Can I run Tess-4.5-27B on a Mac with 256 GB?

Yes

Its published weights (55.6 GB) fit in the 192 GB a Mac with 256 GB can use, with room for ≈ 256K tokens of context.

Full analysis of Tess-4.5-27B Everything that runs on Mac with 256 GB Get the weights on Hugging Face

hf download migtissera/Tess-4.5-27B

Files and context on Mac with 256 GB

Each file of Tess-4.5-27B (and of GGUF versions the site has analyzed), and how much context fits next to it, with the context cache in 16-bit or 8-bit.

File	Size	On Mac with 256 GB	Context (16-bit)	Context (8-bit)
As published	55.6 GB	Fits	256K	256K
Q8_0migtissera/Tess-4.5-27B-GGUF	28.6 GB	Fits	256K	256K
Q6_Kmigtissera/Tess-4.5-27B-GGUF	22.1 GB	Fits	256K	256K
Q4_K_Mmigtissera/Tess-4.5-27B-GGUF	16.5 GB	Fits	256K	256K

Tess-4.5-27B on other hardware

Popular models that run on Mac with 256 GB

Assumes 75% of the Mac's memory is usable (macOS's default limit for the GPU; it can be raised) and at least 4K tokens of context for one conversation, with the context cache in 16-bit unless noted. Fits leaves at least 20% of that memory for context; Tight leaves less.