How Big of a Standby Generator do I Need?

No one enjoys losing power at their home or place of business. For many of us it is a rare event that we experience after a strong storm passes by. In most cases the power comes back on an hour or two later and we think nothing of it. Some who are a bit more prepared  may have a portable generator in storage that we dust off every once and a while to keep things going.

There are some of us though who experience power losses frequently and when they do occur the power could be out for days at a time. This is not only a major pain but it can also have other impacts. When the power is out for a substantial amount of time you could see all of the food in your refrigerator and freezer go to waste. Along with that your air conditioner or furnace will not function.

A few years back my family and I purchased a small farm way out in the Kansas country. It was very remote and one of the most peaceful places I have ever lived. The downside was that when a storm rolled through the chances of us losing power were high. When the power did go out it was often out for a significant amount of time. Since we were so rural we were not at the top of the list to get power restored.

It was during this time that we began to seriously look at purchasing and installing a standby generator system. When installed these units will automatically switch on when your home’s power goes out. The moment your power goes out you will see a slight flicker in the lights and presto, your standby system has activated. You now have power throughout your home. These standby systems are definitely the ‘easy button’ when it comes to restoring power.

There are also a lot of questions when it comes to these machines. How much do they cost? What should you look for? What does the install look like? Over the past few weeks we have tackled these topics on standby generators one by one. In today’s article we are going to focus on a big one: What size of standby generator should you purchase? Let’s dive in and take a look.

Sizing Your Standby Generator

Now before we can size your standby generator we first have to review a couple of questions. Just like with many other things sizing a standby generator is not a clear cut simple answer. There are many variables that have to be reviewed and considered before you can accurately size your system. If you purchase a system that is sized too small then you will NOT be able to power everything you wish in your home. Or, if you purchase a system that is too large then you will be wasting money as well as fuel efficiency.

One of the most vital questions is what do you hope to accomplish with your standby system? Do you wish to power everything in your home including all major utilities? Or, do you only wish to power a few appliances and electronics? The answer to this question is going to directly determine how large of a system that you need. Obviously, if you are just looking to have a backup for a few appliances then you will need a much smaller size when compared to trying to power your whole home.

The next question that you need to review is just how large is your home? The larger the home the larger the size of generator that you are going to need. This is a given. Standby generators sizes are measured in kilowatts. An example of this would be a twenty kilowatt model. For an example, lets say that you have a twenty-five hundred square foot home. This sized home would need a generator with an estimated size of twenty-two kilowatts.

Using another example, let’s say that your home is fifteen-hundred square feet. With this size home the estimated standby generator would need to be fourteen kilowatts. Or, say you only want to power a few things in your home instead of the entire home. You may be able to get away with a seven kilowatt standby system. Or, going with the other extreme let’s say you want have a very large home at three or four-thousand square feet. Maybe it is a business you are trying to power. These larger sized buildings could require an estimate of forty kilowatts.

The above examples I gave were very broad but they should give you a kind of idea on what type of standby generator your home would need. To get a bit more specific though there are generator calculators out there that allow you to add up all of your appliances and electronics in your home. It gives you an estimate of each appliance and when it is all said and done it gives you an estimated wattage used. This can then be used to determine the standby generator that you need.

My two favorite generator calculators are this one from Generac and this one from Champion. Both are great at providing you with estimates. I would recommend using both of them so that you can get two opinions on your sizing needs. This gives you the second opinion before you end up committing to something. Remember that it is best to go twenty or thirty percent higher on wattages then the estimate. This gives you wiggle room if you forgot something. It also gives you room to add appliances to your home down the road.

Notice how I said estimate when using these examples? I said this as each home is unique. I can provide estimates to you all day long but they are just that, estimates. It is impossible for me to tell you exactly what your home needs. There could be a significant difference between you and your neighbors house. Perhaps they have an energy efficient air conditioner that uses less power then yours. There are just so many variables out there.


As you can see from above folks there are a lot of variables that goes into sizing your standby system. While the links we provided above are great for reference they are not to be taken as gospel. If you are truly looking at purchasing a standby system then I am going to highly recommend that you reach out to a certified dealer and get their expert opinion. There are many reputable brands out there to choose from, I personally though prefer the Generac brand. They are the biggest generator brand out there today and they have a great reputation of standing behind their products.

I hope this article was helpful and thanks for reading,

Alec Johnson


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