How much VRAM does granite-3.1-8b-instruct need?

Q4_K_M is exactly 4,899,475,200 bytes (4.56 GiB) in weights. Add the KV cache, which depends on context length, plus roughly half a gigabyte of runtime overhead.

How large is granite-3.1-8b-instruct'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-3.1-8b-instruct

ibm-granite/granite-3.1-8b-instruct

granite-3.1-8b-instruct at Q4_K_M is exactly 4,899,475,200 bytes (4.56 GiB / 4.90 GB) — an effective 4.797 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

8.2B

Architecture

granite

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
TQ1_0	1.72 GiB	1,849,232,960	1.811	—	Mungert
TQ2_0	2.07 GiB	2,222,788,160	2.176	—	Mungert
IQ2_XXS	2.29 GiB	2,463,434,912	2.412	—	Mungert
IQ2_XS	2.50 GiB	2,689,534,112	2.633	—	Mungert
IQ2_S	2.60 GiB	2,788,493,472	2.730	—	Mungert
IQ2_M	2.64 GiB	2,836,824,960	2.777	—	bartowski
IQ2_M	2.73 GiB	2,935,294,112	2.874	—	Mungert
Q2_K_S	2.82 GiB	3,029,403,808	2.966	—	Mungert
Q2_K_M	2.85 GiB	3,056,144,128	2.992	—	Mungert
Q2_K	2.89 GiB	3,103,590,880	3.039	—	bartowski
Q2_K_L	2.94 GiB	3,152,352,640	3.086	—	bartowski
IQ3_XXS	3.10 GiB	3,323,398,304	3.254	—	Mungert
IQ3_XS	3.19 GiB	3,424,979,104	3.353	—	Mungert
IQ3_XS	3.19 GiB	3,427,994,080	3.356	—	bartowski
Q3_K_S	3.35 GiB	3,592,489,440	3.517	—	bartowski
IQ3_M	3.48 GiB	3,738,716,640	3.660	—	bartowski
IQ3_S	3.56 GiB	3,823,569,056	3.744	—	Mungert
IQ3_M	3.56 GiB	3,823,569,056	3.744	—	Mungert
Q3_K_S	3.67 GiB	3,938,912,416	3.857	—	Mungert
Q3_K_M	3.69 GiB	3,965,652,736	3.883	—	Mungert
Q3_K_M	3.72 GiB	3,996,584,416	3.913	—	bartowski
Q3_K_L	4.05 GiB	4,349,429,952	4.258	—	lmstudio-community
Q3_K_L	4.05 GiB	4,349,430,240	4.258	—	bartowski
IQ4_XS	4.12 GiB	4,428,073,440	4.335	—	bartowski
IQ4_XS	4.12 GiB	4,428,074,752	4.335	—	Mungert
Q4_0	4.28 GiB	4,598,989,472	4.503	—	Mungert
Q4_0	4.35 GiB	4,667,279,840	4.570	—	bartowski
IQ4_NL	4.35 GiB	4,671,867,360	4.574	—	bartowski
IQ4_NL	4.35 GiB	4,671,868,672	4.574	—	Mungert
Q4_K_S	4.36 GiB	4,685,760,992	4.588	—	bartowski
Q4_K_S	4.41 GiB	4,730,851,072	4.632	—	Mungert
Q4_K_M	4.56 GiB	4,899,475,200	4.797	—	Mungert
Q4_K_M	4.60 GiB	4,942,858,432	4.840	—	lmstudio-community
Q4_K_M	4.60 GiB	4,942,858,720	4.840	—	bartowski
Q4_K_L	4.65 GiB	4,991,620,480	4.887	—	bartowski
Q4_1	4.76 GiB	5,109,646,752	5.003	—	Mungert
Q5_0	5.23 GiB	5,620,304,032	5.503	—	Mungert
Q5_K_S	5.26 GiB	5,647,043,040	5.529	—	bartowski
Q5_K_S	5.33 GiB	5,725,032,192	5.605	—	Mungert
Q5_K_M	5.40 GiB	5,797,448,160	5.676	—	bartowski

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 gemma-4-E4B-it vs Qwen3-4B vs Qwen3-8B vs HyperCLOVAX-SEED-Text-Instruct-1.5B vs Llama-3.2-1B-Instruct 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 4.28 GiB. The real file is 4.56 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

49,155

Sliding window

none

SWA period

—

MLA

Experts

—

Experts per token

—

use_sliding_window

—

Questions people ask

How much VRAM does granite-3.1-8b-instruct need?: Q4_K_M is exactly 4,899,475,200 bytes (4.56 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-3.1-8b-instruct'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-3.1-8b-instruct 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.