What size generator do you need for a 2,800 square foot house? The useful answer is not a single number - it is a range decided by your appliances, and the floor area is only a rough proxy. A 2,800 sq ft house with gas heat and a window AC needs 7,500-10,000 watts; the same floor area with an electric furnace, electric water heater, and 4-ton central AC needs 20,000-plus. Same house size, triple the generator. This page gives you the real numbers by configuration; the size calculator turns your actual appliance list into an exact figure.
The quick answers by heating type
| 2,800 sq ft house configuration | Realistic generator size |
|---|---|
| Gas heat, gas water heater, window AC | 7,500-10,000 W portable or small standby |
| Gas heat, gas water, 3-ton central AC | 14-18 kW standby |
| Gas heat, 3-4 ton AC, electric dryer | 18-22 kW standby |
| All-electric (heat, water, dryer, range) | 22-26 kW+ standby |
The pattern: heating fuel and AC tonnage move the number far more than square footage does. A 2,800 sq ft Texas house with a 4-ton compressor can out-demand a 4,000 sq ft New England house with gas everything.
Why square footage misleads
Generators are sized in watts, and watts are consumed by appliances, not by floors. The three demands that dominate every calculation are the electric motors with big starting surges - central AC compressors (2,000-5,000 W running, 3,500-8,000 W starting), well pumps, and furnace blowers - plus the electric resistance heaters (water heater, dryer, range) if you have them. Two houses of identical size differ enormously in all of these. That is why every sizing method worth using, ours included, starts with an appliance checklist, not a tape measure. Ours also handles the two subtleties manual math usually misses: the single largest motor's starting surge (motors do not all start at once) and altitude derating (3 percent output loss per 1,000 feet).
The one-minute method
Open the calculator, check off your appliances, set your elevation, and read the answer - running watts, starting watts, and the recommended size class with 20 percent margin built in. The wattage data behind it is Champion Power Equipment's published chart, the same data electricians use.
Once you have the number
Under ~10kW: the portable-plus-transfer-switch path covers it for $2,000-$3,500 - see portable whole house. Over 10kW: standby territory, where the best picks by home size and the cost guide take over. And if outages in your area are rare and brief, check your state's average before buying standby capability at all - a 2,800 sq ft house in Arizona (1.5 outage hours a year) has different needs than one in South Carolina (52).
FAQ
Will a 22kW generator run a 2,800 sq ft house?
Almost always yes, including a 4-ton central AC - unless the house is all-electric with every resistance heater running together. Verify with the calculator; 22kW is the right default for this size.
Is a 14kW generator enough for a 2,800 sq ft house?
With gas heat and a 3-ton AC, generally yes with managed loads. With electric water heating or a 4-ton unit, no.
How big of a generator do I need for a 2,800 square foot all-electric house?
Plan on 22-26 kW with a load-managed transfer switch; verify the starting-watt total of your compressor and resistance loads first.
Does square footage matter at all for generator sizing?
Only as a weak proxy for AC size and appliance count. Appliance list beats floor area every time.
