Generator Size Calculator
Preparing for a power outage or need a generator for a job site? Select the appliances and devices you want to power, and this calculator totals the running and starting wattage to recommend the right generator size.
Generators must handle two loads: running watts (the continuous power draw of all appliances) and starting watts (the momentary surge when motor-driven appliances like refrigerators and AC units start up). Starting watts can be 1.5-3x the running watts for appliances with motors.
The calculator adds a 20% safety margin above the peak wattage to prevent overloading. Running a generator at full capacity constantly reduces its lifespan and efficiency. A comfortable operating range is 50-75% of the generator's rated capacity.
For sensitive electronics (computers, TVs), an inverter generator is recommended as it produces cleaner power with less harmonic distortion. Conventional generators are fine for resistive loads like heaters and lights.