Merlin-Research · text

Qwen3.5-4B-Safety-Thinking

Merlin-Research/Qwen3.5-4B-Safety-Thinking

Qwen3.5-4B-Safety-Thinking at Q4_K_M is exactly 2,707,514,688 bytes (2.52 GiB / 2.71 GB) — an effective 5.150 bits per weight, not the nominal 4. Its KV cache at 32K is 1.00 GiB.

From the file· summed from 1 file(s)From the file· KV per layer
Parameters
4.2B
Architecture
qwen35
32 layers
Context
262,144
native (config.json)
License
apache-2.0

Shipped quantizations

exact bytes, summed from published files
QuantSizeExact bytesEffective bpwTensorsPublisher
I1-IQ1_S1.09 GiB1,174,423,1362.234mradermacher
I1-IQ1_M1.17 GiB1,253,404,2562.384mradermacher
I1-IQ2_XXS1.29 GiB1,385,039,4562.635mradermacher
I1-IQ2_XS1.39 GiB1,492,969,0562.840mradermacher
I1-IQ2_S1.41 GiB1,514,350,1762.881mradermacher
I1-IQ2_M1.51 GiB1,619,658,3363.081mradermacher
I1-Q2_K_S1.62 GiB1,734,428,2563.299mradermacher
Q2_K1.67 GiB1,797,506,3683.419mradermacher
I1-Q2_K1.67 GiB1,797,506,6563.419mradermacher
I1-IQ3_XXS1.69 GiB1,814,054,4963.451mradermacher
I1-IQ3_XS1.87 GiB2,010,734,1763.825mradermacher
Q3_K_S1.93 GiB2,069,880,1283.937mradermacher
I1-Q3_K_S1.93 GiB2,069,880,4163.937mradermacher
I1-IQ3_S1.93 GiB2,072,665,6963.942mradermacher
I1-IQ3_M2.01 GiB2,163,187,2964.115mradermacher
Q3_K_M2.10 GiB2,257,476,9284.294mradermacher
I1-Q3_K_M2.10 GiB2,257,477,2164.294mradermacher
Q3_K_L2.20 GiB2,358,402,3684.486mradermacher
I1-Q3_K_L2.20 GiB2,358,402,6564.486mradermacher
I1-IQ4_XS2.27 GiB2,435,642,9764.633mradermacher
IQ4_XS2.28 GiB2,450,388,2884.661mradermacher
I1-IQ4_NL2.37 GiB2,546,521,6964.844mradermacher
I1-Q4_02.37 GiB2,549,798,4964.850mradermacher
Q4_K_S2.38 GiB2,557,007,1684.864mradermacher
I1-Q4_K_S2.38 GiB2,557,007,4564.864mradermacher
Q4_K_M2.52 GiB2,707,514,6885.150mradermacher
I1-Q4_K_M2.52 GiB2,707,514,9765.150mradermacher
I1-Q4_12.58 GiB2,766,968,4165.263mradermacher
Q5_K_S2.78 GiB2,990,036,2885.688mradermacher
I1-Q5_K_S2.78 GiB2,990,036,5765.688mradermacher
Q5_K_M2.90 GiB3,108,758,8485.913mradermacher
I1-Q5_K_M2.90 GiB3,108,759,1365.913mradermacher
Q6_K3.23 GiB3,464,056,1286.589mradermacher
I1-Q6_K3.23 GiB3,464,056,4166.589mradermacher
Q8_04.17 GiB4,482,403,6488.526mradermacher
F167.85 GiB8,424,394,04816.024mradermacher

KV cache by context

computed per layer
ContextKV cache (f16)Flat formulaOverstated byFull / windowed / recurrent
4,0960.13 GiB0.50 GiB4.00×8 / 0 / 24
8,1920.25 GiB1.00 GiB4.00×8 / 0 / 24
16,3840.50 GiB2.00 GiB4.00×8 / 0 / 24
32,7681.00 GiB4.00 GiB4.00×8 / 0 / 24
65,5362.00 GiB8.00 GiB4.00×8 / 0 / 24
131,0724.00 GiB16.00 GiB4.00×8 / 0 / 24

24 of 32 layers use linear attention, which keeps a fixed-size recurrent state instead of a per-token cache. Those layers do not grow with context at all — treating them as ordinary attention, as a flat formula does, overstates this model's cache by roughly 4.0× at long context.

Compare with

same modality, comparable size

Will it run on your card?

full quant x context sweep

Why other calculators give a different number

A parameters × bits ÷ 8 estimate puts Q4_K_M at roughly 2.20 GiB. The real file is 2.52 GiB, because a quantization is a mixture and some tensors are always kept at higher precision.

Architecture

from config.json
Layers
32
Attention heads
16
KV heads
4
Head dim
256
Hidden size
2560
Vocab
248,320
Sliding window
none
SWA period
MLA
no
Experts
Experts per token
use_sliding_window

Questions people ask

How much VRAM does Qwen3.5-4B-Safety-Thinking need?
Q4_K_M is exactly 2,707,514,688 bytes (2.52 GiB) in weights. Add the KV cache, which depends on your context length, plus roughly half a gigabyte of runtime overhead.
How large is Qwen3.5-4B-Safety-Thinking's KV cache?
1.00 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 Qwen3.5-4B-Safety-Thinking 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.