Generator Sizing Calculator
Calculate the right generator size for your home backup power needs
About this calculator
The Generator Sizing Calculator helps homeowners determine the exact generator capacity needed to power essential appliances and systems during outages. By calculating your home's total power requirements, this tool ensures you choose a generator that's neither undersized (leaving you without adequate power) nor oversized (wasting money on unnecessary capacity). Proper generator sizing is crucial for reliable backup power, cost efficiency, and safe operation during emergencies.
How to use
Enter your home's essential appliances and their wattage requirements, including lights, refrigerator, heating/cooling systems, and electronics. The calculator will sum your total power needs and recommend the appropriate generator size in kilowatts, accounting for startup surge requirements and providing a safety margin for optimal performance.
Frequently asked questions
How do I find my appliance wattage requirements?
Check appliance nameplates, owner's manuals, or use online wattage guides. Most appliances list power consumption in watts or amps.
Should I include surge wattage in calculations?
Yes, motors and compressors need 2-3 times their running wattage to start. The calculator accounts for these surge requirements automatically.
What size generator do most homes need?
Most homes require 7,500-15,000 watts depending on size and essential appliances. Larger homes with electric heating may need 20,000+ watts.