migtissera · vision language

Tess-4-27B

migtissera/Tess-4-27B

Tess-4-27B at Q4_K_M is exactly 17,772,536,480 bytes (16.55 GiB / 17.77 GB) — an effective 5.118 bits per weight, not the nominal 4. Its KV cache at 32K is 2.00 GiB.

From the file· summed from 1 file(s)From the file· KV per layer
Parameters
27.8B
Architecture
qwen35
64 layers
Context
262,144
native (config.json)
License
apache-2.0

Shipped quantizations

exact bytes, summed from published files
QuantSizeExact bytesEffective bpwTensorsPublisher
IQ2_XXS8.75 GiB9,393,042,0802.705bartowski
IQ2_XS9.30 GiB9,986,798,2402.876bartowski
IQ2_S9.59 GiB10,295,329,4402.965bartowski
IQ2_M10.13 GiB10,873,356,9603.131bartowski
Q2_K11.03 GiB11,839,439,5203.409bartowski
IQ3_XXS11.76 GiB12,626,772,6403.636bartowski
Q2_K_L12.18 GiB13,081,039,5203.767bartowski
IQ3_XS12.41 GiB13,330,404,0003.839bartowski
Q3_K_S12.78 GiB13,720,343,2003.951bartowski
IQ3_M12.95 GiB13,903,516,3204.004bartowski
Q3_K_M13.60 GiB14,605,734,5604.206866bartowski
Q3_K_L14.23 GiB15,279,444,6404.400bartowski
IQ4_XS14.50 GiB15,567,823,5204.483866bartowski
IQ4_NL15.20 GiB16,325,829,2804.701bartowski
Q4_015.23 GiB16,348,766,8804.708866bartowski
Q4_K_S15.57 GiB16,713,147,0404.813bartowski
Q4_K_M16.55 GiB17,772,536,4805.118bartowski
Q4_116.60 GiB17,825,456,8005.133bartowski
Q4_K_M2 shards17.30 GiB18,579,782,0805.350migtissera
Q4_K_L17.43 GiB18,716,152,4805.389bartowski
Q5_K_S18.33 GiB19,680,944,8005.667bartowski
Q5_K_M19.33 GiB20,752,786,0805.976866bartowski
Q5_K_L20.06 GiB21,537,477,2806.202bartowski
Q6_K20.57 GiB22,082,528,2566.359migtissera
Q6_K21.85 GiB23,463,129,7606.756866bartowski
Q6_K_L22.43 GiB24,078,963,3606.934bartowski
Q8_027.12 GiB29,116,388,0008.384866bartowski
Q8_02 shards29.58 GiB31,759,768,0009.146migtissera
BF162 shards50.90 GiB54,657,733,21615.739bartowski

KV cache by context

computed per layer
ContextKV cache (f16)Flat formulaOverstated byFull / windowed / recurrent
4,0960.25 GiB1.00 GiB4.00×16 / 0 / 48
8,1920.50 GiB2.00 GiB4.00×16 / 0 / 48
16,3841.00 GiB4.00 GiB4.00×16 / 0 / 48
32,7682.00 GiB8.00 GiB4.00×16 / 0 / 48
65,5364.00 GiB16.00 GiB4.00×16 / 0 / 48
131,0728.00 GiB32.00 GiB4.00×16 / 0 / 48

48 of 64 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 14.55 GiB. The real file is 16.55 GiB, because a quantization is a mixture and some tensors are always kept at higher precision.

Architecture

from config.json
Layers
64
Attention heads
24
KV heads
4
Head dim
256
Hidden size
5120
Vocab
248,320
Sliding window
none
SWA period
MLA
no
Experts
Experts per token
use_sliding_window

Questions people ask

How much VRAM does Tess-4-27B need?
Q4_K_M is exactly 17,772,536,480 bytes (16.55 GiB) in weights. Add the KV cache, which depends on your context length, plus roughly half a gigabyte of runtime overhead.
How large is Tess-4-27B's KV cache?
2.00 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 Tess-4-27B 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.