What are the hardware requirements for Mellum2.1 12B A2.5B Thinking?

Mellum2.1 12B A2.5B Thinking requires approximately 24.3 GB of VRAM and supports a context window of 128K tokens. Quantized variants may run on less VRAM; see the Quantized Models section on this page.

Who developed Mellum2.1 12B A2.5B Thinking and how large is it?

Mellum2.1 12B A2.5B Thinking is developed by JetBrains, a model with 12b parameters. The model is published as open weights on Hugging Face and indexed on LLM Explorer with full benchmark history.

Where can I download or evaluate Mellum2.1 12B A2.5B Thinking?

Mellum2.1 12B A2.5B Thinking is hosted on Hugging Face and linked from this page. LLM Explorer also lists quantized variants and similar alternatives if available.

Mellum2.1 12B A2.5B Thinking by JetBrains — VRAM 24.3GB, 128K context

Name: Mellum2.1 12B A2.5B Thinking
Author: JetBrains

Mellum2.1 12B A2.5B Thinking is an open-source language model by JetBrains. Features: 12b LLM, VRAM: 24.3GB, Context: 128K, License: apache-2.0, LLM Explorer Score: 0.37.

Arxiv:2605.31268 Base model:finetune:jetbrains/... Base model:jetbrains/mellum2-1... Conversational En Endpoints compatible Mellum Model-index Region:us Safetensors Sharded Tensorflow

Model Card on HF 🤗: https://huggingface.co/JetBrains/Mellum2.1-12B-A2.5B-Thinking

Mellum2.1 12B A2.5B Thinking Parameters and Internals

LLM Name	Mellum2.1 12B A2.5B Thinking
Repository 🤗	https://huggingface.co/JetBrains/Mellum2.1-12B-A2.5B-Thinking
Base Model(s)	JetBrains/Mellum2-12B-A2.5B-Base JetBrains/Mellum2-12B-A2.5B-Base
Model Size	12b
Required VRAM	24.3 GB
Updated	2026-10-11
Maintainer	JetBrains
Model Type	mellum
Model Files	5.0 GB: 1-of-5 5.0 GB: 2-of-5 5.0 GB: 3-of-5 5.0 GB: 4-of-5 4.3 GB: 5-of-5
Supported Languages	en
Model Architecture	MellumForCausalLM
License	apache-2.0
Context Length	131072
Model Max Length	131072
Transformers Version	5.8.1
Tokenizer Class	PreTrainedTokenizerFast
Padding Token	<\|endoftext\|>
Vocabulary Size	98304

Rank the Mellum2.1 12B A2.5B Thinking capabilities

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Instruction Following and Task Automation
Factuality and Completeness of Knowledge
Censorship and Alignment
Data Analysis and Insight Generation
Text Generation
Text Summarization and Feature Extraction
Code Generation
Multi-Language Support and Translation

Best Alternatives to Mellum2.1 12B A2.5B Thinking

Best Alternatives	Context / RAM	Downloads	Likes
Mellum2 12B A2.5B Thinking	128K / 24.3 GB	6221	327
Mellum2 12B A2.5B Base	128K / 24.3 GB	16753	23
Mellum2 12B A2.5B Instruct	128K / 24.3 GB	4498	82
...llum2 12B A2.5B Thinking Mxfp4	128K / 6.4 GB	301	1
...llum2 12B A2.5B Instruct Mxfp4	128K / 6.4 GB	166	1
...12B A2.5B Thinking Abliterated	128K / 24.3 GB	76	5
...ellum2 12B A2.5B Thinking 4bit	128K / 6.8 GB	126	1
...m2 12B A2.5B Thinking Mlx 4bit	128K / 7.3 GB	521	5
...ellum2 12B A2.5B Instruct 4bit	128K / 6.8 GB	14	1