What Size Generator Do You Need for Your Home
By LumoWatt Editorial Team · Published 2026-08-02
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Find installers near you →Home size is a starting point, not the answer
Square footage gives a rough sense of scale, but generator sizing is really about electrical load: how many circuits, how much air conditioning, whether you have major motor-driven equipment like a well pump, not square footage directly. Two similarly sized homes can need very different generator sizes depending on what is actually plugged into the panel.
Quick reference: home size, typical capacity, and unit cost
| Home size | Typical capacity | Approximate unit cost | What it typically covers |
|---|---|---|---|
| Under 1,500 sq ft | 10 to 14 kW | $2,500 to $4,500 | Refrigerator, well pump, lights, one AC zone |
| 1,500 to 3,000 sq ft | 16 to 20 kW | $4,500 to $7,000 | Most circuits, larger AC system |
| 3,000 to 5,000 sq ft | 22 to 26 kW | $6,500 to $10,000 | Whole home, multiple HVAC zones |
| Over 5,000 sq ft | 28 to 38 kW+ | $10,000 to $15,000+ | Whole home plus high-draw appliances |
Unit cost is for the generator alone, before installation labor (typically $3,000 to $5,000), transfer switch, or permit fees. See the whole house generator cost guide for all-in price breakdowns, and the cost by city guide for regional labor rate variation.
Why a real load calculation still matters
These tiers are a reasonable starting point, not a substitute for the load calculation a licensed installer will do based on your actual electrical panel. A home with a pool, an EV charger, or multiple HVAC zones can need more capacity than its size alone would suggest.
Use the sizing calculator for an estimate based on what is actually in your home, then get 2 to 3 quotes from verified local installers who will do a real load calculation. See the full sizing guide for more detail on each tier.