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Llama 3.1 8BvsLlama 3.1 405B

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 8BLlama 3.1 405B
Provider
Meta AI
Meta AI
Arena Rank
#22
#9
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
8B
405B
Open Source
Yes
Yes
Best For
Edge deployment, mobile, fast inference
Complex reasoning, coding, multilingual tasks
Release Date
Jul 23, 2024
Jul 23, 2024

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.

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.

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

1

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

2

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

L

When to use Llama 3.1 8B

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

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 8B or Llama 3.1 405B?
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 8B pricing compare to Llama 3.1 405B?
Llama 3.1 8B charges Free (open) per 1M input tokens and Free (open) per 1M output tokens. Llama 3.1 405B 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 8B and Llama 3.1 405B?
Llama 3.1 8B supports a 128K token context window, while Llama 3.1 405B supports 128K tokens. Context window size matters most for tasks involving long documents, large codebases, or extended conversations.
Can I use Llama 3.1 8B or Llama 3.1 405B for free?
Llama 3.1 8B is a paid API model starting at Free (open) per 1M input tokens. Llama 3.1 405B 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 8B or Llama 3.1 405B?
Llama 3.1 8B holds arena rank #22, while Llama 3.1 405B holds rank #9. 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 8B or Llama 3.1 405B better for coding?
Llama 3.1 8B's primary strength is edge deployment, mobile, fast inference. Llama 3.1 405B is specifically optimized for coding tasks. For coding specifically, arena rank and code-specific benchmarks are the best indicators of performance.