Meta's largest open-weights model, competitive with frontier closed models.

Key specifications

Intelligence
74.0
Capability
34.2
Context window
128K
Max output
4.1K
Output speed
30 t/s
Latency (TTFT)
0.70s
Input $/1M
$3.50
Output $/1M
$3.50
License
Llama 3.1 Community
Architecture
Transformer (dense)
Parameters
405B

Inputs and outputs

Recorded modality support shows what this model can accept and produce. An undocumented modality is shown as unknown rather than assumed to be unsupported.

Accepts

  • Text input

Produces

  • Text output

Capabilities

Function callingStreamingJSON modeFine-tuningOpen weights

What is Llama 3.1 405B?

Editorial review for Llama 3.1 405B

Llama 3.1 405B is a Meta model retained in SyncDev’s public directory. This record now links to an authoritative source so readers can distinguish documented facts from information that changes over time. The editorial summary does not infer a current price, API route, benchmark result, regional availability, or feature guarantee from a historical model name.

What to verify before choosing it

Use the linked first-party documentation to confirm the current interface, supported modalities, context and output limits, safety requirements, service availability, and commercial terms. Those details can change independently of this directory. For a production decision, test representative prompts, tool calls, latency targets, multilingual needs, and reliability requirements with the provider’s current release.

Comparison guidance

A useful comparison starts with the workload, not a generic winner. Compare the model against alternatives using the same prompts, token budgets, evaluation rubric, deployment region, and cost assumptions. Where this page does not show a verified measurement, treat it as unknown rather than filling the gap with an estimate.

Source and update policy

SyncDev keeps this page live as an editorial overview and retains the source link for future review. Editors must refresh material claims from first-party documentation before changing the page, publishing a comparison, or adding it to a search sitemap.

How to evaluate Llama 3.1 405B

Use the recorded facts as a shortlist, then validate the model against representative inputs and production constraints.

Workload fit

Llama 3.1 405B is categorized for Text generation, Text-to-text AI models. Its current record accepts text and produces text. Confirm file formats, preprocessing, and provider-specific request schemas before implementation.

Capacity and cost

The directory records 128K context and 4.1K maximum output. Listed token prices are $3.50 input and $3.50 output per 1M tokens. Treat missing values as unknown and recheck current commercial terms.

Operational behavior

Recorded output speed is 30 t/s and time to first token is 0.70s. Hosting route, region, prompt length, concurrency, and provider load can materially change both measurements.

Evidence boundary

This page separates sourced model facts from incomplete fields. Benchmark evidence is displayed only when its source is linked and verified. Before choosing Llama 3.1 405B, test task quality, tool reliability, safety behavior, data controls, rate limits, and total cost on the exact route you intend to use.

Strengths

  • + Open weights — self-hostable
  • + Strong general performance

Limitations

  • Heavy to run
  • Slower hosted throughput

Benchmark results

Each score below comes from a published result we could trace back to its source. Read them as evidence about the specific task a benchmark measures — a model that leads on one can easily trail on another.

No benchmark results recorded for this model yet. Add them with a source link and this section appears on the live page.

Frequently asked questions

Llama 3.1 405B is a Meta model in SyncDev’s directory. Use the linked primary source to confirm current product details.

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