Llama 3.1 405B — Hardware Requirements & GPU Compatibility
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Meta Llama 3.1 405B is the largest model in the Llama family with 405 billion parameters. It represents Meta's most capable open-weight model, delivering performance competitive with leading proprietary models across reasoning, coding, math, and multilingual tasks. It features a 128K token context window. Due to its massive size, running Llama 3.1 405B locally requires significant hardware, typically multiple high-end professional GPUs with a combined VRAM of 200GB or more at reduced precision. It is primarily used in quantized formats for local inference or via multi-node setups. Released under the Llama 3.1 Community License.
514.6K downloads
965 likesSpecifications
- Publisher
- Meta
- Family
- Llama 3
- Parameters
- 405B
- Release Date
- 2024-09-25
- License
- Llama 3.1 Community
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HuggingFace
How Much VRAM Does Llama 3.1 405B Need?
Select a quantization to see compatible GPUs below.
| Quantization | Bits | VRAM | + Context | File Size | Quality |
|---|---|---|---|---|---|
| BF16 | 16.00 | 891 GB | — | 810.00 GB | Brain floating point 16 — preferred for training |
Which GPUs Can Run Llama 3.1 405B?
BF16 · 891 GBLlama 3.1 405B (BF16) requires 891 GB of VRAM to load the model weights. For comfortable inference with headroom for KV cache and system overhead, 1159+ GB is recommended. No single GPU has enough memory — multi-GPU or cluster setups are needed.
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Frequently Asked Questions
- How much VRAM does Llama 3.1 405B need?
Llama 3.1 405B requires 891 GB of VRAM at BF16.
VRAM = Weights + KV Cache + Overhead
Weights = 405B × 16 bits ÷ 8 = 810 GB
KV Cache + Overhead ≈ 81 GB (at 2K context + ~0.3 GB framework)
VRAM usage by quantization
BF16891.0 GB- Can NVIDIA GeForce RTX 5090 run Llama 3.1 405B?
No — Llama 3.1 405B requires at least 891 GB at BF16, which exceeds the NVIDIA GeForce RTX 5090's 32 GB of VRAM.
- Can I run Llama 3.1 405B on a Mac?
Llama 3.1 405B requires at least 891 GB at BF16, which exceeds the unified memory of most consumer Macs. You would need a Mac Studio or Mac Pro with a high-memory configuration.
- Can I run Llama 3.1 405B locally?
Yes — Llama 3.1 405B can run locally on consumer hardware. At BF16 quantization it needs 891 GB of VRAM. Popular tools include Ollama, LM Studio, and llama.cpp.
- What's the download size of Llama 3.1 405B?
At BF16, the download is about 810.00 GB.