How much VRAM does Qwen2.5-3B need?

Q4_K_M is exactly 1,929,900,480 bytes (1.80 GiB) in weights. Add the KV cache, which depends on context length, plus roughly half a gigabyte of runtime overhead.

How large is Qwen2.5-3B's KV cache?

1.13 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.

Qwen · text

Qwen2.5-3B

Qwen/Qwen2.5-3B

Qwen2.5-3B at Q4_K_M is exactly 1,929,900,480 bytes (1.80 GiB / 1.93 GB) — an effective 5.003 bits per weight, not the nominal 4. Its KV cache at 32K is 1.13 GiB.

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

Parameters

3.1B

Architecture

qwen2

36 layers

Context

32,768

native (config.json)

License

—

Shipped quantizations

● exact bytes, summed from published files

Quant	Size●	Exact bytes●	Effective bpw●	Tensors●	Publisher
IQ1_S	0.74 GiB	791,094,400	2.051	—	ThomasBaruzier
IQ1_M	0.79 GiB	850,027,648	2.204	—	ThomasBaruzier
IQ2_XXS	0.88 GiB	948,249,728	2.458	—	ThomasBaruzier
IQ2_XS	0.96 GiB	1,031,545,984	2.674	—	ThomasBaruzier
IQ2_S	0.99 GiB	1,061,938,304	2.753	—	ThomasBaruzier
IQ2_M	1.06 GiB	1,140,515,968	2.957	—	ThomasBaruzier
Q2_K_S	1.12 GiB	1,198,128,256	3.106	—	ThomasBaruzier
Q2_K	1.19 GiB	1,274,756,224	3.305	—	ThomasBaruzier
IQ3_XXS	1.19 GiB	1,282,827,392	3.326	—	ThomasBaruzier
Q2_K	1.28 GiB	1,376,859,904	3.569	—	QuantFactory
IQ3_XS	1.30 GiB	1,391,836,288	3.608	—	ThomasBaruzier
Q3_K_S	1.35 GiB	1,454,357,632	3.770	—	ThomasBaruzier
IQ3_S	1.36 GiB	1,456,864,384	3.777	—	ThomasBaruzier
IQ3_M	1.39 GiB	1,488,892,352	3.860	—	bartowski
IQ3_M	1.39 GiB	1,488,895,104	3.860	—	ThomasBaruzier
Q3_K_S	1.48 GiB	1,588,064,000	4.117	—	QuantFactory
Q3_K_M	1.48 GiB	1,590,475,904	4.123	—	ThomasBaruzier
Q3_K_L	1.59 GiB	1,707,389,376	4.426	—	bartowski
Q3_K_L	1.59 GiB	1,707,392,128	4.426	—	ThomasBaruzier
Q3_K_M	1.61 GiB	1,724,182,272	4.470	—	QuantFactory
IQ4_XS	1.62 GiB	1,739,092,416	4.508	—	bartowski
IQ4_XS	1.62 GiB	1,739,095,168	4.508	—	ThomasBaruzier
IQ4_NL	1.70 GiB	1,825,209,472	4.732	—	ThomasBaruzier
Q4_0	1.70 GiB	1,828,483,520	4.740	—	bartowski
Q4_0	1.70 GiB	1,828,486,272	4.740	—	ThomasBaruzier
Q4_K_S	1.71 GiB	1,834,381,760	4.755	—	bartowski
Q4_K_S	1.71 GiB	1,834,384,512	4.755	—	ThomasBaruzier
Q3_K_L	1.71 GiB	1,841,098,496	4.773	—	QuantFactory
Q4_K_M	1.80 GiB	1,929,900,480	5.003	—	bartowski
Q4_K_M	1.80 GiB	1,929,903,232	5.003	—	ThomasBaruzier
Q4_1	1.86 GiB	1,996,258,432	5.175	—	ThomasBaruzier
Q4_0	1.86 GiB	1,997,883,136	5.179	—	QuantFactory
Q4_K_L	1.87 GiB	2,005,260,736	5.198	—	bartowski
Q4_K_S	1.87 GiB	2,009,417,472	5.209	—	QuantFactory
Q4_K_M	1.96 GiB	2,104,936,192	5.457	—	QuantFactory
Q5_K_S	2.02 GiB	2,169,663,936	5.625	—	bartowski
Q5_K_S	2.02 GiB	2,169,666,688	5.625	—	ThomasBaruzier
Q5_0	2.03 GiB	2,175,302,784	5.639	—	ThomasBaruzier
Q4_1	2.04 GiB	2,190,739,200	5.679	—	QuantFactory
Q5_K_M	2.07 GiB	2,224,812,480	5.768	—	bartowski

KV cache by context

computed per layer

Context	KV cache (f16)●	Flat formula	Overstated by	Full / windowed / recurrent
4,096	0.14 GiB	0.14 GiB	—	36 / 0 / 0
8,192	0.28 GiB	0.28 GiB	—	36 / 0 / 0
16,384	0.56 GiB	0.56 GiB	—	36 / 0 / 0
32,768	1.13 GiB	1.13 GiB	—	36 / 0 / 0
65,536	2.25 GiB	2.25 GiB	—	36 / 0 / 0
131,072	4.50 GiB	4.50 GiB	—	36 / 0 / 0

Compare with

same modality, comparable size

vs Qwen3-4B vs HyperCLOVAX-SEED-Text-Instruct-1.5B vs Llama-3.2-1B-Instruct vs ced-base vs gemma-3-1b-it vs Qwen3-1.7B 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 1.62 GiB. The real file is 1.80 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

2048

Vocab

151,936

Sliding window

32768

SWA period

—

MLA

Experts

—

Experts per token

—

use_sliding_window

false

This model declares a sliding window but sets use_sliding_window: false, so the window is not applied. Honouring the field without the flag understates KV for the whole family.

Questions people ask

How much VRAM does Qwen2.5-3B need?: Q4_K_M is exactly 1,929,900,480 bytes (1.80 GiB) in weights. Add the KV cache, which depends on your context length, plus roughly half a gigabyte of runtime overhead.
How large is Qwen2.5-3B's KV cache?: 1.13 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 Qwen2.5-3B 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.