Model Comparison

Nemotron 3 Ultra (550B A55B) vs GPT-5.6 LunaWhich is better in 2026?

GPT-5.6 Luna significantly outperforms across most benchmarks.

Verdict: Nemotron 3 Ultra (550B A55B) vs GPT-5.6 Luna — which is better?

Nemotron 3 Ultra (550B A55B) (by NVIDIA) and GPT-5.6 Luna (by OpenAI) 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.

Nemotron 3 Ultra (550B A55B) outperforms in 0 benchmarks, while GPT-5.6 Luna is better at 4 benchmarks (BrowseComp, GDPval-AA, GPQA, Terminal-Bench 2.1). GPT-5.6 Luna significantly outperforms across most benchmarks.

Choose Nemotron 3 Ultra (550B A55B) if…

  • you need open weights you can self-host or fine-tune

Choose GPT-5.6 Luna if…

  • you want the strongest raw capability — it leads on 4 of 4 shared benchmarks
  • you want the most recent training data — it shipped Jul 2026

Performance Benchmarks

Comparative analysis across standard metrics

4 benchmarks

Nemotron 3 Ultra (550B A55B) outperforms in 0 benchmarks, while GPT-5.6 Luna is better at 4 benchmarks (BrowseComp, GDPval-AA, GPQA, Terminal-Bench 2.1).

GPT-5.6 Luna significantly outperforms across most benchmarks.

Fri Jul 17 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only GPT-5.6 Luna specifies input context (1,050,000 tokens). Only GPT-5.6 Luna specifies output context (128,000 tokens).

NVIDIA
Nemotron 3 Ultra (550B A55B)
Input- tokens
Output- tokens
OpenAI
GPT-5.6 Luna
Input1,050,000 tokens
Output128,000 tokens
Fri Jul 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

GPT-5.6 Luna supports multimodal inputs, whereas Nemotron 3 Ultra (550B A55B) does not.

GPT-5.6 Luna can handle both text and other forms of data like images, making it suitable for multimodal applications.

Nemotron 3 Ultra (550B A55B)

Text
Images
Audio
Video

GPT-5.6 Luna

Text
Images
Audio
Video

License

Usage and distribution terms

Nemotron 3 Ultra (550B A55B) is licensed under OpenMDW License v1.1, while GPT-5.6 Luna uses a proprietary license.

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

Nemotron 3 Ultra (550B A55B)

OpenMDW License v1.1

Open weights

GPT-5.6 Luna

Proprietary

Closed source

Release Timeline

When each model was launched

Nemotron 3 Ultra (550B A55B) was released on 2026-06-04, while GPT-5.6 Luna was released on 2026-07-09.

GPT-5.6 Luna is 1 month newer than Nemotron 3 Ultra (550B A55B).

Nemotron 3 Ultra (550B A55B)

Jun 4, 2026

1 months ago

GPT-5.6 Luna

Jul 9, 2026

1 weeks ago

1mo newer

Knowledge Cutoff

When training data ends

Nemotron 3 Ultra (550B A55B) has a knowledge cutoff of 2025-09-30, while GPT-5.6 Luna has a cutoff of 2026-02-16.

GPT-5.6 Luna has more recent training data (up to 2026-02-16), making it potentially better informed about events through that date compared to Nemotron 3 Ultra (550B A55B) (2025-09-30).

Nemotron 3 Ultra (550B A55B)

Sep 2025

GPT-5.6 Luna

Feb 2026

5 mo newer

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

NVIDIA
Has open weights
OpenAI
Larger context window (1,050,000 tokens)
Supports multimodal inputs
Higher BrowseComp score (83.3% vs 44.4%)
Higher GDPval-AA score (53.1% vs 39.4%)
Higher GPQA score (92.3% vs 87.0%)
Higher Terminal-Bench 2.1 score (84.7% vs 56.4%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Nemotron 3 Ultra (550B A55B) and GPT-5.6 Luna side-by-side, then vote on the output you prefer.

Nemotron 3 Ultra (550B A55B)
✓ Preferred
GPT-5.6 Luna
Open in Playground
AI Model Comparison Table
Feature
NVIDIA
Nemotron 3 Ultra (550B A55B)
OpenAI
GPT-5.6 Luna

FAQ

Common questions about Nemotron 3 Ultra (550B A55B) vs GPT-5.6 Luna.

Which is better, Nemotron 3 Ultra (550B A55B) or GPT-5.6 Luna?

GPT-5.6 Luna significantly outperforms across most benchmarks. Nemotron 3 Ultra (550B A55B) is made by NVIDIA and GPT-5.6 Luna is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Nemotron 3 Ultra (550B A55B) compare to GPT-5.6 Luna in benchmarks?

Nemotron 3 Ultra (550B A55B) scores RULER: 94.7%, IMO-AnswerBench: 92.3%, PinchBench: 90.0%, LiveCodeBench v6: 89.0%, GPQA: 87.0%. GPT-5.6 Luna scores Connectors: 99.9%, HealthBench Consensus: 95.1%, GPQA: 92.3%, Search and Function-Calling: 89.7%, Capture-the-Flag Challenges (Internal): 85.2%.

What are the context window sizes for Nemotron 3 Ultra (550B A55B) and GPT-5.6 Luna?

Nemotron 3 Ultra (550B A55B) supports an unknown number of tokens and GPT-5.6 Luna supports 1.1M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Nemotron 3 Ultra (550B A55B) and GPT-5.6 Luna?

Key differences include multimodal support (no vs yes), licensing (OpenMDW License v1.1 vs Proprietary). See the full comparison above for benchmark-by-benchmark results.

Who makes Nemotron 3 Ultra (550B A55B) and GPT-5.6 Luna?

Nemotron 3 Ultra (550B A55B) is developed by NVIDIA and GPT-5.6 Luna is developed by OpenAI.

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