Generator Size Calculator

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.

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Results

Total Generator Size Needed

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Generator KVA Rating

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Recommended Generator Size

Total Running Watts

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Power Distribution by Category

Frequently Asked Questions

How do I calculate the right generator size for my home?

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.

What's the difference between kW and kVA ratings?

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.

Do I need to power everything in my home during an outage?

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.

What appliances use the most power during startup?

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.

Should I get a larger generator than calculated?

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.

Can I run my central air conditioning on a generator?

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.

How does home size affect generator requirements?

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.

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