The choice between a portable generator and a standby generator is really a choice between effort and money. A portable unit asks for your time during every outage. A standby unit asks for a large sum up front and then asks nothing. Which is right depends on how often the power fails, what has to keep running, and who is at home when it happens.
Quick answer
Choose a portable generator if outages are rare and short, you can manage without central air conditioning, and someone able-bodied is usually home to set it up. Choose a standby generator if outages are frequent or long, you want the whole house covered automatically, anyone at home depends on powered medical equipment, or the house is often empty.
| Factor | Portable generator | Standby generator |
|---|---|---|
| Typical output | 3,000 to 12,000 W | 10 to 26 kW air-cooled, larger liquid-cooled |
| Starts | You start it, by cord or button | Automatically, within seconds |
| Fuel | Gasoline, propane, sometimes diesel | Natural gas or propane |
| Run time | 8 to 12 hours per tank, then refuel | Days or weeks on natural gas |
| Connection | Extension cords, or inlet with transfer switch or interlock | Automatic transfer switch, hard-wired |
| Installation | Inlet and switch by an electrician, or none | Pad, electrical, gas plumbing, permits |
| Noise | Loud, 68 to 80 dB(A) for open-frame | Moderate, mid to high 60s dB(A) |
| Maintenance | Oil every 50 to 100 hours; exercise monthly | Self-exercises weekly; annual service |
| Works when you are away | No | Yes |
| Cost | Hundreds to low thousands | Many thousands installed |
In this guide
Convenience
This is the decisive difference. When the power fails at 2 a.m. in an ice storm, a standby generator has the house back on before you find a flashlight. A portable generator means getting dressed, wheeling it out, connecting the cord, starting it, and then refueling it every eight to twelve hours for as long as the outage lasts. If that is a realistic plan for your household, a portable saves a great deal of money. If it is not, the standby unit’s cost buys genuine peace of mind.
Power
A portable generator in the 5,000 to 7,500 W class runs the essentials in most homes: refrigeration, a furnace blower, pumps, lights and electronics. It will not run central air conditioning or an electric water heater on top of those. A standby generator of 18 kW or more can carry a whole house, including air conditioning, and load-management features let a smaller unit cover more than its rating suggests. Use our generator size calculator to see which side of that line your loads fall on.
Fuel
Portable generators run mainly on gasoline, which you must store and rotate, or propane cylinders. Standby generators connect to a natural gas line or a large propane tank, so they can run for days without anyone carrying fuel. In a widespread outage, when gas stations are closed and propane exchanges run out, that difference matters as much as the automatic start.
Installation and cost
A portable generator needs no installation if you are content with extension cords. Adding an inlet box and a manual transfer switch or interlock is a modest electrical job. A standby generator is a project: a concrete or composite pad, the transfer switch at your panel, a gas line sized for the generator, permits and inspection. Installation commonly costs as much as the generator itself. Our guide to whole-house generators covers what to expect and what to ask installers.
Maintenance
Both types need oil changes, filters and a battery kept charged. The standby unit does most of its own checking by running a short exercise cycle every week, and owners typically have it serviced once a year. A portable generator depends on you to exercise it and to deal with stored fuel. Manufacturers’ troubleshooting guides put stale fuel at the top of the list of reasons a portable will not start, which is why we suggest dual-fuel models for standby duty.
Noise and neighbors
Standby generators sit in sound-attenuating enclosures and run at about the level of a central air conditioner. Open-frame portables are much louder, and their placement 20 feet from the house usually puts them near a property line. In dense neighborhoods this alone pushes some owners toward a standby unit or a quiet inverter.
Resale and property value
A professionally installed standby generator stays with the house and is a selling point in areas with unreliable power. A portable generator goes with you when you move.
The middle ground
Many households land between the two: a large portable or inverter generator, a 50 A inlet box, and an interlock or transfer switch. For a fraction of the cost of a standby system, it covers the essentials and even a window air conditioner, and it can be set up in ten minutes. The compromise is that it still needs you to be there. Read how to connect a generator to your house for the details.
Frequently asked questions
Is a standby generator worth the money?
It depends on how much you would pay to never think about outages again. For homes with frequent or long outages, medical equipment, a sump pump protecting a finished basement, or owners who travel, most people who install one say yes. For a rare outage of a few hours, a portable generator is the better value.
Can a portable generator power a whole house?
A large portable of 10,000 to 12,000 W connected through a 50 A transfer switch can run most of a house if you manage the loads, but central air conditioning and electric heating usually push the total beyond what a portable can supply.
How long does a standby generator last?
With annual service, air-cooled home standby generators are commonly expected to give many years of service and thousands of running hours. Liquid-cooled units last longer still under heavy use. Follow the maintenance schedule in the manual.
