Model Comparison

Grok 4.5 vs Llama 3.1 Nemotron Ultra 253B v1Which is better in 2026?

Grok 4.5 significantly outperforms across most benchmarks.

Verdict: Grok 4.5 vs Llama 3.1 Nemotron Ultra 253B v1 — which is better?

Grok 4.5 (by xAI) and Llama 3.1 Nemotron Ultra 253B v1 (by NVIDIA) 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.

Grok 4.5 outperforms in 1 benchmarks (GPQA), while Llama 3.1 Nemotron Ultra 253B v1 is better at 0 benchmarks. Grok 4.5 significantly outperforms across most benchmarks.

Choose Grok 4.5 if…

  • you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
  • you want the most recent training data — it shipped Jul 2026

Choose Llama 3.1 Nemotron Ultra 253B v1 if…

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

Performance Benchmarks

Comparative analysis across standard metrics

1 benchmarks

Grok 4.5 outperforms in 1 benchmarks (GPQA), while Llama 3.1 Nemotron Ultra 253B v1 is better at 0 benchmarks.

Grok 4.5 significantly outperforms across most benchmarks.

Tue Jul 21 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only Grok 4.5 specifies input context (500,000 tokens).

xAI
Grok 4.5
Input500,000 tokens
Output- tokens
NVIDIA
Llama 3.1 Nemotron Ultra 253B v1
Input- tokens
Output- tokens
Tue Jul 21 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Grok 4.5 supports multimodal inputs, whereas Llama 3.1 Nemotron Ultra 253B v1 does not.

Grok 4.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Grok 4.5

Text
Images
Audio
Video

Llama 3.1 Nemotron Ultra 253B v1

Text
Images
Audio
Video

License

Usage and distribution terms

Grok 4.5 is licensed under a proprietary license, while Llama 3.1 Nemotron Ultra 253B v1 uses Llama 3.1 Community License.

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

Grok 4.5

Proprietary

Closed source

Llama 3.1 Nemotron Ultra 253B v1

Llama 3.1 Community License

Open weights

Release Timeline

When each model was launched

Grok 4.5 was released on 2026-07-16, while Llama 3.1 Nemotron Ultra 253B v1 was released on 2025-04-07.

Grok 4.5 is 16 months newer than Llama 3.1 Nemotron Ultra 253B v1.

Grok 4.5

Jul 16, 2026

5 days ago

1.3yr newer
Llama 3.1 Nemotron Ultra 253B v1

Apr 7, 2025

1.3 years ago

Knowledge Cutoff

When training data ends

Grok 4.5 has a knowledge cutoff of 2026-02-01, while Llama 3.1 Nemotron Ultra 253B v1 has a cutoff of 2023-12-01.

Grok 4.5 has more recent training data (up to 2026-02-01), making it potentially better informed about events through that date compared to Llama 3.1 Nemotron Ultra 253B v1 (2023-12-01).

Grok 4.5

Feb 2026

2.2 yr newer
Llama 3.1 Nemotron Ultra 253B v1

Dec 2023

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

xAI
Larger context window (500,000 tokens)
Supports multimodal inputs
Higher GPQA score (93.0% vs 76.0%)
NVIDIA
Has open weights

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Grok 4.5 and Llama 3.1 Nemotron Ultra 253B v1 side-by-side, then vote on the output you prefer.

Grok 4.5
✓ Preferred
Llama 3.1 Nemotron Ultra 253B v1
Open in Playground
AI Model Comparison Table
Feature
xAI
Grok 4.5
NVIDIA
Llama 3.1 Nemotron Ultra 253B v1

FAQ

Common questions about Grok 4.5 vs Llama 3.1 Nemotron Ultra 253B v1.

Which is better, Grok 4.5 or Llama 3.1 Nemotron Ultra 253B v1?

Grok 4.5 significantly outperforms across most benchmarks. Grok 4.5 is made by xAI and Llama 3.1 Nemotron Ultra 253B v1 is made by NVIDIA. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Grok 4.5 compare to Llama 3.1 Nemotron Ultra 253B v1 in benchmarks?

Grok 4.5 scores GPQA: 93.0%, Terminal-Bench 2.1: 83.3%, Artificial Analysis Coding Agent Index v1.1: 76.0%, SWE-Bench Pro: 64.7%, AA-Omniscience Index: 63.0%. Llama 3.1 Nemotron Ultra 253B v1 scores MATH-500: 97.0%, IFEval: 89.5%, GPQA: 76.0%, BFCL v2: 74.1%, AIME 2025: 72.5%.

What are the context window sizes for Grok 4.5 and Llama 3.1 Nemotron Ultra 253B v1?

Grok 4.5 supports 500K tokens and Llama 3.1 Nemotron Ultra 253B v1 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 Grok 4.5 and Llama 3.1 Nemotron Ultra 253B v1?

Key differences include multimodal support (yes vs no), licensing (Proprietary vs Llama 3.1 Community License). See the full comparison above for benchmark-by-benchmark results.

Who makes Grok 4.5 and Llama 3.1 Nemotron Ultra 253B v1?

Grok 4.5 is developed by xAI and Llama 3.1 Nemotron Ultra 253B v1 is developed by NVIDIA.

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