5 nano shows notably better performance in the majority of benchmarks.

Verdict: GPT-5 nano vs Kimi K2-Instruct-0905 — which is better?

GPT-5 nano (by OpenAI) and Kimi K2-Instruct-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 nano outperforms in 3 benchmarks (AIME 2025, HMMT 2025, Humanity's Last Exam), while Kimi K2-Instruct-0905 is better at 1 benchmark (GPQA). GPT-5 nano shows notably better performance in the majority of benchmarks.

Choose GPT-5 nano if…

  • you want the strongest raw capability — it leads on 3 of 4 shared benchmarks

Choose Kimi K2-Instruct-0905 if…

  • you want the most recent training data — it shipped Sep 2025
  • you need open weights you can self-host or fine-tune

Performance Benchmarks

Comparative analysis across standard metrics

4 benchmarks

GPT-5 nano outperforms in 3 benchmarks (AIME 2025, HMMT 2025, Humanity's Last Exam), while Kimi K2-Instruct-0905 is better at 1 benchmark (GPQA).

GPT-5 nano shows notably better performance in the majority of benchmarks.

Sat Jul 18 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only GPT-5 nano specifies input context (400,000 tokens). Only GPT-5 nano specifies output context (128,000 tokens).

OpenAI
GPT-5 nano
Input400,000 tokens
Output128,000 tokens
Moonshot AI
Kimi K2-Instruct-0905
Input- tokens
Output- tokens
Sat Jul 18 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

GPT-5 nano supports multimodal inputs, whereas Kimi K2-Instruct-0905 does not.

GPT-5 nano can handle both text and other forms of data like images, making it suitable for multimodal applications.

GPT-5 nano

Text
Images
Audio
Video

Kimi K2-Instruct-0905

Text
Images
Audio
Video

License

Usage and distribution terms

GPT-5 nano is licensed under a proprietary license, while Kimi K2-Instruct-0905 uses MIT.

License differences may affect how you can use these models in commercial or open-source projects.

GPT-5 nano

Proprietary

Closed source

Kimi K2-Instruct-0905

MIT

Open weights

Release Timeline

When each model was launched

GPT-5 nano was released on 2025-08-07, while Kimi K2-Instruct-0905 was released on 2025-09-05.

Kimi K2-Instruct-0905 is 1 month newer than GPT-5 nano.

GPT-5 nano

Aug 7, 2025

11 months ago

Kimi K2-Instruct-0905

Sep 5, 2025

10 months ago

4w newer

Knowledge Cutoff

When training data ends

GPT-5 nano has a documented knowledge cutoff of 2024-05-30, while Kimi K2-Instruct-0905's cutoff date is not specified.

We can confirm GPT-5 nano's training data extends to 2024-05-30, but cannot make a direct comparison without Kimi K2-Instruct-0905's cutoff date.

GPT-5 nano

May 2024

Kimi K2-Instruct-0905

—

Outputs Comparison

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Key Takeaways

OpenAI
Larger context window (400,000 tokens)
Supports multimodal inputs
Higher AIME 2025 score (85.2% vs 49.5%)
Higher HMMT 2025 score (75.6% vs 38.8%)
Higher Humanity's Last Exam score (8.7% vs 4.7%)
Moonshot AI
Has open weights
Higher GPQA score (75.1% vs 71.2%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against GPT-5 nano and Kimi K2-Instruct-0905 side-by-side, then vote on the output you prefer.

GPT-5 nano
✓ Preferred
Kimi K2-Instruct-0905
Open in Playground
AI Model Comparison Table
Feature
OpenAI
GPT-5 nano
Moonshot AI
Kimi K2-Instruct-0905

FAQ

Common questions about GPT-5 nano vs Kimi K2-Instruct-0905.

Which is better, GPT-5 nano or Kimi K2-Instruct-0905?

GPT-5 nano shows notably better performance in the majority of benchmarks. GPT-5 nano is made by OpenAI and Kimi K2-Instruct-0905 is made by Moonshot AI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does GPT-5 nano compare to Kimi K2-Instruct-0905 in benchmarks?

GPT-5 nano scores AIME 2025: 85.2%, HMMT 2025: 75.6%, GPQA: 71.2%, FrontierMath: 9.6%, Humanity's Last Exam: 8.7%. Kimi K2-Instruct-0905 scores MATH-500: 97.4%, MMLU-Redux: 92.7%, IFEval: 89.8%, AutoLogi: 89.5%, MMLU: 89.5%.

What are the context window sizes for GPT-5 nano and Kimi K2-Instruct-0905?

GPT-5 nano supports 400K tokens and Kimi K2-Instruct-0905 supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT-5 nano and Kimi K2-Instruct-0905?

Key differences include multimodal support (yes vs no), licensing (Proprietary vs MIT). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT-5 nano and Kimi K2-Instruct-0905?

GPT-5 nano is developed by OpenAI and Kimi K2-Instruct-0905 is developed by Moonshot AI.

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