How Much Wattage Do I Need in My Portable Generator?

Many of us are familiar with technical measurements and units but unable to picture them in a meaningful way. Guess the size of Australia, for example. It’s big for sure, but it’d be easy to make an estimate in km² that’s way off target.

The country actually covers more than 7.5 million km².

In a similar way, you might understand wattage or watts as units of power. But, how much is a lot? 1000, 5000 or 8000 watts?

The electrical power you need will depend on what you intend to run off your portable generator. Read on to find out which generator size is for you and your needs.

Why Understanding How Much Power You Need is Important

Before we drill down into the figures, it’s important to understand the impact of under or over-estimating the power you need. There is an argument for purchasing a portable generator rated for a maximum load higher than you ever anticipate reaching: the principle being that it is better to have extra capacity than to have too little.

However, if you choose a generator that is way too big, you’ll pay more in your initial outlay for extra capacity you don’t need. Installation, fuel consumption and maintenance may also become more costly.

On the other hand, if you choose a generator that is too small, you won’t be able to run heavy-duty items like fridges when there’s a power outage. And, if you overload the generator, you might cause a breakdown along with damage to any appliances using its power.

Running and Startup Power

Boiling it all down, the size of any of the quiet petrol generators you buy will depend on the number and type of appliances you intend to run. Some equipment needs a lot of power to start up, but, once it’s running, it will cruise along on much less power.

Running lights and the odd power tool, for example, will require less start-up power than fans, fridges and aircon units. As a rule of thumb, items with a motor typically need extra watts to get going but then less to carry on running.

A Handy Guide to Appliances and Wattage Requirements

Here are 2 lists containing some of the more common examples of home appliances that you might need to power from a generator. Items in the first list do not require extra power that can cause a surge when you power them up. Items in the second list do require extra start-up power.

LIST 1 (No Extra Starting Watts Needed)


Running Watts

Gardening Trimmers:                              500 watts

Lawnmowers and chain saws:              1200 watts

70w Light Bulbs:                                       70 watts

Computer with 17” screen:                     450 watts

Security System and Colour TV (27”):    350 watts

Coffee Maker:                                       1000 watts

Electric Kettle:                                       2200 watts

Lamps:                                                    100 watts

Electric Stove (6” element):                   1600 watts

2 x smartphone chargers                          50 watts


LIST 2 (Extra Starting Watts Needed)


Running Watts                          Starting Watts

Medium Fridge/Freezer:                 350 watts                                        700 watts

Microwave (750w)                             750 watts                                         950 watts

Well Pump                                           500 watts                                      1000 watts

½ HP Garage Door                            450 watts                                       900 watts

Washing Machine                              750 watts                                      1500 watts

Sump Pump ½ HP                             500 watts                                      1000 watts

Fans                                                     200 watts                                         400 watts


Electric kettles are one of the biggest wattage guzzlers in the home. If you can heat water with a portable gas appliance when your generator is in use, so much the better.

A Key Benefit of Maxwatt Petrol Generator Sets

You should never overload a portable generator. All Maxwatt portable petrol generators can, however, offer a surge to their regular output. This is always for a short period of time, during startups, for example.

Take the 13.5kVA Maxwatt generator. It can deliver up to 10000 running Watts and 11000 starting Watts. When generators run for prolonged periods with an overload, several problems can crop up. These include:

  • The engine overheating
  • The alternator overheating causing the windings to burn out
  • A breakdown in oil consistency leading to engine failure
  • A reduced lifespan for the generator

How to Calculate the Number of Watts You Need

Let’s look at the Maxwatt 8000-watt generator. It can provide 8000 starting watts and 7000 running watts. It can run as many appliances at one time as you want. That’s provided the total number of starting watts is less than 8000 and the total running watts are less than 7000 watts.

You should make your calculations well in advance so that there’s no room for error in an emergency. You could even make your own chart with the starting and running watts of all of your own devices.

Create a list of all the appliances you will need or want to run if the electricity is out for a short or long period. Tot up the wattage needed and ensure it is less than the maximum your portable generator can comfortably cope with.

Weight, Noise and Electric Start

As well as wattage, the weight and noise of a generator can play into the decision about which you choose. One person can easily carry our smallest models using the integrated ergonomic lifting handle.

Our bigger models have multiple lifting points. Their “Never-Flat” wheels and handles make moving them around a breeze. We’d always recommend handling them as a 2- person lift or by a single person using a mechanical aid.

Our inverter generator models are the quietest in our product range. The low-tone mufflers, ECO-throttle switch and double-insulated acoustic enclosure mean these units run super-silently from only 59 dB(A).

These Maxwatt models are electric start: MX3000IY/ 4500IS/ 6000IS/ 6500IS/ 7000ES/ 9000ES/ 9000AS/ 8000IS/ 13000AS. We’ve fitted them with a 12 Volt battery, but you can also start them manually using their built-in recoil starter.

Maxwatt Petrol Generators Have You Covered

Maxwatt offers a wide range of portable generators. The generator size you choose will depend on the number of appliances you plan to run and the wattage each appliance requires.

You can see all the different, quiet generators we have available here. Check your wattage needs and make your selection today.


Tags: , , , , , , , , , ,