Select your home appliances — Central Air Conditioning, water heater type, well pump, sump pump, and more — and this Generator Size Calculator adds up your total running watts to give you the recommended generator size, plus the KVA rating you'll need to keep everything running during an outage.
Total Generator Size Needed
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Generator KVA Rating
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Recommended Generator Size
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Total Running Watts
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Calculate your total power needs by adding up the wattage of all appliances and systems you want to power during an outage. Include startup surge requirements for motors and compressors, then add 20-25% safety margin.
kW (kilowatts) measures real power consumption, while kVA (kilovolt-amperes) measures apparent power including reactive power. For home generators, kVA rating is typically 20-25% higher than kW rating.
No, you should prioritize essential systems like refrigeration, lighting, heating/cooling, and medical equipment. Non-essential items like electric dryers or multiple air conditioners can be temporarily turned off.
Air conditioners, well pumps, and electric motors require 2-3 times their running wattage during startup. Central AC units typically need the highest surge power, often 6000-8000 watts for a few seconds.
Yes, it's recommended to size your generator 20-25% larger than your calculated needs. This provides headroom for future additions and ensures efficient operation without overloading the unit.
Yes, but central AC requires significant power. A typical 3-ton central AC needs about 3500 watts running and up to 10,000 watts starting surge. Ensure your generator can handle this peak demand.
Larger homes typically need more lighting circuits, multiple HVAC zones, and more appliances. However, you don't need to power every room simultaneously - focus on essential areas and systems during outages.