How much VRAM does Meta-Llama-3.1-8B need?

Q4_K_M is exactly 4,920,734,176 bytes (4.58 GiB) in weights. Add the KV cache, which depends on context length, plus roughly half a gigabyte of runtime overhead.

How large is Meta-Llama-3.1-8B's KV cache?

4.00 GiB at 32K context with an f16 cache, computed per layer from the model's architecture. Quantizing the cache to q8_0 roughly halves it.

unsloth · text

Meta-Llama-3.1-8B

unsloth/Meta-Llama-3.1-8B

Meta-Llama-3.1-8B at Q4_K_M is exactly 4,920,734,176 bytes (4.58 GiB / 4.92 GB) — an effective 4.902 bits per weight, not the nominal 4. Its KV cache at 32K is 4.00 GiB.

From the file· summed from 1 file(s)From the file· KV per layer

Parameters

8.0B

Architecture

llama

32 layers

Context

131,072

native (config.json)

License

apache-2.0

Shipped quantizations

● exact bytes, summed from published files

Quant	Size●	Exact bytes●	Effective bpw●	Tensors●	Publisher
Q2_K	2.96 GiB	3,179,131,360	3.167	—	large-traversaal
Q3_K_M	3.74 GiB	4,018,917,856	4.004	—	large-traversaal
Q4_K_M	4.58 GiB	4,920,734,176	4.902	—	large-traversaal
Q4_K_M	4.58 GiB	4,920,734,368	4.902	—	agurusantosh
Q4_K_M	4.58 GiB	4,920,734,368	4.902	—	agurusantosh
Q5_K_M	5.34 GiB	5,732,987,360	5.711	—	large-traversaal
Q6_K	6.14 GiB	6,596,006,368	6.571	—	large-traversaal
Q8_0	7.95 GiB	8,540,770,784	8.509	—	large-traversaal
F16	14.97 GiB	16,068,891,104	16.008	—	large-traversaal

KV cache by context

computed per layer

Context	KV cache (f16)●	Flat formula	Overstated by	Full / windowed / recurrent
4,096	0.50 GiB	0.50 GiB	—	32 / 0 / 0
8,192	1.00 GiB	1.00 GiB	—	32 / 0 / 0
16,384	2.00 GiB	2.00 GiB	—	32 / 0 / 0
32,768	4.00 GiB	4.00 GiB	—	32 / 0 / 0
65,536	8.00 GiB	8.00 GiB	—	32 / 0 / 0
131,072	16.00 GiB	16.00 GiB	—	32 / 0 / 0

Compare with

same modality, comparable size

vs gemma-4-12B-it-qat-q4_0-unquantized vs gemma-4-E4B-it vs Qwen3-30B-A3B-Thinking-2507 vs Qwen3-4B vs Qwen3-8B vs Llama-3.2-1B-Instruct All alternatives →Will it fit on my card? →

Why other calculators give a different number

A parameters × bits ÷ 8 estimate puts Q4_K_M at roughly 4.21 GiB. The real file is 4.58 GiB, because a quantization is a mixture and some tensors are always kept at higher precision.

Architecture

from config.json

Layers

Attention heads

KV heads

Head dim

128

Hidden size

4096

Vocab

128,256

Sliding window

none

SWA period

—

MLA

Experts

—

Experts per token

—

use_sliding_window

—

Questions people ask

How much VRAM does Meta-Llama-3.1-8B need?: Q4_K_M is exactly 4,920,734,176 bytes (4.58 GiB) in weights. Add the KV cache, which depends on your context length, plus roughly half a gigabyte of runtime overhead.
How large is Meta-Llama-3.1-8B's KV cache?: 4.00 GiB at 32K context with an f16 cache, computed per layer. Quantizing the cache to q8_0 roughly halves it, which is often the difference between a context length fitting and not.
Which quantization of Meta-Llama-3.1-8B should I use?: Q4_K_M is the usual default. Pick the largest quantization that fits your card at the context you actually need — the table above gives exact sizes for every one published.