Portable Generator Buying Guide

If you're looking for the best portable generator then there are a few things to keep in mind. Power output, features and noise level are all important factors to consider. In this buying guide we'll give you a brief overview of what to look out for.

Your quietest option will always be an inverter generator rather than a conventional generator. This is why most quiet generator reviews only list inverter types.

Here are the main differences between an inverter generator and a regular generator.

Generator type - conventional vs inverter

Standard Generator

A standard generator runs on either diesel or gasoline, with diesel being the loudest generator option by a long way. A standard generator will run at a constant speed regardless of the load that is being drawn from it.

This results in a constant level of noise coming from the generator. The petrol powered engine rotates an alternator and it puts out 120V AC power.  These are the more old school generator types. They are reliable and cheaper but very noisy.

Inverter Generator

Inverter generators are the newer type of quiet generators and incorporate smart electronics to improve efficiencies and noise levels. These generators also have a gas engine but they convert the initial AC power into DC and then back to a clean 120V AC output.

The way that they do this allows the generator to run at lower revs making it a lot quieter. The electronic controls also allow the generator to throttle its speed according to the load.

This means that when you’re drawing less current from it the generator will be a lot quieter than when it’s at maximum output.

There’s no such thing as a “silent generator” but an inverter generator is as quiet as it gets.

What Type Of Generator Do I Need?

Choosing the right generator for your needs really comes down to power output and physical size. If you’re looking for the best home standby generator or for more industrial use then you’re probably not too concerned about how portable it is.

In this case it’s more about having enough power to run your household while the power is down.

If you want portable generators for camping, RV use, tailgating or other recreational activities then you’re going to be more concerned with getting the lowest noise option. There are some things you can do to make your generator more quiet.

The output of these will normally be around 2000W which is fine for most recreational activities. These quiet small generator units are easy to fit in the trunk of your vehicle and are easy to carry around to wherever you’re going to set up.

Power output - What size generator do i need?

Portable Generator Sizing Chart

Generator manufacturers will normally quote the engine capacity of the engine in the generator but it’s the power output that is most important.

Generator output power is quoted in Watts (W). When comparing inverter generators it’s important to understand the difference between starting Watts and running Watts. 

Generator Starting Watts

The peak power that you can get from a generator when revs up to its maximum is the figure that is always quoted in the product name or description. Starting Watts refers to the peak power the generator can put out for a short period of time.

This is also sometimes referred to as the surge power, or surge capacity, of a generator. These are also the figures that are used in the generator model numbers.

This power output is an indication of the amount of power the generator can supply if there is a sudden surge when a device connected to it starts up. The generator will not be able to sustain this for more than a brief moment. 

Generator Running Watts

This is the maximum, ongoing, power that the generator will be able to deliver.

Sometimes you’ll see that the description of portable generators quotes two numbers. The first will be the starting wattage while the second, lower figure, will be the running wattage.

Both starting wattage and running wattage figures are important to take note of.

To illustrate, if you are running an AC in your RV it could draw 1,800W when it starts the compressor up and then settle down to drawing around 1,200W while running.

Your generator needs to be able to supply both the peak power required as well as the continuous power required. It’s always a good idea to allow for 10% - 15% more than the maximum power you will require.

Quiet Generator Voltage Outputs

Generator output voltages

A quiet generator will always have one or more 120V AC outputs with household outlets. If you want an RV generator then you need to make sure that the generator has an RV outlet that is rated high enough to cater for your RV.

Some of the best portable generators will also have 12V DC outputs as well as USB outputs. These can be very convenient for charging your phone or other devices without having to carry extra chargers.

Generator Protection

GFCI - Ground Fault Circuit Interrupter also known as a Residual Current Device (RCD). If a generator has built-in GFCI protection then it will switch the generator off if current flows through an unintended path, like you.

Generator Fuel Efficiency

fuel gauge

The best quiet portable generators reviewed above mostly have a fuel tank of around 1 gallon. How long will this fuel last? 

Well it really depends on how hard the generator is made to work. A regular generator rotates at a constant speed so it’s simple to state an amount of hours per tank of fuel.

An inverter generator has a smarter throttle and will speed up and slow down depending on the load. To make comparisons between these kinds of generators simple the fuel efficiency is quoted as hours per tank at 25% load.

When comparing quiet generator run times take the fuel tank size into account. Take the quote run time in hours and divide it by the tank capacity.

This will give you an “hours per gallon” figure which will give you a better idea of comparative fuel efficiency. Just remember that this comparison only holds true when comparing generators with the same output power.

Generator EPA and CARB Compliance

Closely related to generator fuel efficiency are the EPA and CARB certifications. These certifications are only given to the most efficient generators that meet strict emission controls.

If you live in California then you need to be sure that you buy a CARB compliant generator. If you buy a generator online and it isn’t CARB compliant then the supplier won’t be able to ship it to you.

Eco-mode throttle - regulates engine speed as devices are plugged in and out so that the generator only uses as much fuel as is absolutely necessary.

Sinewave Technology - Just saying that a generator puts out 120V AC doesn’t really tell you much about the quality of the power you’re getting from it.

You want the output voltage to follow a perfect Sinewave as far as possible. This is especially important if you’re going to be plugging sensitive equipment like your laptop into the generator.

Some generators put out what is called a “modified sine wave” signal. These are normally fine for running lights or a stove plate but not good for sensitive electronic chargers.

If you’re going to be charging your laptop or camera then check that the generator puts out a true sine wave.

You’ll also see that some generator specs mention THD, or Total Harmonic Distortion. Without getting too technical, this is just a measure of how “clean” the signal coming out of the generator is. If the THS is below 3% then it’ll be fine for your sensitive electronics.


Some of the information above may seem a little technical but it's worth having at least a partial understanding of these things before buying your generator. Understanding your power requirements is the first place you should start. After that it really comes down to the quality of the supply and how much your budget will allow for.

    David Miller

    David is a health conscious and houseproud family guy. When he's not being used as a jungle gym by his kids you can find him working on his latest DIY project in the garage.