How much VRAM does granite-4.1-8b need?

Q4_K_M is exactly 5,347,914,400 bytes (4.98 GiB) in weights. Add the KV cache, which depends on context length, plus roughly half a gigabyte of runtime overhead.

How large is granite-4.1-8b's KV cache?

5.00 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.

ibm-granite · text

granite-4.1-8b

ibm-granite/granite-4.1-8b

granite-4.1-8b at Q4_K_M is exactly 5,347,914,400 bytes (4.98 GiB / 5.35 GB) — an effective 4.866 bits per weight, not the nominal 4. Its KV cache at 32K is 5.00 GiB.

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

Parameters

8.8B

Architecture

—

40 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
UD-IQ2_M	3.05 GiB	3,272,078,720	2.978	—	unsloth
Q2_K	3.18 GiB	3,412,308,640	3.105	—	ibm-granite
UD-IQ3_XXS	3.36 GiB	3,606,148,480	3.281	—	unsloth
Q3_K_S	3.67 GiB	3,942,953,632	3.588	—	ibm-granite
Q3_K_S	3.67 GiB	3,942,954,368	3.588	—	unsloth
Q3_K_M	4.05 GiB	4,347,048,608	3.956	—	ibm-granite
Q3_K_M	4.05 GiB	4,347,049,344	3.956	—	unsloth
Q3_K_L	4.38 GiB	4,699,894,432	4.277	—	ibm-granite
IQ4_XS	4.50 GiB	4,833,129,856	4.398	—	unsloth
Q4_0	4.71 GiB	5,055,951,520	4.601	—	ibm-granite
Q4_0	4.72 GiB	5,072,336,256	4.616	—	unsloth
IQ4_NL	4.73 GiB	5,076,923,776	4.620	—	unsloth
Q4_K_S	4.74 GiB	5,090,816,672	4.632	—	ibm-granite
Q4_K_S	4.74 GiB	5,090,817,408	4.632	—	unsloth
Q4_K_M	4.98 GiB	5,347,914,400	4.866	—	ibm-granite
Q4_K_M	4.98 GiB	5,347,915,136	4.866	—	unsloth
Q4_1	5.20 GiB	5,579,715,232	5.077	—	ibm-granite
Q4_1	5.20 GiB	5,579,715,968	5.077	—	unsloth
Q5_0	5.68 GiB	6,103,478,944	5.554	—	ibm-granite
Q5_K_S	5.68 GiB	6,103,478,944	5.554	—	ibm-granite
Q5_K_S	5.68 GiB	6,103,479,680	5.554	—	unsloth
Q5_K_M	5.82 GiB	6,253,884,064	5.691	—	ibm-granite
Q5_K_M	5.82 GiB	6,253,884,800	5.691	—	unsloth
Q5_1	6.17 GiB	6,627,242,656	6.030	—	ibm-granite
Q6_K	6.72 GiB	7,216,476,832	6.567	—	ibm-granite
Q6_K	6.72 GiB	7,216,477,568	6.567	—	unsloth
Q8_0	8.70 GiB	9,345,610,400	8.504	—	ibm-granite
Q8_0	8.70 GiB	9,345,611,136	8.504	—	unsloth
BF16	16.38 GiB	17,587,417,760	16.004	—	ibm-granite
BF16	16.38 GiB	17,587,418,240	16.004	—	unsloth

KV cache by context

computed per layer

Context	KV cache (f16)●	Flat formula	Overstated by	Full / windowed / recurrent
4,096	0.63 GiB	0.63 GiB	—	40 / 0 / 0
8,192	1.25 GiB	1.25 GiB	—	40 / 0 / 0
16,384	2.50 GiB	2.50 GiB	—	40 / 0 / 0
32,768	5.00 GiB	5.00 GiB	—	40 / 0 / 0
65,536	10.00 GiB	10.00 GiB	—	40 / 0 / 0
131,072	20.00 GiB	20.00 GiB	—	40 / 0 / 0

Compare with

same modality, comparable size

vs Qwen3-Coder-30B-A3B-Instruct vs gemma-4-12B-it-qat-q4_0-unquantized vs Llama-3.2-1B-Instruct vs llama-3-youko-8b vs Qwen3-8B vs Qwen3-VL-8B-Instruct-abliterated-v1 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 4.61 GiB. The real file is 4.98 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

100,352

Sliding window

none

SWA period

—

MLA

Experts

—

Experts per token

—

use_sliding_window

—

Questions people ask

How much VRAM does granite-4.1-8b need?: Q4_K_M is exactly 5,347,914,400 bytes (4.98 GiB) in weights. Add the KV cache, which depends on your context length, plus roughly half a gigabyte of runtime overhead.
How large is granite-4.1-8b's KV cache?: 5.00 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 granite-4.1-8b 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.