p-e-w · text · mixture of experts

gpt-oss-20b-heretic

p-e-w/gpt-oss-20b-heretic

gpt-oss-20b-heretic at Q4_K_M is exactly 15,805,137,056 bytes (14.72 GiB / 15.81 GB) — an effective 6.045 bits per weight, not the nominal 4. Its KV cache at 32K is 0.77 GiB, not the 1.50 GiB a flat formula predicts.

From the file· summed from 1 file(s)From the file· KV per layer
Parameters
20.9B
total, not active
Architecture
gpt-oss
24 layers
Context
131,072
native (config.json)
License
apache-2.0

Shipped quantizations

exact bytes, summed from published files
QuantSizeExact bytesEffective bpwTensorsPublisher
Q4_010.73 GiB11,519,189,9844.406bartowski
IQ4_NL10.77 GiB11,561,214,9444.422bartowski
Q4_110.80 GiB11,592,987,1044.434bartowski
Q3_K_S11.23 GiB12,061,090,9764.613mradermacher
Q2_K11.24 GiB12,065,514,6564.615mradermacher
Q8_011.28 GiB12,109,566,9444.632bartowski
IQ2_M11.31 GiB12,142,928,8644.645bartowski
Q3_K_S11.32 GiB12,151,776,2244.648bartowski
Q2_K11.32 GiB12,156,199,9044.650bartowski
IQ3_XS11.32 GiB12,156,199,9044.650bartowski
IQ3_XXS11.32 GiB12,156,199,9044.650bartowski
IQ4_XS11.32 GiB12,158,411,7444.651bartowski
IQ4_XS11.40 GiB12,245,779,6164.684mradermacher
Q2_K_L11.59 GiB12,445,766,6244.761bartowski
IQ3_M11.69 GiB12,554,331,1044.802bartowski
Q3_K_M11.69 GiB12,554,515,4244.802bartowski
Q3_K_L11.81 GiB12,682,617,8244.851bartowski
Q3_K_M12.03 GiB12,916,151,4564.941mradermacher
Q3_K_L12.42 GiB13,335,110,8165.101mradermacher
Q4_K_S13.65 GiB14,654,242,9765.605mradermacher
Q4_K_S13.83 GiB14,852,202,4645.681bartowski
Q4_K_M14.72 GiB15,805,137,0566.045mradermacher
Q4_K_M14.76 GiB15,853,797,3446.064bartowski
Q5_K_S14.80 GiB15,892,205,2166.079mradermacher
Q5_K_S14.81 GiB15,903,264,2246.083bartowski
Q4_K_L14.97 GiB16,070,972,3846.147bartowski
Q5_K_M15.73 GiB16,893,062,8166.462mradermacher
Q5_K_M15.74 GiB16,904,121,8246.466bartowski
Q5_K_L15.91 GiB17,085,101,0246.535bartowski
Q6_K_L20.67 GiB22,193,345,5048.489bartowski
Q6_K20.67 GiB22,193,345,5048.489bartowski
Q6_K20.67 GiB22,193,345,6968.489mradermacher
Q8_020.73 GiB22,261,912,7368.515mradermacher
BF1638.99 GiB41,860,888,28816.012bartowski
IQ4_NL6 shards67.58 GiB72,559,573,79227.754DavidAU
Q5_16 shards88.57 GiB95,097,440,032DavidAU
Q8_05 shards102.72 GiB110,296,079,200DavidAU

KV cache by context

computed per layer — this model uses sliding-window attention
ContextKV cache (f16)Flat formulaOverstated byFull / windowed / recurrent
4,0960.11 GiB0.19 GiB1.68×12 / 12 / 0
8,1920.21 GiB0.38 GiB1.83×12 / 12 / 0
16,3840.39 GiB0.75 GiB1.91×12 / 12 / 0
32,7680.77 GiB1.50 GiB1.95×12 / 12 / 0
65,5361.52 GiB3.00 GiB1.98×12 / 12 / 0
131,0723.02 GiB6.00 GiB1.99×12 / 12 / 0

12 of 24 layers cache only a 128-token window rather than the full context, on a period of . Figures assume the default configuration; --swa-full disables the saving entirely.

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 10.96 GiB. The real file is 14.72 GiB, because a quantization is a mixture and some tensors are always kept at higher precision. The larger discrepancy is the cache: a flat formula gives 1.50 GiB at 32K context where the real figure is 0.77 GiB, because most of this model's layers cache a fixed window rather than the whole context.

Architecture

from config.json
Layers
24
Attention heads
64
KV heads
8
Head dim
64
Hidden size
2880
Vocab
201,088
Sliding window
128
SWA period
MLA
no
Experts
32
Experts per token
4
use_sliding_window

Questions people ask

How much VRAM does gpt-oss-20b-heretic need?
Q4_K_M is exactly 15,805,137,056 bytes (14.72 GiB) in weights. Add the KV cache, which depends on your context length, plus roughly half a gigabyte of runtime overhead.
How large is gpt-oss-20b-heretic's KV cache?
0.77 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.
Is gpt-oss-20b-heretic a mixture-of-experts model?
Yes — 32 experts, 4 routed per token. Every expert must be resident, but only the routed ones are read per token, which is why its memory requirement and its speed behave very differently.
Which quantization of gpt-oss-20b-heretic 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.