These are relatively small machines that can create electricity by themselves. They are critical for off grid jobs, can be used in emergencies for power, and often found being used in leisure activities such as camping and fishing.


Portable generators take stored chemical energy that is found in a fuel such as gasoline, which is used to run an engine. The engine then creates mechanical energy by spinning an alternator. The alternator is an inductor, such as copper, that is inside a magnetic field. The movement of the conductor in the electric field induces a flow of electric charges that is then carried out through wires to the outlet receptacles to be used to operate devices.


When comparing generators, it is important to understand the meaning of, and relationship, between volts, amps and watts. The science behind these terms is deep and complicated, but for the sake of the discussion of portable generators it is best to consider the practical applications.

  • Volts: Can be considered the force, or pressure, of the electricity being applied. In North America, this is set at 120v for most devices, and 240v for the higher energy demand items such as washing machines and dryers. (There are higher voltages available, but those apply to heavier industrial situations and not relevant to portable generators).
  • Amps: If Volts is the pressure of electricity, then Amps would be the flow. Every electric device needs specific pressure (volts) and certain amount of Amps to run. Volts are constant (120v or 240v) and Amps is variable depending on the device. For example, a computer monitor is usually under 1 amp, where as a toaster needs 9 amps.
  • Watts: is the basic unit of power. For electricity this is calculated as Amps multiplied by Volts. Generators are all rated in Watts because once you know the watts, and since voltage is either 120v or 240v (clearly marked on the receptacles) then Amps can be easily determined

Virtually all generators are advertised by Watt output. This needs to be further scrutinized because there are Max/Peak Watt rating, and Running/Continuous watt rating. Max watts is always the higher rating that can be achieved for a few seconds, and can handle the start up energy requirements some devices have. Running watts is what the machine can produce at a steady pace all day long.

Below is a chart showing some times that will have a higher energy demand to get the device started, and those that do not. You will see that the items that need to get something moving, like a fan or a pump will have a higher initial draw. Items with few or no moving parts typically do not have a higher draw at start up.




Air Conditioner 2500 800
Sump Pump 2000 500
Air Compressor 3000 1440
Freezer 2500 500
Electric Fan 600 300




Kettle 1600 1600
Laptop 60 60
Toaster 1500 1500
Radio 80 80
Phone Charger 60 60


For portable generators there are two primary types. Conventional generators which are normally just called ‘generators’ and the new inverter generators often called ‘inverters’.

Generators are far more common. They are easily recognized by having an open frame design and can offer plenty of brute power. If you need raw power, then generators will give you the most bang for the buck.

Inverters are relatively new in comparison. The key difference is that the electricity goes through a power inverter that results in producing much cleaner energy. This is important for the sensitive electronics such as cell phones and computers. Another priority in the design is to keep the inverters compact and ultra quiet. These features drive up the price, but if clean energy and noise reduction are a priority, then these are the machines you want.

Buying Consideration


Conventional Generator

Inverter Generator

SIZE/WEIGHT/PORTABILITY Light weight and portability is an important design goal for all inverters. X
RUN TIMES Because of the smaller size of inverters they have less fuel capacity, which often results in similar run times to compared to the larger conventional generators. - -
FUEL EFFICIENCY The CPU in inverters carefully monitor the demand and adjusts engine speed as needed making them very fuel efficient. Conventional generators either run at idle speeds, or full power when in use. X
MAX POWER OUTPUT Less restraints on the conventional generator design allow much greater output of power. X
QUALITY OF POWER OUTPUT The Inverters process of creating power makes it very clean with minimal distortions that suits sensitive electronics. X
MAINTENANCE Both need to have clean fuel, air filters and exhaust ports as well as regular oil changes. - -
SERVICEABILITY Somewhat debatable, but the over all simpler design and less components of a conventional generator makes them easier to service and repair. X -
PRICE When comparing dollar cost per watt, the conventional generators will always have a better ratio when considering total power output. X