Model Comparison
Grok-2 vs Llama 3.1 405B InstructWhich is better in 2026?
Grok-2 significantly outperforms across most benchmarks. Llama 3.1 405B Instruct is 4.5x cheaper per token.
Verdict: Grok-2 vs Llama 3.1 405B Instruct — which is better?
Grok-2 (by xAI) and Llama 3.1 405B Instruct (by Meta) 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-2 outperforms in 4 benchmarks (GPQA, MATH, MMLU, MMLU-Pro), while Llama 3.1 405B Instruct is better at 1 benchmark (HumanEval). Grok-2 significantly outperforms across most benchmarks.
On price, Llama 3.1 405B Instruct is roughly 4.5x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Choose Grok-2 if…
- you want the strongest raw capability — it leads on 4 of 5 shared benchmarks
- you want the most recent training data — it shipped Aug 2024
Choose Llama 3.1 405B Instruct if…
- cost matters — it's about 4.5x cheaper per token
- you need open weights you can self-host or fine-tune
Performance Benchmarks
Comparative analysis across standard metrics
Grok-2 outperforms in 4 benchmarks (GPQA, MATH, MMLU, MMLU-Pro), while Llama 3.1 405B Instruct is better at 1 benchmark (HumanEval).
Grok-2 significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, Grok-2 ($2.00/1M tokens) is 2.2x more expensive than Llama 3.1 405B Instruct ($0.89/1M tokens).
For output processing, Grok-2 ($10.00/1M tokens) is 11.2x more expensive than Llama 3.1 405B Instruct ($0.89/1M tokens).
In conclusion, Grok-2 is more expensive than Llama 3.1 405B Instruct.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Both models have the same input context window of 128,000 tokens. Llama 3.1 405B Instruct can generate longer responses up to 128,000 tokens, while Grok-2 is limited to 8,000 tokens.
Input Capabilities
Supported data types and modalities
Grok-2 supports multimodal inputs, whereas Llama 3.1 405B Instruct does not.
Grok-2 can handle both text and other forms of data like images, making it suitable for multimodal applications.
Grok-2
Llama 3.1 405B Instruct
License
Usage and distribution terms
Grok-2 is licensed under a proprietary license, while Llama 3.1 405B Instruct uses Llama 3.1 Community License.
License differences may affect how you can use these models in commercial or open-source projects.
Proprietary
Closed source
Llama 3.1 Community License
Open weights
Release Timeline
When each model was launched
Grok-2 was released on 2024-08-13, while Llama 3.1 405B Instruct was released on 2024-07-23.
Grok-2 is 1 month newer than Llama 3.1 405B Instruct.
Aug 13, 2024
1.9 years ago
3w newerJul 23, 2024
2.0 years ago
Knowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
Grok-2 is available from xAI. Llama 3.1 405B Instruct is available from Lambda, DeepInfra, Fireworks, Bedrock, Together, Hyperbolic, Google, Replicate.
Grok-2
Llama 3.1 405B Instruct
Outputs Comparison
Key Takeaways
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against Grok-2 and Llama 3.1 405B Instruct side-by-side, then vote on the output you prefer.
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FAQ
Common questions about Grok-2 vs Llama 3.1 405B Instruct.