gpt-oss-20b-heretic
p-e-w/gpt-oss-20b-hereticgpt-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.
Shipped quantizations
| Quant | Size● | Exact bytes● | Effective bpw● | Tensors● | Publisher |
|---|---|---|---|---|---|
| Q4_0 | 10.73 GiB | 11,519,189,984 | 4.406 | — | bartowski |
| IQ4_NL | 10.77 GiB | 11,561,214,944 | 4.422 | — | bartowski |
| Q4_1 | 10.80 GiB | 11,592,987,104 | 4.434 | — | bartowski |
| Q3_K_S | 11.23 GiB | 12,061,090,976 | 4.613 | — | mradermacher |
| Q2_K | 11.24 GiB | 12,065,514,656 | 4.615 | — | mradermacher |
| Q8_0 | 11.28 GiB | 12,109,566,944 | 4.632 | — | bartowski |
| IQ2_M | 11.31 GiB | 12,142,928,864 | 4.645 | — | bartowski |
| Q3_K_S | 11.32 GiB | 12,151,776,224 | 4.648 | — | bartowski |
| Q2_K | 11.32 GiB | 12,156,199,904 | 4.650 | — | bartowski |
| IQ3_XS | 11.32 GiB | 12,156,199,904 | 4.650 | — | bartowski |
| IQ3_XXS | 11.32 GiB | 12,156,199,904 | 4.650 | — | bartowski |
| IQ4_XS | 11.32 GiB | 12,158,411,744 | 4.651 | — | bartowski |
| IQ4_XS | 11.40 GiB | 12,245,779,616 | 4.684 | — | mradermacher |
| Q2_K_L | 11.59 GiB | 12,445,766,624 | 4.761 | — | bartowski |
| IQ3_M | 11.69 GiB | 12,554,331,104 | 4.802 | — | bartowski |
| Q3_K_M | 11.69 GiB | 12,554,515,424 | 4.802 | — | bartowski |
| Q3_K_L | 11.81 GiB | 12,682,617,824 | 4.851 | — | bartowski |
| Q3_K_M | 12.03 GiB | 12,916,151,456 | 4.941 | — | mradermacher |
| Q3_K_L | 12.42 GiB | 13,335,110,816 | 5.101 | — | mradermacher |
| Q4_K_S | 13.65 GiB | 14,654,242,976 | 5.605 | — | mradermacher |
| Q4_K_S | 13.83 GiB | 14,852,202,464 | 5.681 | — | bartowski |
| Q4_K_M | 14.72 GiB | 15,805,137,056 | 6.045 | — | mradermacher |
| Q4_K_M | 14.76 GiB | 15,853,797,344 | 6.064 | — | bartowski |
| Q5_K_S | 14.80 GiB | 15,892,205,216 | 6.079 | — | mradermacher |
| Q5_K_S | 14.81 GiB | 15,903,264,224 | 6.083 | — | bartowski |
| Q4_K_L | 14.97 GiB | 16,070,972,384 | 6.147 | — | bartowski |
| Q5_K_M | 15.73 GiB | 16,893,062,816 | 6.462 | — | mradermacher |
| Q5_K_M | 15.74 GiB | 16,904,121,824 | 6.466 | — | bartowski |
| Q5_K_L | 15.91 GiB | 17,085,101,024 | 6.535 | — | bartowski |
| Q6_K_L | 20.67 GiB | 22,193,345,504 | 8.489 | — | bartowski |
| Q6_K | 20.67 GiB | 22,193,345,504 | 8.489 | — | bartowski |
| Q6_K | 20.67 GiB | 22,193,345,696 | 8.489 | — | mradermacher |
| Q8_0 | 20.73 GiB | 22,261,912,736 | 8.515 | — | mradermacher |
| BF16 | 38.99 GiB | 41,860,888,288 | 16.012 | — | bartowski |
| IQ4_NL6 shards | 67.58 GiB | 72,559,573,792 | 27.754 | — | DavidAU |
| Q5_16 shards | 88.57 GiB | 95,097,440,032 | — | — | DavidAU |
| Q8_05 shards | 102.72 GiB | 110,296,079,200 | — | — | DavidAU |
KV cache by context
| Context | KV cache (f16)● | Flat formula | Overstated by | Full / windowed / recurrent |
|---|---|---|---|---|
| 4,096 | 0.11 GiB | 0.19 GiB | 1.68× | 12 / 12 / 0 |
| 8,192 | 0.21 GiB | 0.38 GiB | 1.83× | 12 / 12 / 0 |
| 16,384 | 0.39 GiB | 0.75 GiB | 1.91× | 12 / 12 / 0 |
| 32,768 | 0.77 GiB | 1.50 GiB | 1.95× | 12 / 12 / 0 |
| 65,536 | 1.52 GiB | 3.00 GiB | 1.98× | 12 / 12 / 0 |
| 131,072 | 3.02 GiB | 6.00 GiB | 1.99× | 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
Will it run on your card?
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
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.