What Size Whole-House Generator Do You Need?

The first question most people ask about a standby generator is what size they need. It is the right question, and the answer is less about your home's square footage than you might think. It is about what you want to keep running when the power is out.

Sizing is about loads, not house size

A generator is sized in kilowatts, and the number you need depends on which circuits you want powered during an outage. Two homes the same size can need very different generators depending on whether they heat with gas or electric, how many AC units they run, and whether they want to power the whole panel or just the essentials.

Two approaches

• Whole-house coverage. The generator powers the entire electrical panel, so an outage is almost a non-event. This needs a larger unit, sized to your home's heating, cooling, and major appliances running together.
• Managed or essential circuits. The generator powers the circuits that matter most (furnace blower, refrigerator, sump pump, well, key outlets, often one AC) and a smart transfer switch sheds lower-priority loads as needed. This lets a smaller, more efficient unit cover what you actually care about.

What matters most in Kansas City

Two local loads drive a lot of KC sizing decisions. Summer air conditioning is a big one, since a central AC compressor draws a heavy surge when it starts. The other is the sump pump, because our storms and clay soil mean a power outage during heavy rain is exactly when a basement floods. Many homeowners here want the AC and the sump pump on the must-run list, and that shapes the size.

Get a real load assessment

A proper sizing looks at your panel, your heating and cooling, and your priority circuits, then matches a unit and a transfer switch to it. See our whole-house generator installation page, and we will connect you with a local installer who does the calculation rather than guessing.

Frequently asked questions