Generator Wattage Calculator
Add up the running and starting watts of the appliances you want to power to find the minimum generator size you need.
How to Size a Generator
A generator must handle two loads: the continuous “running watts” of everything plugged in at once, plus the temporary “starting watts” surge that motor-driven appliances (like refrigerators or AC units) draw for a second or two when they switch on.
This calculator adds your total running watts to the starting-watt surge of your single largest appliance (since surges typically don’t overlap), then applies a safety margin to leave headroom and avoid running the generator at its absolute limit.
This is a general sizing estimate for planning purposes — always check your generator’s continuous and surge wattage ratings, and consult a qualified electrician for permanent backup power installations.