What size generator does your home need?

In a Florida home, the air conditioner sets the size of the generator. Not because it uses the most power while running, but because of the surge it needs to start.

A compressor nameplate lists two numbers: running amps (RLA) and locked-rotor amps (LRA). On Goodman's GLXS3B spec sheet, the 3-ton unit lists 13.4 RLA and 83.3 LRA, and the 5-ton unit lists 23.9 RLA and 148 LRA. Multiply by 240 volts and you get this:

• 3-ton: about 3.2 kVA running, about 20.0 kVA at the instant it starts.
• 5-ton: about 5.7 kVA running, about 35.5 kVA to start.

Generac's sizing guidance says single-phase motors need three to five times their running power to start. Utility planning guides are more cautious still. DTE Energy's appliance worksheet lists a 3-ton central AC at 6,000 watts running with a starting factor of three. Your installer will read your actual nameplate, which is why a photo of it is the most useful thing to bring to the estimate.

Heat matters too. Generac's spec sheet says maximum output drops about 1% for each 10 F above 60 F. On a 95 F afternoon in The Villages, that is a few percent of capacity gone before the AC even starts.

Generators handle the surge in different ways. Cummins says its RS20A can start a 5-ton air conditioner under full pre-load. Generac and Kohler use load management to start big loads one at a time. Either way, the AC nameplate is where sizing begins.

If your home has two systems, a second zone doubles the starting problem unless the generator is told to start them in turn.

Photograph your AC nameplate before the estimate

After the air conditioner, list everything else you want running during an outage. Some loads are small but critical. Others are large but can wait.

Small and critical:

• An oxygen concentrator. Philips lists its EverFlo concentrator at an average of 350 watts. In Sumter County, October 2026 HHS emPOWER data counts 577 Medicare beneficiaries receiving oxygen services.
• The refrigerator and freezer. DTE's worksheet lists about 750 watts running with a starting factor of three, about 2,250 watts to start. The FDA says a closed refrigerator keeps food cold for about 4 hours and a full freezer about 48.
• Lights, fans, phone chargers, internet, the garage door. Small loads that make a long outage livable.

Large and flexible:

• The electric range and oven.
• The electric water heater.
• The clothes dryer.
• A pool or spa heater, if you have one.

These big resistive loads are where load management earns its keep. They do not need to run at the same moment as the AC. A system that holds the dryer until the compressor has started can run all of them on a smaller unit.

Write the list in two columns, must-run and nice-to-have. That single sheet of paper does more for an accurate quote than any square-footage rule. If someone in the home relies on medical equipment, put it at the top and read our medical backup power guide.

Bring a two-column must-run list to your estimate

Most Villages homes land in one of three approaches. None is right for everyone.

1. Essentials. A smaller generator runs a chosen set of circuits: refrigerator, medical equipment, lights, fans, internet and perhaps a small AC zone. Generac's air-cooled line includes 14 kW and 18 kW Guardian units. On propane at half load, Generac lists 1.81 gallons an hour for the 14 kW and 1.70 for the 18 kW. It costs less and sips fuel, but you choose which rooms stay comfortable.

2. Managed whole home. A mid-size or large generator powers the whole panel, with load management deciding what runs when. The service-rated switch packaged with Generac's 26 kW unit manages up to four air conditioner loads with no extra hardware, and Smart Management Modules can manage up to eight more large 240-volt loads. Kohler's load management handles up to six loads, and Cummins says its RS20A controls up to four. For most Villages homes this is the balance point.

3. Full whole home. A generator big enough to run everything at once without management. It needs the largest unit and burns the most fuel at full load. On propane from a 120-gallon above-ground tank, the size the ARC manuals cap, that matters a great deal.

Remember that ratings differ by fuel. Generac's 22 kW unit is rated 22 kW on propane and 19.5 kW on natural gas. The 26 kW is rated 26 kW on propane and 22.5 kW on natural gas. Size against the rating for the fuel you will actually use.

Your installer will match the approach to your panel, your loads and your budget. Our cost page shows how each choice moves the price.

Ask your installer to quote two sizes side by side

Load management is the quiet hero of generator sizing. It lets a generator act bigger than it is by never asking it to do everything at once.

Here is how it works on the major brands, from their own documents:

• Generac. Smart Management Modules (50-amp and 100-amp) manage large loads at startup and shed them to help the generator recover when overloaded. Generac says SMMs can in many cases reduce the overall size and cost of the system. An auxiliary contact kit can lock out a single large load that may not be needed.
• Kohler (Rehlko). An optional load shed kit or load management board manages up to six loads, with two relays for two independent AC loads and up to four power relay modules. Kohler says it is designed to comply with NEC Article 702.
• Cummins. The RS20A controls up to four loads, watches each one and restores only what the generator can run.

In practice, when the power fails the generator picks up lights, the refrigerator and the medical equipment first. Then it starts the air conditioner. Once the compressor is running, it allows the water heater or dryer. If the load climbs too high, the lowest-priority load drops off for a while and comes back when there is room.

You set the priorities with your installer. A typical order is medical equipment, refrigeration, the main AC, then everything else. Most people never notice the management working. They notice that the house stays cool and the generator never stalls.

The transfer switch guide explains how the switch and the modules work together.

Set your load priorities with an installer at the estimate

Most sizing advice stops at "will it start the AC?" For a household that wants to keep running for days or weeks, there is a second question: how long will the fuel last at the size you picked?

Fuel burn climbs with load. On Generac's 26 kW spec sheet, propane use is 2.06 gallons an hour at half load and 3.63 at full load. The district ARC manuals cap an above-ground propane tank at 120 gallons, and tanks are filled to about 80%, so a full tank of that size holds about 96 usable gallons. The math:

• 26 kW at half load: about 47 hours, roughly 1.9 days.
• 26 kW at full load: about 26 hours.
• 22 or 24 kW at half load (2.53 gallons an hour on Generac's sheet): about 38 hours.

A larger buried tank, which the manuals allow where setbacks and easements permit, gives the 26 kW about 4.0 days on 250 gallons and 8.1 days on 500 at half load. Many Villages lots cannot fit one. That is why, on propane, a generator that is sized well and managed well beats a bigger one running hard. Keeping the house near half load with load management can nearly double the time between refills compared with running flat out.

Natural gas changes the picture. There is no tank on site, so runtime is limited by the utility's supply and by maintenance. The same 26 kW unit uses about 188 cubic feet an hour at half load. Our fuel comparison covers the trade-offs honestly.

Runtime also means run hours on the engine. A three-week outage is about 494 run hours, which on a Generac in Florida heat means roughly five oil changes. Size for the outage you want to ride through, and plan the oil and fuel to match. See fuel runtime for more.

Ask your installer to show runtime at your expected load

For many Villages households the size floor is not comfort. It is health. The CDC says adults 65 and older are more prone to heat-related illness, and advises staying in air-conditioned buildings as much as possible in very hot weather rather than relying on a fan as the main cooling source.

Medical equipment adds a second floor. October 2026 HHS emPOWER data counts 2,478 Medicare beneficiaries in Sumter County who rely on power-dependent equipment, 577 of them on oxygen. A CDC study found that most oxygen concentrators run about 3 to 4 hours on battery at low settings, and less at higher flow.

Do not count on the utility to move you up the list in a hurricane. SECO Energy's Medically Necessary Service flags an account for crews only when emergency storm restoration is not in effect. During named-storm restoration, shelters, hospitals and government facilities come first. SECO suggests a backup generator, evacuation or a county shelter.

So the smallest system worth buying in that situation is one that can run, at the same time:

• the medical equipment, every hour of the outage,
• refrigeration for food and any refrigerated medicine,
• at least one cooled room, which means at least one AC system or zone,
• lights and phone charging.

From that floor, add what you can afford in comfort, then plan the fuel. Also register with the Florida Special Needs Registry if it applies. It does not guarantee a shelter space, and it asks people to plan to be self-sufficient for at least 72 hours.

The sizer on this site has presets for essentials and medical needs, and your answers travel with your estimate request.

Use the sizer, then book your free estimate