What’s The Best Sized Generator For My Needs?

A good generator is a great way of getting some high-quality power at any time. They can become an essential whether you’re on the move, camping, out in the garden, or in the vent that your home experienced a power loss.

However, finding a generator that both suits your needs and that’s the correct size can be both a daunting and indeed a difficult task if you don’t know exactly what it is that you’re looking for.

Generators come in all different shapes, sizes, and types. All generators have different power ratings, different points that they excel in, and different things that they are generally better at and more designed to do than other units for example.

In this post, we’re going to focus on the varying generator sizes that are available, what they exist for, and what the primary uses of each size of the generator is. After reading, you should be able to make an informed choice on the size of generator that you need, and that makes the most sense for you to purchase.

When buying a generator, there is no need to spend a large amount more money than you really need to. In the market of power generation, this is a mistake that is not uncommon. New buyers tend to spend an awful lot more money than they really need to, usually due to factors like salesmen selling products that customers do not need to make more money.


1000 watts (1kW) & Less

Generators that are less than 1000 watts in size tend to be great for taking traveling and carrying around in a backpack or something similar.

They specialize in portability, and their aim is to provide quality power from as mobile a little unit as is possible. Whilst not suitable for powering much more than small devices and appliances, the power that they output tends to be of high-quality with minimal harmonic distortion.

The reason that power that’s output by these smaller units is of high quality is because the kind of devices that they’re primarily designed to power are small, and require power that caters to them.

A great example of a generator in this power range is the EcoFlow River 500W. It’s a solar powered generator that provides great-quality power and is extremely portable.

We’ve also included the EcoFlow River 500 in our review of the best solar generators. 

1000 watts – 4000 watts (1kW – 4kW)

1kW – 4kW generators are arguably the most popular available. The devices and appliances that they’re able to power are numerous. They are versatile too since a lot of generators in the power range are fitted with inverters that ensure power that’s suitable for both large and small appliances.

Our favorite generator in this power range is the Honda EU2200i.

5000 watts – 10,000 watts (5kW – 10kW)

 Units that are between 5 and 10kW are very versatile too. Similar to those between 1 and 4kW, a lot of units in this range come fitted with inverters and are still suitable for powering small devices as well as large.

The great factor about generators in this range is that they’re able to power larger machinery, as well as provide backup power to your home in the event of unexpected power loss.

The Honda EU7000iS is a great example of a generator in this range. It’s got an inverter and packs a lot of power. Check out our full review of the Honda EU7000iS right here.

10,000 watts – 15,000 watts (10kW – 15kW)

Generators that are between 10kW and 15kW are starting to become very powerful. This category tends to be split into generators that are designed specifically for providing home backup power, and generators that are designed to design a large amount of mobile power.

The DuroMax XP12000EH, for example, is rugged and is able to provide a lot of power whilst still being mobile.

If it’s a backup generator that you’re looking for, our post on the best standby generators might be able to help you out.

15,000 watts – 20,000 watts (10kW – 15kW)

 Generators in this range are mainly designed to provide home backup power. These generators are often known as home backup generators or standby generators. There are a lot of generators in this range.

We cover the best from this power range in our post on the best whole house generators.

20,000 watts – 40,000 watts (20kW – 40kW)

Generators that are sized between 20kW and 40kW are almost certainly for use as either home backup systems or as an emergency backup power source for a commercial operation.

For example, this large 20kW generator from Briggs & Stratton is at the lower end of this scale It’s designed to provide standby power to a home, in the event of a power cut.

We also have information on what we think are some of the best 25kW generators available, as well as the best 30kW generators available.

40,000 watts – 50,000 watts (40kW – 50kW)

Generators that are between 40kW and 50kW are also extremely large, with specific uses. They are generally not readily available for purchase and must be ordered more in advance than say a 14kW unit for example.

If you are for example a builder or contractor that’s planning the development of a large site that will take a fair amount of time, a generator in this power range is most likely what you will be looking to use.

They are more than suitable for providing backup or indeed constant power to a large site – they will be able to cover all of the electrical needs that you might have.

This Generac SD040 is a commonly used example of a generator that’s in this power range.

We have a short post on 40kW generators here for your information.

50,000 watts (50kW) & More

Generators that are over 50kW in size cover a huge array of products. These sizes of generators are extremely large and are suitable for powering large operations. They can provide power reliably to large operations either permanently, or as a backup source.

Generators this size do not tend to be available in the normal market, and there are fewer of them than say 10kW-15kW units.

For example, the SD050 from Generac is a generator in this power range. It’s massively powerful and is designed to be used in the industry. The amount of uses that a generator with this potential has is endless. However, they’re most certainly not suitable for use in smaller situations where say only 12kW of power is required. They are extremely large and very specialized.

Below are linked some articles that we have written with recommendations on the best generators in various power ranges that are above the 50kW mark.

Best 50kW Generator

Best 60kW Generator

Best 150kW Generator

Best 200kW Generator


The size of generator that you need is very much dependant on the use that you have for your generator, as in how many appliances/pieces of equipment that you’re going to be using it to power at any one time, as well as the type of appliance that you’re looking to power with the generator.

For example, a generator that’s got a maximum power output of 2500 watts would be no use for a builder that needs to power a cement mixer and a drill at the same time. If it’s a 2500 watts generator with an inverter however that’s very portable, it will no doubt be very useful to someone that’s looking for a generator for tailgating.

The main factors that you must consider when you’re looking for a generator and working out what size you need are:

  1. The size of the appliance/device that you would like to power
  2. How many appliances/devices you are likely to need to power at any one time
  3. The type of devices/appliances that you need to power – do they require the power that you’re giving them to have a very low level of total harmonic distortion? If yes, then you should narrow your search to include only inverter generators.

Generally speaking, if you are unsure of the total power output that you are going to need, it is better to buy a larger generator. If you’re unsure and notice after purchasing a generator that only just meets your needs that you, in fact, need more power, you’re going to find that you have wasted an awful lot of money.

Hopefully, we have helped you to work out what size of generator you might need. If you already know which size you would like or what type of generator you would like, we have a large number of posts and recommendations on some of the best from each category.