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GPT-5.6 Luna vs Nemotron 3 Ultra (550B A55B)

GPT-5.6 Luna leads the LLM Stats Score 45.4 to 36.3.

OpenAI · NVIDIA · Updated for 2026

Which is better?

GPT-5.6 Luna leads the overall LLM Stats Score 45.4 to 36.3, ranking #29 overall.

In the 3 individual benchmarks reported for both models, GPT-5.6 Luna wins 3; this is a narrower head-to-head signal than the composite indexes.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose GPT-5.6 Luna

  • overall performance matters — it scores 45.4 and ranks #29 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you value its reported benchmark strengths — it wins 3 of 3 exact shared results
  • you want the most recent training data — it shipped Jul 2026

Choose Nemotron 3 Ultra (550B A55B)

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

At a glance

The differences that matter most.

GPT-5.6 Luna
OpenAI
Nemotron 3 Ultra (550B A55B)
NVIDIA
Core performance indexes
LLM Stats Score
45.4
#29
36.3
#74
Reasoning
44.4
#33
35.4
#76
Coding
36.5
#19
21.3
#84
Agents
31.3
#25
11.7
#98
Cost, coverage & limits
Benchmark wins
3 of 3
0 of 3
Input price
$0.20 / M
— / M
Output price
$1.20 / M
— / M
Context window
1,050,000
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

4 shared
Index
GPT-5.6 Luna
Nemotron 3 Ultra (550B A55B)
Math
28.7#86
36.2#38
Tool use
25.6#32
3.7#154
Long context
21.3#23
23.2#19
Finance
-1.5#195
28.9#27
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

45 reported for GPT-5.6 Luna · 26 for Nemotron 3 Ultra (550B A55B)

3 shared

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

GPT-5.6 Luna significantly outperforms across most benchmarks.

Sun Sep 06 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

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).

OpenAI
GPT-5.6 Luna
Input1,050,000 tokens
Output128,000 tokens
NVIDIA
Nemotron 3 Ultra (550B A55B)
Input- tokens
Output- tokens
Sun Sep 06 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

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.

GPT-5.6 Luna

Text
Images
Audio
Video

Nemotron 3 Ultra (550B A55B)

Text
Images
Audio
Video

License

Usage and distribution terms

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

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

GPT-5.6 Luna

Proprietary

Closed source

Nemotron 3 Ultra (550B A55B)

OpenMDW License v1.1

Open weights

Release Timeline

When each model was launched

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

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

GPT-5.6 Luna

Jul 9, 2026

1 months ago

1mo newer
Nemotron 3 Ultra (550B A55B)

Jun 4, 2026

3 months ago

Knowledge Cutoff

When training data ends

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

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).

GPT-5.6 Luna

Feb 2026

5 mo newer
Nemotron 3 Ultra (550B A55B)

Sep 2025

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

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

GPT-5.6 Luna
✓ Preferred
Nemotron 3 Ultra (550B A55B)
Open in Playground

FAQ

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

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

GPT-5.6 Luna leads the LLM Stats Score 45.4 to 36.3. GPT-5.6 Luna is made by OpenAI and Nemotron 3 Ultra (550B A55B) is made by NVIDIA. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

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

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%. Nemotron 3 Ultra (550B A55B) scores RULER: 94.7%, IMO-AnswerBench: 92.3%, PinchBench: 90.0%, LiveCodeBench v6: 89.0%, GPQA: 87.0%.

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

GPT-5.6 Luna supports 1.1M tokens and Nemotron 3 Ultra (550B A55B) 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-5.6 Luna and Nemotron 3 Ultra (550B A55B)?

Key differences include LLM Stats Score (45.4 vs 36.3), multimodal support (yes vs no), licensing (Proprietary vs OpenMDW License v1.1). See the full comparison above for benchmark-by-benchmark results.

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

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

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