About & methodology

SizingPlate answers one question — what size do I need — and shows its work. For generators, the sizing plate 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.

For portable power stations, we add a fourth question — energy. A station must deliver enough power (continuous watts and surge, same as a generator) and store enough energy (watt-hours) to cover your running load for the hours you need, including the roughly 15% lost converting battery power to household AC. We size capacity with a usable-charge margin so the battery isn't run flat.

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 fuel 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. Battery power stations produce no exhaust and are safe to run indoors. 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. For medical loads, keep redundant backup power and verify draw against the device's label.

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 or power station the math already chose.