About

GenSizer is a small set of free generator sizing calculators. We built it after a storm outage left friends guessing which appliances their portable unit could actually start. Here the math runs entirely in your browser; nothing you type is uploaded or stored.

Our calculators are reviewed by a working licensed electrician, Bob T., for sensible defaults and plain-English explanations. We are not a generator dealer and we do not sell units — we just want the number to be honest and free.