About & methodology

SizingPlate answers one question — what size generator do I need — and shows its work. The sizing plate on every page computes three numbers: the sum of running watts for your selected loads, the worst-case peak (that sum plus the single largest start-up surge, because your biggest motor can start at any moment), and a buy target that adds 25% headroom so the generator never lives at its limit.

Wattage figures are typical values for common residential models, compiled from manufacturer specifications and standard load-planning references. Individual models vary — a 1990s refrigerator and a new ENERGY STAR unit can differ by 3x — so treat our figures as planning estimates and your appliance's nameplate as the truth.

Safety

Never run a generator indoors or in a garage, even with the door open — carbon monoxide kills quickly and silently. Keep units 20 feet from the house, away from windows. Hardwired connections (furnaces, well pumps, panels) require a transfer switch or interlock installed by a licensed electrician; backfeeding through a dryer outlet is illegal and endangers utility line workers.

How this site is funded

Product links may earn us a commission at no cost to you. Recommendations are computed from your wattage numbers first; the links simply point at the class of generator the math already chose.