Meta: Llama 3.1 405B (base)
Analysis Summary
Llama 3.1 405B is Meta's largest open-weight model from the Llama 3.1 generation, with an intelligence index of 8.5 and strong MMLU Pro and GPQA scores. As a base model, it lacks tool use, function calling, and vision support, which limits its direct applicability to business workflows without additional fine-tuning or wrapping.
For businesses, it is best suited to teams with the infrastructure to fine-tune or adapt large open-weight models for specific tasks. Its reasoning capability is competitive with mid-2024 proprietary models, but the 32K context window is a significant constraint for long-document analysis. The absence of agentic tooling means it cannot be dropped into agent pipelines without modification.
At $4 per million tokens for both input and output, it is not cheap for an open-weight model, especially given the infrastructure costs of running 405B parameters. Teams with specific open-weight requirements and the capability to adapt base models will find it powerful; others should consider instruction-tuned alternatives.
Assessed June 17, 2026
Editorial notes
Llama 3.1 405B base from Meta delivers strong reasoning and a broad benchmark profile, but lacks tool use and vision support, and its 32K context window limits long-document applications.
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Performance Profile
How Meta: Llama 3.1 405B (base) compares
Meta: Llama 3.1 405B (base) ranks #256 of 380 AI models we track for overall intelligence, #241 of 292 for agentic tasks. Its 33K-token context window is larger than 31% of the models we list. At $4.00 per million input tokens it is cheaper than 7% of comparable models.
About Meta: Llama 3.1 405B (base)
Meta's latest class of model (Llama 3.1) launched with a variety of sizes & flavors. This is the base 405B pre-trained version. It has demonstrated strong performance compared to leading closed-source models in human evaluations. Usage of this model is subject to Meta's Acceptable Use Policy.
Architecture Detail
| Instruct Type | none |
Performance Indices
Source: Artificial Analysis
Benchmark Scores
Intelligence
Technical
Content
Benchmark data from Artificial Analysis and Hugging Face
How does Meta: Llama 3.1 405B (base) stack up?
Compare side-by-side with other efficient models.
Model Information
| OpenRouter ID |
meta-llama/llama-3.1-405b
|
| Provider | meta-llama |
| Model Family | Llama 3 |
| Release Date | August 2, 2024 |
| Context Length | 32,768 tokens |
| Max Completion | 32,768 tokens |
| Status | Active |
Pricing
| Token Type | Cost per 1M tokens | Cost per 1K tokens |
|---|---|---|
| Input | $4.00 | $0.004000 |
| Output | $4.00 | $0.004000 |
Leaderboard Categories
External Resources
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Frequently asked questions about Meta: Llama 3.1 405B (base)
How much does Meta: Llama 3.1 405B (base) cost?
Meta: Llama 3.1 405B (base) costs $4.00 per million input tokens and $4.00 per million output tokens.
What is the context window of Meta: Llama 3.1 405B (base)?
Meta: Llama 3.1 405B (base) has a context window of 32,768 tokens (33K).
Who created Meta: Llama 3.1 405B (base)?
Meta: Llama 3.1 405B (base) is developed by Meta and was released on August 2, 2024.
Data sourced from OpenRouter API, Artificial Analysis and Hugging Face Open LLM Leaderboard. Scores are editorially curated by our team.
Last updated: June 19, 2026 8:38 pm