Can I Run GPT-oss 120B on Apple M5 Max?

Written by Jakub Rusinowski · Last updated August 15, 2026

Yes. GPT-oss 120B needs 72.5 GB at Q4_K_M and the Apple M5 Max has 128 GB, leaving about 55.6 GB of headroom, at roughly 5 tok/s (estimated) with room for up to 128K of context.

The numbers

ModelGPT-oss 120B
Parameters120B
QuantizationQ4_K_M
VRAM needed72.5 GB
Apple M5 Max VRAM128 GB
VerdictRuns
Max context128K
Estimated speed~5 tok/s

What to do next

Nothing to change — run it at Q4_K_M. If you want more capability, check whether the next size up also fits.

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Running GPT-oss 120B on this card:

Apple MacBook Pro M5 Max
128 GB VRAM · 35 W board power
2026 prices are volatile — check the current listing.
Check price on Amazon

Buy vs. rent GPT-oss 120B
Buy the GPU
~$3,499
Apple M5 Max · MSRP
Rent by the hour
from $0.77/hr
A100 (80 GB) class

At 2 hrs/day, buying (~$3,499) beats renting at $0.77/hr after about 6.3 years.

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Vast.ai $0.77/hr · typical low · varies
Rent on Vast.ai →
RunPod $1.39/hr
Rent on RunPod →

Cloud rates verified 2026-07 — estimates, and marketplace prices vary. Buying price is GPU MSRP only, not a full PC.

Other GPT-OSS sizes on the Apple M5 Max

GPT-oss 120B on nearby hardware

All GPT-OSS sizes on the Apple M5 Max | VRAM calculator for GPT-oss 120B | Apple M5 Max GPU page | Check your hardware