Llama 3.1 8BvsLlama 3.1 405B
Meta AI vs Meta AI — Side-by-side model comparison
Head-to-Head Comparison
| Metric | Llama 3.1 8B | Llama 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
Llama 3.1 405B ranks higher in arena benchmarks (#9) indicating stronger overall performance.
Llama 3.1 8B has 8B parameters vs Llama 3.1 405B's 405B, which affects inference speed and capability.
When to use Llama 3.1 8B
- +Your use case involves edge deployment, mobile, fast inference
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
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