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

GPT-5.6 Luna leads the LLM Stats Score 45.3 to 36.2. GPT-5.6 Luna is 2.1x cheaper per token.

OpenAI · NVIDIA · Updated for 2026

Which is better?

GPT-5.6 Luna leads the overall LLM Stats Score 45.3 to 36.2, ranking #34 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.

On price, GPT-5.6 Luna is roughly 2.1x 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.

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

Choose GPT-5.6 Luna

  • overall performance matters — it scores 45.3 and ranks #34 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
  • cost matters — it's about 2.1x 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 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
45.3
#34
36.2
#82
Reasoning
43.9
#39
35.4
#85
Coding
36.8
#20
21.0
#97
Agents
31.9
#30
12.4
#105
Cost, coverage & limits
Benchmark wins
3 of 3
0 of 3
Input price
$0.20 / M
$0.50 / M
Output price
$1.20 / M
$2.20 / M
Context window
1,050,000
262,144

Capability indexes

Additional strengths measured across groups of related public benchmarks

4 shared
Index
GPT-5.6 Luna
Nemotron 3 Ultra (550B A55B)
Math
28.8#90
36.4#39
Tool use
22.8#40
0.5#178
Long context
21.2#24
23.3#20
Finance
-1.5#204
29.0#31
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.

Tue Sep 22 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

GPT-5.6 Luna costs less

For input processing, GPT-5.6 Luna ($0.20/1M tokens) is 2.5x cheaper than Nemotron 3 Ultra (550B A55B) ($0.50/1M tokens).

For output processing, GPT-5.6 Luna ($1.20/1M tokens) is 1.8x cheaper than Nemotron 3 Ultra (550B A55B) ($2.20/1M tokens).

In conclusion, Nemotron 3 Ultra (550B A55B) is more expensive than GPT-5.6 Luna.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Tue Sep 22 2026 • llm-stats.com
OpenAI
GPT-5.6 Luna
Input tokens$0.20
Output tokens$1.20
Best providerOpenAI
NVIDIA
Nemotron 3 Ultra (550B A55B)
Input tokens$0.50
Output tokens$2.20
Best providerDeepinfra
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

GPT-5.6 Luna accepts 1,050,000 input tokens compared to Nemotron 3 Ultra (550B A55B)'s 262,144 tokens. Nemotron 3 Ultra (550B A55B) can generate longer responses up to 262,144 tokens, while GPT-5.6 Luna is limited to 128,000 tokens.

OpenAI
GPT-5.6 Luna
Input1,050,000 tokens
Output128,000 tokens
NVIDIA
Nemotron 3 Ultra (550B A55B)
Input262,144 tokens
Output262,144 tokens
Tue Sep 22 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

2 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

Provider Availability

GPT-5.6 Luna is available from OpenAI. Nemotron 3 Ultra (550B A55B) is available from DeepInfra.

GPT-5.6 Luna

openai logo
OpenAI
Input Price:Input: $0.20/1MOutput Price:Output: $1.20/1M

Nemotron 3 Ultra (550B A55B)

deepinfra logo
Deepinfra
Input Price:Input: $0.50/1MOutput Price:Output: $2.20/1M
* Prices shown are per million tokens

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 45.3 to 36.2. 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%.

Is GPT-5.6 Luna cheaper than Nemotron 3 Ultra (550B A55B)?

GPT-5.6 Luna is 2.5x cheaper for input tokens. GPT-5.6 Luna costs $0.20/M input and $1.20/M output via openai. Nemotron 3 Ultra (550B A55B) costs $0.50/M input and $2.20/M output via deepinfra.

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 262K 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 (45.3 vs 36.2), context window (1.1M vs 262K), input pricing ($0.20 vs $0.50/M), 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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