Standby Generator Sizing Chart by Home Size
What size standby generator your home needs, by square footage and coverage level, with what each kW band actually runs.
The fastest way to size a whole-home standby generator is by square footage and how much of the house you want online during an outage. This chart matches the four brands PES Supply stocks — Generac, Kohler, Cummins, and Briggs & Stratton — to the three coverage levels installers actually quote.
| Home size | Essentials only | Most of home | Whole home |
|---|---|---|---|
| Up to 1,500 sq ft | 7–10 kW | 13–16 kW | 16–20 kW |
| 1,500–2,500 sq ft | 7–10 kW | 16–20 kW | 20–24 kW |
| 2,500–3,500 sq ft | 10–13 kW | 20–24 kW | 24–26 kW |
| 3,500–5,000 sq ft | 13–16 kW | 24–26 kW | 26–36 kW |
| 5,000+ sq ft / dual HVAC | 16–20 kW | 26–36 kW | 36–60+ kW (liquid-cooled) |
Air-cooled standby generators top out at 26 kW. Above that you move to liquid-cooled units, which also suit small commercial sites.
| Generator | Covers | Watch out for |
|---|---|---|
| 7–10 kW | Fridge (700 W), furnace fan (800 W), sump pump (800 W), LED lights, phone & internet | No central air; pick 4–6 circuits on a load-shedding switch |
| 13–16 kW | Above plus microwave, TV, garage door, well pump (750–1,500 W) | Central AC only with load management |
| 16–20 kW | Above plus 2–3 ton central AC (3,500 W running) and electric water heater (4,500 W) | Range and dryer still need load shed |
| 22–26 kW | Whole home on a 200 A service, including range and dryer | All-electric homes with heat pumps may still exceed it |
| 26 kW+ liquid-cooled | Large homes, dual 4-ton AC, dual fuel ranges, EV charging (with load management) | Three-phase power needs a commercial unit |
Two rules do most of the work. First, generator kW should be roughly the sum of the loads you want simultaneous — most homes never run more than 40% of their service rating at once. Second, motors (AC compressors, well pumps) draw 2–5x their running watts at startup, so leave 25–30% headroom. Run the numbers in our standby generator sizing calculator, then match the transfer switch with the transfer switch sizing chart.
Is a bigger standby generator always better?
No. An oversized generator never loads past 30%, which causes carbon buildup and wet-stacking. Right-sizing to 70–80% expected load is better for the engine.
What size generator for a 2,000 sq ft house?
16–20 kW covers a typical 2,000 sq ft home including central air; 7–10 kW if you only want essentials.
Do standby generators work with solar?
Yes, with the right transfer switch and possibly a supply-side tap — see our solar backfeed breaker guide for the 120% rule math.
Buying a standby generator?
Generac, Kohler, Cummins, and Briggs & Stratton units in stock, 7 kW to 150 kW — contractor pricing and freight quotes from a real desk.
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