Break-even index / Mac M-series / GPT-5.4 / North Carolina
Will a Mac (M-series, unified memory) beat GPT-5.4 in North Carolina?
Break-even lands around month 23. Real, but slow — a hybrid setup (local for the routine work, cloud for the peaks) usually beats going all-in.
How to read it: OWN — the rig pays for itself inside 18 months. HYBRID — break-even lands between 18 and 36 months; real, but slow. RENT — it never pays off before the hardware is due for replacement. Every formula and threshold is public on the methodology page.
The numbers
| Build cost (Mac (M-series, unified memory)) | $3,000 ($2,000–$4,000) |
|---|---|
| Hardware amortized (3 yr) | $83.33/mo |
| Electricity in North Carolina ($0.135/kWh) | $1.30/mo (9.6 kWh) |
| Local total cost of ownership | $84.63/mo |
| GPT-5.4 at the same usage | $131/mo |
| Break-even | about 23 months |
Assumes the "coding assistant" preset: ~15M tokens/month, 3 h/day active, 5 h/day idle. GPT-5.4 priced at $2.5/M in, $15/M out (verified 2026-07-05). Rig ceiling: Up to 70B via unified memory (slower prompt processing). Jargon: VRAM is the GPU memory that decides which models fit; Q4 is 4-bit quantization — a smaller, faster copy of a model with a slight quality cost.
See your verdict — then tweak every number →