Quick answer: a generator for house power outage use falls into one of two camps. A portable unit ($600 - $2,000) runs a fridge, some lights, and a few outlets through a transfer switch. A standby unit ($5,000 - $15,000 installed) starts itself and runs most of the house. Which one is right depends on what you refuse to live without during an outage, not on brand names.
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Every winter the question lands in our inbox the same way: the power went out last week, and now the family wants a generator for the next time. The good news is that the choice is simpler than the marketing makes it look. You only need three answers: what has to run, for how many days, and who is going to start it at 2 a.m. Everything else, including wattage and fuel type, follows from those answers.
What a power outage generator actually has to run
Start with a list, not a product page. Write down the essentials: refrigerator, freezer, a few lights, phone chargers, the furnace fan if you heat with gas, and the well pump if you have one. Add up the running watts, then double the largest item's starting watts, because motors like a fridge compressor need a surge of two to three times their running draw the moment they kick on.
Most families land between 3,000 and 7,500 running watts for outage basics. That range covers one camp of shoppers, and it explains why 7,500-watt portables sell out first in every storm. If your list includes a well pump, an electric water heater, or a medical device, the number climbs fast and a standby generator starts making sense.
You do not have to guess at this. Our generator size calculator walks your appliance list and returns a wattage target in about two minutes, and it flags the starting-watt surprises for you.
Portable vs standby for power outages
The two routes solve the same problem in different ways, and the honest difference is convenience versus money.
A portable generator for power outages costs $600 to $2,000 and runs on gasoline, with some dual-fuel models adding propane. You wheel it out, start it by hand or with an electric start button, and connect it through a transfer switch or, at the bare minimum, heavy-duty extension cords to individual appliances. It will not run a central air conditioner or an electric dryer, and someone has to be home to set it up. For outages that last a day or two and happen a few times a year, this is the route most households pick. The dual-fuel portables on Amazon are a fair starting sample of this class.
A standby generator is permanently wired to your home, runs on natural gas or propane, and starts itself within seconds of the power dropping. Sizes run from about 10 kW to 26 kW, which is enough to run nearly everything, including air conditioning in the larger units. The catch is the bill: $5,000 to $15,000 installed once you count the automatic transfer switch, a concrete pad, and the electrician. In hurricane country and in rural areas where outages stretch past a week, a standby tends to feel worth it after the first long one. Browsing the home standby listings on Amazon gives a quick feel for where those budgets land.
A middle path exists: a large portable in the 10,000 to 13,000-watt class feeding a whole-house inlet box. You keep manual startup, but the unit can carry most household circuits. Our comparison of generator types breaks down the full cost picture, and if outages in your state are getting longer, the power outages by state data is worth a look before you decide how much machine to buy.
Choosing a generator for house power outage use, step by step
- List the loads. Essentials only on the first pass. Wants like air conditioning go on a second list you may cut later.
- Add the watts. Running watts plus starting surge, using nameplates or the calculator linked above.
- Pick the class. Under 7,500 watts of need points to portable. Over that, or if you want self-starting, points to standby.
- Choose the fuel you can store. Gasoline goes stale in months and is hard to buy during a widespread outage. Propane stores for years. Natural gas only works where the line already reaches your house.
- Budget for the switch, not just the machine. A transfer switch adds $500 to $1,500 installed and is required by code whenever the generator feeds your home wiring instead of cords.
For standby shoppers, dealer support matters as much as specs, since someone has to handle warranty service and annual maintenance. Our guide to Champion whole house generators and the piece on where to buy a generator both cover what to expect from dealers versus big-box retailers.
Three mistakes that make a good generator useless
The first mistake is backfeeding: plugging the generator into a dryer outlet to feed the panel. It can put voltage on utility lines where lineworkers are repairing them, it violates the National Electrical Code everywhere in the US, and it skips the interlock that keeps the generator and grid from ever connecting at once. If the generator feeds the house, it goes through a transfer switch. There is no version of this that is okay to improvise.
The second is running the machine in a garage or on a porch. A generator's exhaust carries carbon monoxide, and fire services across the country report deaths from units run too close to the house every storm season. Manufacturers and the CPSC call for outdoor placement well away from windows, doors, and vents. Twenty feet is the working number most manuals use.
The third is buying on peak wattage alone. A 10,000-watt surge rating on a machine that only sustains 6,500 running watts will not carry what the sticker implied. Size the purchase on running watts against your list from step two, not the big number on the box.
The short version
Match the machine to your list, not to your neighbor's. A portable in the 3,000 to 7,500-watt class with a transfer switch handles outage basics for most houses at a fraction of a standby's cost. When outages run long, when the list includes big loads, or when nobody wants to roll a machine out in freezing rain at night, a standby generator for house power outage coverage earns its price. Size it first, fuel it with what you can store, and never run it closer than the manual allows.
FAQ
Can a portable generator run a whole house?
Not the entire load at once. Most portables sustain 3,000 to 7,500 running watts, which covers essentials but not central air, electric heat, or an electric dryer. Models in the 10,000 to 13,000-watt class come close to whole-house coverage for average homes, with the air conditioner still left off.
What size generator do I need for power outage basics?
A refrigerator, freezer, lights, and chargers run on roughly 2,000 to 3,000 running watts. Add a furnace fan or a well pump and the target moves to 5,000 to 7,500. Run your actual list through a sizing calculator before buying, since starting surges change the answer household by household.
Is a standby generator worth it for occasional outages?
If your outages are short and rare, a portable covers the need for a fifth of the cost. Standby units earn their price where outages last days, where fuel logistics get difficult, or where the household includes someone who cannot manage a manual setup. Check how your state's outage record has trended before committing.
