To determine the right size whole-house generator for your home, consider these key points:
General Generator Size Guidelines by Home Size
- Under 2,000 sq ft: A generator sized between 10,000 to 15,000 watts typically covers essential appliances like lights, refrigerator, freezer, furnace, and medical devices. Suitable for smaller homes or cottages
- 2,000 to 3,000 sq ft: A generator in the 15,000 to 22,000-watt range can power most household appliances including central air conditioning, sump pumps, and standard home systems
- 3,000 to 5,000 sq ft: Larger homes generally need a 22,000 to 32,000-watt generator to handle electric ovens, hot water heaters, multiple HVAC units, and other major appliances
- Over 5,000 sq ft: Very large homes with extra features like swimming pools, hot tubs, or EV chargers may require 36,000 watts or more , sometimes exceeding 50,000 watts
How to Calculate Your Exact Needs
- List all appliances and systems you want powered during an outage (lights, refrigerator, HVAC, sump pump, etc.).
- Add their running wattages (usually found on appliance labels or manuals).
- Add the highest starting wattage of any motor-driven appliance (like air conditioners or pumps) to the total.
- Multiply the total by 1.25 (or add 20-25%) to ensure the generator can handle startup surges and provide a safety margin
This calculation gives you the minimum generator capacity you should consider.
Additional Considerations
- Central air conditioners often consume the most power, so size your generator to handle their load if you want full HVAC backup
- Avoid undersizing your generator to prevent appliance malfunction or damage.
- Oversizing wastes fuel and increases costs, so balance size with your actual needs
- Consulting a certified electrician or using online sizing calculators from reputable suppliers can help refine your choice
In summary: Most typical homes need a whole-house generator between 15,000 and 30,000 watts , depending on size and appliances. Smaller homes can manage with 10,000 to 15,000 watts, while larger homes with more electrical demands require 22,000 watts or more. Always calculate your specific wattage needs and add a safety margin for reliable power during outages
