alt.freeweights.text / Mellum2-12B-A2.5B-Thinking-GGUF
From: bartowski <huggingface.co/bartowski>Newsgroups: alt.freeweights.textSubject:

Mellum2-12B-A2.5B-Thinking-GGUF

Date: 2026-11-15Commit: e10a3d1Signed: 2DC28CC7B26A283B ✓

Text generation model. Gguf weights, 208 GB in all. Published by bartowski under Apache-2.0.

text208GBMellum2-12B-A2.5B-Thinking-GGUFggufpermissive
FactsParamsnot statedSize208 GBFormatsggufTasktext generationLicenseApache-2.0From sourcepermissive
$ fw get bartowski/Mellum2-12B-A2.5B-Thinking-GGUF
# manifest sha256 d815ebb8321d… · 208 GB · 29 files
$ fw verify ./Mellum2-12B-A2.5B-Thinking-GGUF bartowski/Mellum2-12B-A2.5B-Thinking-GGUF
From sourceHosted (signed)bartowski/Mellum2-12B-A2.5B-Thinking-GGUFLast check: 2026-11-15 05:01 UTC

Get help: custom fine-tune or private deploy. We review your setup before we quote.

Quantized of Mellum2-12B-A2.5B-Thinking.

Works with

Convert with

Overview

Size
208 GB
Weights
41.0 MB (smallest of 27 GGUF variants)
Parameters
not stated
Formats
gguf
Task
text generation
License
Apache-2.0 (permissive)
Files
29, each with a sha256
Publisher
bartowski
Added
2026-11-15
Section
alt.freeweights.text
Lineage

Original release from the publisher.

Base model: JetBrains/Mellum2-12B-A2.5B-Thinking

Where these bytes come from
Publisher at the pinned commit→You

Sources are tried in order. A file counts only when its size and sha256 match the manifest. Sources are checked when you ask for them, not on a timer.

Sources
BadgeHostLast checkResult
From sourcehuggingface.co2026-11-15 05:01 UTCpassed

Model card

From the publisher at commit e10a3d1. Shown as plain text with links; images open at the publisher.

Llamacpp imatrix Quantizations of Mellum2-12B-A2.5B-Thinking by JetBrains#

Using llama.cpp release b9590 for quantization.

Original model: https://huggingface.co/JetBrains/Mellum2-12B-A2.5B-Thinking

All quants made using imatrix option with dataset from here

Run them in your choice of tools:

Note: if it's a newly supported model, you may need to wait for an update from the developers.

Prompt format#

<|im_start|>system
{system_prompt}<|im_end|>
<|im_start|>user
{prompt}<|im_end|>
<|im_start|>assistant

Download a file (not the whole branch) from below:#

FilenameQuant typeFile SizeSplitDescription
Mellum2-12B-A2.5B-Thinking-bf16.ggufbf1624.31GBfalseFull BF16 weights.
Mellum2-12B-A2.5B-Thinking-Q8_0.ggufQ8_012.93GBfalseExtremely high quality, generally unneeded but max available quant.
Mellum2-12B-A2.5B-Thinking-Q6_K_L.ggufQ6_K_L11.10GBfalseUses Q8_0 for embed and output weights. Very high quality, near perfect, recommended.
Mellum2-12B-A2.5B-Thinking-Q6_K.ggufQ6_K10.99GBfalseVery high quality, near perfect, recommended.
Mellum2-12B-A2.5B-Thinking-Q5_K_L.ggufQ5_K_L9.43GBfalseUses Q8_0 for embed and output weights. High quality, recommended.
Mellum2-12B-A2.5B-Thinking-Q5_K_M.ggufQ5_K_M9.29GBfalseHigh quality, recommended.
Mellum2-12B-A2.5B-Thinking-Q5_K_S.ggufQ5_K_S8.67GBfalseHigh quality, recommended.
Mellum2-12B-A2.5B-Thinking-Q4_K_L.ggufQ4_K_L8.34GBfalseUses Q8_0 for embed and output weights. Good quality, recommended.
Mellum2-12B-A2.5B-Thinking-Q4_K_M.ggufQ4_K_M8.17GBfalseGood quality, default size for most use cases, recommended.
Mellum2-12B-A2.5B-Thinking-Q4_1.ggufQ4_17.71GBfalseLegacy format, similar performance to Q4_K_S but with improved tokens/watt on Apple silicon.
Mellum2-12B-A2.5B-Thinking-Q4_K_S.ggufQ4_K_S7.56GBfalseSlightly lower quality with more space savings, recommended.
Mellum2-12B-A2.5B-Thinking-IQ4_NL.ggufIQ4_NL7.01GBfalseSimilar to IQ4_XS, but slightly larger. Offers online repacking for ARM CPU inference.
Mellum2-12B-A2.5B-Thinking-Q4_0.ggufQ4_07.00GBfalseLegacy format, offers online repacking for ARM and AVX CPU inference.
Mellum2-12B-A2.5B-Thinking-IQ4_XS.ggufIQ4_XS6.77GBfalseDecent quality, smaller than Q4_K_S with similar performance, recommended.
Mellum2-12B-A2.5B-Thinking-Q3_K_XL.ggufQ3_K_XL6.46GBfalseUses Q8_0 for embed and output weights. Lower quality but usable, good for low RAM availability.
Mellum2-12B-A2.5B-Thinking-IQ3_M.ggufIQ3_M6.33GBfalseMedium-low quality, new method with decent performance comparable to Q3_K_M.
Mellum2-12B-A2.5B-Thinking-Q3_K_L.ggufQ3_K_L6.26GBfalseLower quality but usable, good for low RAM availability.
Mellum2-12B-A2.5B-Thinking-Q3_K_M.ggufQ3_K_M6.18GBfalseLow quality.
Mellum2-12B-A2.5B-Thinking-IQ3_XS.ggufIQ3_XS6.18GBfalseLower quality, new method with decent performance, slightly better than Q3_K_S.
Mellum2-12B-A2.5B-Thinking-Q3_K_S.ggufQ3_K_S5.95GBfalseLow quality, not recommended.
Mellum2-12B-A2.5B-Thinking-IQ3_XXS.ggufIQ3_XXS5.80GBfalseLower quality, new method with decent performance, comparable to Q3 quants.
Mellum2-12B-A2.5B-Thinking-Q2_K_L.ggufQ2_K_L5.38GBfalseUses Q8_0 for embed and output weights. Very low quality but surprisingly usable.
Mellum2-12B-A2.5B-Thinking-Q2_K.ggufQ2_K5.16GBfalseVery low quality but surprisingly usable.
Mellum2-12B-A2.5B-Thinking-IQ2_M.ggufIQ2_M5.10GBfalseRelatively low quality, uses SOTA techniques to be surprisingly usable.
Mellum2-12B-A2.5B-Thinking-IQ2_S.ggufIQ2_S4.87GBfalseLow quality, uses SOTA techniques to be usable.
Mellum2-12B-A2.5B-Thinking-IQ2_XS.ggufIQ2_XS4.81GBfalseLow quality, uses SOTA techniques to be usable.

Embed/output weights#

Some of these quants (Q3_K_XL, Q4_K_L etc) are the standard quantization method with the embeddings and output weights quantized to Q8_0 instead of what they would normally default to.

Downloading using huggingface-cli#

Click to view download instructions

First, make sure you have hugginface-cli installed:

pip install -U "huggingface_hub[cli]"

Then, you can target the specific file you want:

huggingface-cli download bartowski/Mellum2-12B-A2.5B-Thinking-GGUF --include "Mellum2-12B-A2.5B-Thinking-Q4_K_M.gguf" --local-dir ./

If the model is bigger than 50GB, it will have been split into multiple files. In order to download them all to a local folder, run:

huggingface-cli download bartowski/Mellum2-12B-A2.5B-Thinking-GGUF --include "Mellum2-12B-A2.5B-Thinking-Q8_0/*" --local-dir ./

You can either specify a new local-dir (Mellum2-12B-A2.5B-Thinking-Q8_0) or download them all in place (./)

ARM/AVX information#

Previously, you would download Q4_0_4_4/4_8/8_8, and these would have their weights interleaved in memory in order to improve performance on ARM and AVX machines by loading up more data in one pass.

Now, however, there is something called "online repacking" for weights. details in this PR. If you use Q4_0 and your hardware would benefit from repacking weights, it will do it automatically on the fly.

As of llama.cpp build b4282 you will not be able to run the Q4_0_X_X files and will instead need to use Q4_0.

Additionally, if you want to get slightly better quality for , you can use IQ4_NL thanks to this PR which will also repack the weights for ARM, though only the 4_4 for now. The loading time may be slower but it will result in an overall speed incrase.

Click to view Q4_0_X_X information (deprecated

I'm keeping this section to show the potential theoretical uplift in performance from using the Q4_0 with online repacking.

Click to view benchmarks on an AVX2 system (EPYC7702)

modelsizeparamsbackendthreadstestt/s% (vs Q4_0)
qwen2 3B Q4_01.70 GiB3.09 BCPU64pp512204.03 ± 1.03100%
qwen2 3B Q4_01.70 GiB3.09 BCPU64pp1024282.92 ± 0.19100%
qwen2 3B Q4_01.70 GiB3.09 BCPU64pp2048259.49 ± 0.44100%
qwen2 3B Q4_01.70 GiB3.09 BCPU64tg12839.12 ± 0.27100%
qwen2 3B Q4_01.70 GiB3.09 BCPU64tg25639.31 ± 0.69100%
qwen2 3B Q4_01.70 GiB3.09 BCPU64tg51240.52 ± 0.03100%
qwen2 3B Q4_K_M1.79 GiB3.09 BCPU64pp512301.02 ± 1.74147%
qwen2 3B Q4_K_M1.79 GiB3.09 BCPU64pp1024287.23 ± 0.20101%
qwen2 3B Q4_K_M1.79 GiB3.09 BCPU64pp2048262.77 ± 1.81101%
qwen2 3B Q4_K_M1.79 GiB3.09 BCPU64tg12818.80 ± 0.9948%
qwen2 3B Q4_K_M1.79 GiB3.09 BCPU64tg25624.46 ± 3.0483%
qwen2 3B Q4_K_M1.79 GiB3.09 BCPU64tg51236.32 ± 3.5990%
qwen2 3B Q4_0_8_81.69 GiB3.09 BCPU64pp512271.71 ± 3.53133%
qwen2 3B Q4_0_8_81.69 GiB3.09 BCPU64pp1024279.86 ± 45.63100%
qwen2 3B Q4_0_8_81.69 GiB3.09 BCPU64pp2048320.77 ± 5.00124%
qwen2 3B Q4_0_8_81.69 GiB3.09 BCPU64tg12843.51 ± 0.05111%
qwen2 3B Q4_0_8_81.69 GiB3.09 BCPU64tg25643.35 ± 0.09110%
qwen2 3B Q4_0_8_81.69 GiB3.09 BCPU64tg51242.60 ± 0.31105%

Q4_0_8_8 offers a nice bump to prompt processing and a small bump to text generation

Which file should I choose?#

Click here for details

A great write up with charts showing various performances is provided by Artefact2 here

The first thing to figure out is how big a model you can run. To do this, you'll need to figure out how much RAM and/or VRAM you have.

If you want your model running as FAST as possible, you'll want to fit the whole thing on your GPU's VRAM. Aim for a quant with a file size 1-2GB smaller than your GPU's total VRAM.

If you want the absolute maximum quality, add both your system RAM and your GPU's VRAM together, then similarly grab a quant with a file size 1-2GB Smaller than that total.

Next, you'll need to decide if you want to use an 'I-quant' or a 'K-quant'.

If you don't want to think too much, grab one of the K-quants. These are in format 'QX_K_X', like Q5_K_M.

If you want to get more into the weeds, you can check out this extremely useful feature chart:

llama.cpp feature matrix

But basically, if you're aiming for below Q4, and you're running cuBLAS (Nvidia) or rocBLAS (AMD), you should look towards the I-quants. These are in format IQX_X, like IQ3_M. These are newer and offer better performance for their size.

These I-quants can also be used on CPU, but will be slower than their K-quant equivalent, so speed vs performance is a tradeoff you'll have to decide.

Credits#

Thank you kalomaze and Dampf for assistance in creating the imatrix calibration dataset.

Thank you ZeroWw for the inspiration to experiment with embed/output.

Thank you to LM Studio for sponsoring my work.

Want to support my work? Visit my ko-fi page here: https://ko-fi.com/bartowski

Files

29 files · 208 GBWeights 41.0 MB (smallest of 27 GGUF variants). Sizes and sha256 from the signed manifest.
Show all 29 files with their sha256
FileSizesha256
.gitattributes3.53 KB30da290c487497ed52f2e9ff5ee41a8caa900f8c4af5d127597c612a6cf8d137
Mellum2-12B-A2.5B-Thinking-IQ2_M.gguf5.10 GBfbbac126bd38c42f2f0ff84350ac38ecde6778e7fc70cf1f847da948e82be539
Mellum2-12B-A2.5B-Thinking-IQ2_S.gguf4.87 GBb20065a5a214278a3cfb74a49d1ad30129bd87f700161715b19b5c5d329aba7b
Mellum2-12B-A2.5B-Thinking-IQ2_XS.gguf4.81 GB903ba23005e6839df6bad451af1f81a896373f2239f27bef9565a4fc035fb84b
Mellum2-12B-A2.5B-Thinking-IQ3_M.gguf6.33 GB6c85122aedea1efa6d10d5202622d4d343d48206d2e8abf8e7502a5da7dcd2c5
Mellum2-12B-A2.5B-Thinking-IQ3_XS.gguf6.18 GB1b5352ba7876ac6d17d54175685e5eab29f579d371e3a2c0b22996efc7a7e038
Mellum2-12B-A2.5B-Thinking-IQ3_XXS.gguf5.80 GBbc51ab2656caa55580bb68784e9eaad3d87915ef1d911eec3f6d7392648e8eb1
Mellum2-12B-A2.5B-Thinking-IQ4_NL.gguf7.01 GB5e63386f93f0d7fa8717b7c848cbc7f16a7320e247d60714d8f741fbf26cdcfc
Mellum2-12B-A2.5B-Thinking-IQ4_XS.gguf6.77 GBee4babb04800682dea267a5e6adbc0cc11f2f3b0e34305de592788a698725ba7
Mellum2-12B-A2.5B-Thinking-Q2_K.gguf5.16 GB69bd9d535cc2ce71c7700c992e7b017e861fed9f6c772303dc9d4bfd374a4bff
Mellum2-12B-A2.5B-Thinking-Q2_K_L.gguf5.38 GB54eabff2a72139035cb3f6803a5023bceb93d0db3593f903cbdc16176e3511f1
Mellum2-12B-A2.5B-Thinking-Q3_K_L.gguf6.26 GB4d98f72d4aad041dca3a96aecab7734793baf5c1a6a411178d7ef1adc48ce58d
Mellum2-12B-A2.5B-Thinking-Q3_K_M.gguf6.18 GBe3645f149150125f6c6a7e505e8a2548525113b74c8b8616db09e61919697c36
Mellum2-12B-A2.5B-Thinking-Q3_K_S.gguf5.95 GB4f564f891beb74a94003af1715f23113f904fa2e727a493f85e3455b533d16ee
Mellum2-12B-A2.5B-Thinking-Q3_K_XL.gguf6.46 GB81cb3579e0736869250c8c9716d2ec12bcbf7565771737d2efcf13c38fda1846
Mellum2-12B-A2.5B-Thinking-Q4_0.gguf7.00 GBce6d8fbc012e787109866b76b7a50a77216c69bdb72fe8dcdb5db8174ad71dd2
Mellum2-12B-A2.5B-Thinking-Q4_1.gguf7.71 GBbced634908d4b1e2e645bfa373f65c06035c3556a90cfdccf41b82a9cd62aa22
Mellum2-12B-A2.5B-Thinking-Q4_K_L.gguf8.34 GBa72c9b6ee254518d7894b934816bc8e2fe07a24223cfee52e9929cea7fca77c6
Mellum2-12B-A2.5B-Thinking-Q4_K_M.gguf8.17 GB6f04f80d7ffd51425ac159af6f832bfb52241744fea195957d7dfaaa371a5f9a
Mellum2-12B-A2.5B-Thinking-Q4_K_S.gguf7.56 GBf6487694cc5946c1daa84c6869ad4df096cd5b56fa27d6f11afa2891791e397c
Mellum2-12B-A2.5B-Thinking-Q5_K_L.gguf9.43 GB37622e26f7b7c47ff86398866425ec75e5fe3c701da707966317ab278cf425fe
Mellum2-12B-A2.5B-Thinking-Q5_K_M.gguf9.29 GB09b7e20ea2ced6dcff174d6b44a94d6c175f6674b74025cc243c517c38f6d3d0
Mellum2-12B-A2.5B-Thinking-Q5_K_S.gguf8.67 GBc020f52f937c6d77cc56763cce5de4c2e087e4b0d16689fde7c0a23f5e309cec
Mellum2-12B-A2.5B-Thinking-Q6_K.gguf11.0 GB60e6dc1e3f683f7c589711371d2b41cb324d1138dd9ee962182e38eb59a85dca
Mellum2-12B-A2.5B-Thinking-Q6_K_L.gguf11.1 GB02efc81587c90f69f85672d5c1de06c1dd324b49c4f4099f8f6808c3381378ec
Mellum2-12B-A2.5B-Thinking-Q8_0.gguf12.9 GB377450dc07c16296798f7cc5d58f9a88de3023ecf36e2167465589143d3d9e3a
Mellum2-12B-A2.5B-Thinking-bf16.gguf24.3 GBe8695afc82fd5acb24109a665db7ff61020b7a09da5b9cf18b7de733da7a4f6c
Mellum2-12B-A2.5B-Thinking-imatrix.gguf41.0 MB0b627b544e5dbc9bb3e612a07b397ca562a2d31fd14990eddc6244fa2b61ba48
README.md17.5 KB24a18de1699474b73d155d75aa3c778995639d7f376d0902e43706cdddff9fa6
VersionsEach time the pinned upstream commit or file list changed in this repo. Newest first.
Upstream commitDateContents
e10a3d18c7 pinned now2026-11-15 05:01 UTC29 files · 208 GB

Use it

$ fw get bartowski/Mellum2-12B-A2.5B-Thinking-GGUF
# manifest sha256 d815ebb8321d… · 208 GB · 29 files
$ fw verify ./Mellum2-12B-A2.5B-Thinking-GGUF bartowski/Mellum2-12B-A2.5B-Thinking-GGUF
fw.pyChecks the signature and every sha256, tries each source in order, resumes.
$ python3 fw.py get https://freeweights.allternit.com/manifests/bartowski/Mellum2-12B-A2.5B-Thinking-GGUF.json --dir ./Mellum2-12B-A2.5B-Thinking-GGUF $ python3 fw.py verify ./Mellum2-12B-A2.5B-Thinking-GGUF ./bartowski__Mellum2-12B-A2.5B-Thinking-GGUF.json
hfThe Hugging Face CLI with one setting. Same repo id.
$ HF_ENDPOINT=https://freeweights.allternit.com hf download bartowski/Mellum2-12B-A2.5B-Thinking-GGUF --revision e10a3d18c7a65d9e06a1ef9c228082fbbc798182 --local-dir ./Mellum2-12B-A2.5B-Thinking-GGUF
llama.cppDownload one GGUF variant (Mellum2-12B-A2.5B-Thinking-imatrix, 41.0 MB), then serve it.
$ HF_ENDPOINT=https://freeweights.allternit.com hf download bartowski/Mellum2-12B-A2.5B-Thinking-GGUF --include "Mellum2-12B-A2.5B-Thinking-imatrix*" --local-dir ./Mellum2-12B-A2.5B-Thinking-GGUF $ llama-server -m ./Mellum2-12B-A2.5B-Thinking-GGUF/Mellum2-12B-A2.5B-Thinking-imatrix.gguf
OllamaMake an Ollama model from the downloaded file.
$ printf 'FROM ./Mellum2-12B-A2.5B-Thinking-GGUF/Mellum2-12B-A2.5B-Thinking-imatrix.gguf\n' > Modelfile $ ollama create mellum2-12b-a2.5b-thinking-gguf -f Modelfile

License

Name
Apache License 2.0
Id
Apache-2.0
Class
Permissive
Redistribution
yes
Listing
Hosted (signed)
Decided
License as declared by the publisher. No person read it. 2026-11-15
Text in
README.md
Text sha256
24a18de1699474b73d155d75aa3c778995639d7f376d0902e43706cdddff9fa6
Terms gate
No extra terms beyond the license.

Read the license text

Licenses are checked against the license table. A custom license passes only after a person reads it.

Provenance

From: bartowski <huggingface.co/bartowski>Newsgroups: alt.freeweights.textSubject: Mellum2-12B-A2.5B-Thinking-GGUFDate: 2026-11-15Commit: e10a3d1Signed: 2DC28CC7B26A283B ✓
Upstream
bartowski/Mellum2-12B-A2.5B-Thinking-GGUF
Pinned commit
e10a3d18c7a65d9e06a1ef9c228082fbbc798182
Manifest
Mellum2-12B-A2.5B-Thinking-GGUF.json · .minisig
Manifest sha256
d815ebb8321dadbdc70dcd4619c39d2178b4aa60f4889a3431081a51ea98e206
Signature
minisign, Ed25519, key 2DC28CC7B26A283B
Created
2026-11-15 05:01 UTC
Generator
freeweights-manifest/0.1.0
Takedowns
None.

How to verify

$ curl -O https://freeweights.allternit.com/manifests/bartowski/Mellum2-12B-A2.5B-Thinking-GGUF.json $ curl -O https://freeweights.allternit.com/manifests/bartowski/Mellum2-12B-A2.5B-Thinking-GGUF.json.minisig $ minisign -Vm Mellum2-12B-A2.5B-Thinking-GGUF.json -P RWQ7KGqyx4zCLXtUFOqvfv8L3g+8fpKJ1FsuxPyOYMF+4KufbUxKq1Oq $ shasum -a 256 <file> # compare with the Files tab

A manifest whose signature fails must be rejected. A file whose size or sha256 does not match must be discarded. Verify a download

Model tree

Parent

JetBrains/Mellum2-12B-A2.5B-Thinking · this model is a quantization of it

No model in the catalog names this one as its parent.

Get it
Download
$ HF_ENDPOINT=https://freeweights.allternit.com hf download bartowski/Mellum2-12B-A2.5B-Thinking-GGUF
Open in Freeweights Studio

Pull, verify and run it in the Allternit app on Desktop, web or phone.

Signed manifest
minisign, key 2DC28CC7B26A283B. Mellum2-12B-A2.5B-Thinking-GGUF.json. Provenance. Takedown history: none.
From: laion <huggingface.co/laion>Subject: a2-rl-e2egit_large-50-32B
From: laion <huggingface.co/laion>Subject: a3-rl-DCAgent_exp_rpt_e2egit-large-15-8B
From: laion <huggingface.co/laion>Subject: a3-rl-DCAgent_exp_rpt_e2egit-v2-10-8B
From: laion <huggingface.co/laion>Subject: a3-rl-DCAgent_exp_rpt_pymethods2test-large-80-8B
From: laion <huggingface.co/laion>Subject: a3-rl-DCAgent_exp_rpt_unitsyn-python-large-10-8B
From: laion <huggingface.co/laion>Subject: a3-rl-DCAgent_mix_h2_language_proportional-65-8B