Backup Power & Electrical Calculators
Size a generator for the things you need to keep running during an outage, and convert between watts, amps and volts for circuits and appliances.
- Generator Size CalculatorFind out what size generator you need for a power outage.
- Watts to Amps CalculatorConvert between watts and amps for any appliance or circuit.
Popular questions
Guides
Running watts vs starting watts
Motors in refrigerators, pumps and air conditioners draw a short surge when they start. A generator must cover the total running watts plus the largest single starting surge.
Safety first
Never run a portable generator indoors or in a garage, and connect it to home wiring only through a transfer switch or interlock installed by a licensed electrician.