To determine the right size generator for your house, you should calculate the total wattage of the appliances and devices you want to power during an outage. List all essential items, note their start-up wattages, and add them together.
Here are some typical wattage requirements for common appliances:
Refrigerator: 600 watts
Large dehumidifier: 700 watts
Large window air conditioner: 1,400 watts
Water heater: 3,000 to 4,500 watts
Electric furnace: 5,000 to 25,000 watts
A 7,500-watt generator might be sufficient for essentials like a refrigerator, freezer, well pump, and lighting circuits. However, for high-demand items like a water heater or furnace, a whole-home generator is a better choice. A portable generator may be enough if you only need to power a few critical items.
While home square footage can offer a rough estimate, it is not always a reliable indicator. For reference, here are some typical generator sizes based on square footage:
1,000 sq ft: 6–9 kW
1,500 sq ft: 7–10 kW
2,000 sq ft: 10–14 kW
2,500 sq ft: 12–16 kW
3,000 sq ft: 16–20 kW+
For the most accurate sizing, consult a professional who can calculate your home's peak and average power consumption and recommend the optimal generator.
