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Llama 3.1 405BvsLlama 3.1 8B

Meta AI vs Meta AI — Side-by-side model comparison

Llama 3.1 405B leads 2/5 categories

Head-to-Head Comparison

MetricLlama 3.1 405BLlama 3.1 8B
Provider
Meta AI
Meta AI
Arena Rank
#9
#22
Context Window
128K
128K
Input Pricing
Free (open)/1M tokens
Free (open)/1M tokens
Output Pricing
Free (open)/1M tokens
Free (open)/1M tokens
Parameters
405B
8B
Open Source
Yes
Yes
Best For
Complex reasoning, coding, multilingual tasks
Edge deployment, mobile, fast inference
Release Date
Jul 23, 2024
Jul 23, 2024

Llama 3.1 405B

Llama 3.1 405B, developed by Meta AI, is the largest open-source language model with 405 billion parameters and a 128K token context window. The model rivaled GPT-4-class performance on many benchmarks at the time of its release, representing one of the most ambitious open-source AI projects in history. Training required massive computational resources, but Meta open-sourced all weights, enabling the global research community to study, fine-tune, and deploy it freely. Llama 3.1 405B requires multiple high-end GPUs for inference, limiting deployment to organizations with substantial compute infrastructure. It supports multilingual tasks, advanced reasoning, and tool use. Llama 3.1 405B ranks #9 on the Chatbot Arena leaderboard, confirming that open-source models can compete at the frontier of AI capability when sufficient resources are invested in training.

Llama 3.1 8B

Llama 3.1 8B, developed by Meta AI, is a compact open-source model with 8 billion parameters and a 128K token context window, a substantial upgrade from the 8K context of Llama 3. The model handles edge deployment, mobile AI, and fast inference tasks while supporting significantly longer document processing. Its extended context window enables use cases like document summarization, long-form analysis, and RAG applications that were impractical with the shorter-context predecessor. Llama 3.1 8B can run on consumer GPUs and mobile device accelerators, making it one of the most deployable long-context models available. Free and open-source under Meta's license, it supports commercial use and fine-tuning. Llama 3.1 8B ranks #22 on the Chatbot Arena leaderboard, demonstrating competitive performance for its compact parameter count.

Key Differences: Llama 3.1 405B vs Llama 3.1 8B

1

Llama 3.1 405B ranks higher in arena benchmarks (#9) indicating stronger overall performance.

2

Llama 3.1 405B has 405B parameters vs Llama 3.1 8B's 8B, which affects inference speed and capability.

L

When to use Llama 3.1 405B

  • +You need the highest quality output based on arena rankings
  • +Your use case involves complex reasoning, coding, multilingual tasks
View full Llama 3.1 405B specs →
L

When to use Llama 3.1 8B

  • +Your use case involves edge deployment, mobile, fast inference
View full Llama 3.1 8B specs →

The Verdict

Llama 3.1 405B wins our head-to-head comparison with 2 out of 5 category wins. It's the stronger choice for complex reasoning, coding, multilingual tasks, though Llama 3.1 8B holds an edge in edge deployment, mobile, fast inference.

Last compared: April 2026 · Data sourced from public benchmarks and official pricing pages

Frequently Asked Questions

Which is better, Llama 3.1 405B or Llama 3.1 8B?
In our head-to-head comparison, Llama 3.1 405B leads in 2 out of 5 categories (arena rank, context window, input pricing, output pricing, and parameters). Llama 3.1 405B excels at complex reasoning, coding, multilingual tasks, while Llama 3.1 8B is better suited for edge deployment, mobile, fast inference. The best choice depends on your specific requirements, budget, and use case.
How does Llama 3.1 405B pricing compare to Llama 3.1 8B?
Llama 3.1 405B charges Free (open) per 1M input tokens and Free (open) per 1M output tokens. Llama 3.1 8B charges Free (open) per 1M input tokens and Free (open) per 1M output tokens. For high-volume production workloads, the pricing difference can significantly impact total cost of ownership.
What is the context window difference between Llama 3.1 405B and Llama 3.1 8B?
Llama 3.1 405B supports a 128K token context window, while Llama 3.1 8B supports 128K tokens. Context window size matters most for tasks involving long documents, large codebases, or extended conversations.
Can I use Llama 3.1 405B or Llama 3.1 8B for free?
Llama 3.1 405B is a paid API model starting at Free (open) per 1M input tokens. Llama 3.1 8B is a paid API model starting at Free (open) per 1M input tokens. Open-source models can be self-hosted for free but require your own GPU infrastructure.
Which model has better benchmarks, Llama 3.1 405B or Llama 3.1 8B?
Llama 3.1 405B holds arena rank #9, while Llama 3.1 8B holds rank #22. Llama 3.1 405B performs better in overall arena benchmarks, which aggregate human preference ratings across coding, reasoning, and general tasks. Note that benchmarks don't capture every use case — we recommend testing both models on your specific tasks.
Is Llama 3.1 405B or Llama 3.1 8B better for coding?
Llama 3.1 405B is specifically optimized for coding tasks. Llama 3.1 8B's primary strength is edge deployment, mobile, fast inference. For coding specifically, arena rank and code-specific benchmarks are the best indicators of performance.