Can I run granite-4.1-3b on a Mac with 64 GB?

Yes

Its published weights (6.81 GB) fit in the 48.0 GB a Mac with 64 GB can use, with room for ≈ 128K tokens of context.

hf download ibm-granite/granite-4.1-3b

Files and context on Mac with 64 GB

Each file of granite-4.1-3b (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.

granite-4.1-3b on other hardware

Popular models that run on Mac with 64 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.