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Choosing a generator for your house

By the Plain Prepper editors. Updated 2026-10-14.

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Quick answer

List what you must keep running in an outage, add up their running watts, then add the largest starting watts. That total is the smallest generator that will do the job, so buy a little above it. Champion says most 2,000 square foot homes need 5,000 to 7,500 watts, and central air needs 10,000 or more. Whatever you buy, run it outdoors at least 20 feet from the house. Power the house through a transfer switch that a qualified electrician installs.

Decide what the generator has to power

A generator for your house is not about the house. It is about the handful of things you cannot do without for a day or a week. Most lists start with the refrigerator and freezer, a sump pump if you have one, the furnace fan in winter, some lights and phone charging, and any power-dependent medical device.

Food sets the clock. Ready.gov says a refrigerator keeps food cold for about four hours, and a full freezer holds its temperature for about 48 hours. Food that sits at 40 degrees or higher for two hours or more should be thrown out. So the fridge is usually the first thing on the list, and the sump pump is next if water is the risk.

Add up running and starting watts

Every appliance has a running wattage. Anything with a motor or compressor also needs a short burst of starting watts. Champion Power Equipment says starting watts are typically 1 to 2 times the running wattage and last only a fraction of a second. Its method is simple:

1. Add the running watts of everything you want on at the same time.
2. Find the single highest starting wattage on your list.
3. Add it to the running total. That is your peak need. Then pick a generator that beats it by a safe margin.

Here is an example using the top of Champion's published ranges:

Item	Running watts	Starting watts
Refrigerator	400	1,200
Sump pump, 1/2 HP	1,050	2,150
Furnace fan, 1/2 HP	800	1,600
10 LED bulbs at 15 W	150	none
Total	2,400	Highest: 2,150

Running total plus the highest starting load comes to 4,550 watts. That fits inside the 5,000 to 7,500 watt range Champion gives for most 2,000 square foot homes. Use your own appliance labels when you can, because real numbers vary.

Pick the type: portable, inverter or standby

Type	Fits	Trade-off
Conventional portable	Running several motor loads together: fridge, pump and furnace fan	Louder and heavier than an inverter
Inverter	Fridge, lights and electronics; quieter use	Check starting watts before counting on it for pumps
Home standby	Whole house, automatic start	Permanent install by licensed pros

Champion describes inverter generators as quieter and lighter than standard portables. It says they make clean, stable power for sensitive electronics, and adjust engine speed to the load for better fuel efficiency. It also says a 3,500 watt generator can run a modern refrigerator with room left for lights and small devices. That makes a mid-size inverter a good fit for a fridge-and-lights plan. For automatic whole-home backup, see our guide to a whole house generator.

Choose a fuel you can store

Gasoline is easy to find until a storm empties the pumps. Dual fuel generators run on gasoline or propane. Champion notes that propane keeps longer and burns cleaner, but typically delivers about 10% less wattage than gasoline. Size up for that if you plan to run on propane.

Store fuel only in a container made and labeled for it, outside living areas, as the NFPA tip sheet advises. Turn the generator off and let it cool before refueling. Never refuel it while it is hot.

Connect it to the house the right way

There are two safe ways to use a portable generator at home:

• Plug appliances in directly. Use the generator's outlets or a heavy-duty, outdoor-rated extension cord. NFPA says to check cords for cuts and tears, and make sure the plug has all three prongs, including the grounding pin.
• Feed chosen circuits through a transfer switch. NFPA says that if you must connect the generator to house wiring, a qualified electrician should install a properly rated transfer switch. It must follow the National Electrical Code and local codes.

Never plug a generator into a wall outlet to power the house. Our transfer switch guide covers the hardware.

Keep carbon monoxide out

The U.S. Consumer Product Safety Commission says an average of about 100 people die in the U.S. each year from carbon monoxide poisoning from portable generators. Its rules are short:

• Never run a generator in a home, garage, basement, crawlspace, shed or other enclosed space, even with doors or windows open.
• Run it outside, at least 20 feet from the house, and not on a porch or in a carport.
• Point the exhaust away from doors, windows and vents.
• Look for a carbon monoxide shut-off. CPSC says models certified to PGMA G300-2023 and UL 2201-2023 include CO safety technology, and UL 2201 models also have reduced CO emissions.

Ready.gov adds working carbon monoxide detectors on every level of the home.

What to look for when you buy

Questions people ask

What size generator do I need to run a house?

Add the running watts of what you need at once, then add the highest starting watts. Champion says most 2,000 square foot homes land between 5,000 and 7,500 watts, and central air pushes it to 10,000 or more.

How far from the house should a generator be?

CPSC, NFPA and Ready.gov all say at least 20 feet, outdoors, with the exhaust pointed away from doors, windows and vents.

How do you hook up a generator to the house?

Two safe ways: plug appliances into the generator with heavy-duty outdoor-rated cords, or have a qualified electrician install a properly rated transfer switch to the National Electrical Code. Never plug a generator into a wall outlet.

Is propane or gas better for a home generator?

Propane stores longer and burns cleaner, but Champion says it typically gives about 10% less wattage than gasoline. Dual fuel models let you use either.

Will a generator keep my fridge safe?

Yes, if it starts before food warms. Ready.gov says a fridge stays cold about four hours without power, and a full freezer about 48 hours.

Sources

• As Winter Storms Threaten Millions in the U.S., CPSC Issues Safety Tips to Help Families Prevent Carbon Monoxide Poisoning and Fires, U.S. Consumer Product Safety Commission
• CPSC Warns of Generator, Carbon Monoxide and Fire Hazards Ahead of Hurricane Season, U.S. Consumer Product Safety Commission
• Power Outages, Ready.gov
• Generator Safety tip sheet, National Fire Protection Association
• Generator Wattage Chart, Champion Power Equipment
• What Size Generator Do I Need?, Champion Power Equipment

Sources checked 2026-10-14.