Mellum2.1 12B-A2.5B Thinking
Mellum2.1 12B-A2.5B Thinking loads in 8.1 GB at Q4_K_M and decodes at the speed of its 2.5B active path, comfortably from 12 GB of memory, Macs included, starting at the Mac Mini M6 16GB. Below is the memory math we ran for it, the smallest card that fits, and the fastest machine we track.
- Parameters
- 12.1B(2.5B active)
- Format
- Q4_K_M
- Min memory
- 16 GB
- Best for
- Agentic coding, Small machines
How much memory does Mellum2.1 12B-A2.5B Thinking need?
Mellum2.1 12B-A2.5B Thinking is a 12.1B mixture-of-experts model (2.5B active per token) built for agentic coding, small machines. The weights alone take 8.1 GB at Q4_K_M; add context and the OS, and it belongs in the 12 GB memory class. Every number below comes from the ModelFit engine: speeds are estimates, labeled est., because we do not benchmark hardware ourselves.
KV = fp16 estimate (q8_0 cache roughly halves it). "Comfortable" = weights + KV within the engine's tiered budget (~70-85% of memory).
Which machines run Mellum2.1 12B-A2.5B Thinking?
- Smallest GPU
- NVIDIA GeForce RTX 3060est. 98 tok/s · 12 GB VRAMtypical error 15%
- Fastest
- NVIDIA GeForce RTX 5090est. 344 tok/stypical error 15%
- Runs on a Mac?
- Mac Mini M6 16GBest. 53 tok/stypical error 10%
Verdicts come from the same engine that powers our fit checker: memory capacity first, bandwidth for speed. How we compute these numbers · What typical error means · Hugging Face model card
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Frequently asked questions
How much memory does Mellum2.1 12B-A2.5B Thinking need?
8.1 GB for the Q4_K_M weights, plus ~0.2 GB of KV-cache at 16k context, about 8.3 GB total. Comfortable from 12 GB of VRAM or unified memory.
Does Mellum2.1 12B-A2.5B Thinking run on a Mac?
Yes, from the Mac Mini M6 16GB (est. 53 tok/s, typical error 10%). Unified memory means the RAM budget is the only limit.
What is the smallest GPU for Mellum2.1 12B-A2.5B Thinking?
The NVIDIA GeForce RTX 3060 (12 GB VRAM) is the smallest tracked card that runs Mellum2.1 12B-A2.5B Thinking comfortably, est. 98 tok/s, typical error 15%.
Cite this page
ModelFit: Mellum2.1 12B-A2.5B Thinking, specs, memory math and hardware verdicts. https://modelfit.io/models/mellum2.1-12b/ (dataset updated 2026-10-24, CC BY 4.0).