What Size Generator Do I Need to Power My House During an Outage?

The Southwest Florida area flies into a panic every hurricane season — with good reason. Homes are frequently left without power for days on end and the hope of being prepared “for the next big one” has evolved into a necessity.

Right now, in between hurricane seasons considering what you might need for the future should be at the forefront of your mind. After surviving the last hurricane season,investing in a backup generator is likely something you’re considering. But where do you start?

Read on as we explain generator sizes and their power capacities to help you figure out “watt” you need.

What Does Generator Size Mean?

So, you’ve asked yourself, “What size generator do I need to power my house?” But the word size can refer to a few different measurements.

When talking about generator size, we aren’t talking about its physical size — rather, the size refers to how much electrical power it can supply, measured in watts (W) or kilowatts (kW). What happens if you get the wrong size? Getting an improperly sized generator for your needs can be a costly mistake!

Go too small, and you may not have enough voltage to properly power your appliances. This can damage your appliances and your generator, resulting in expensive repairs and even replacements.

On the other side of the coin, go too big and you’ll throw money away by unnecessarily overpaying for both the unit and the operation costs.

It can be a struggle to figure out the best generator for hurricane season. So, what’s a homeowner to do? Follow these three steps to ensure you’ll be getting just the right generator for your needs.

5 Steps to Finding the Right Size Generator

Step 1: Make a List 

Make a list of all the appliances you want powered in the event of an outage. Here in Southwest Florida, most people make the air conditioner a high priority, along with the refrigerator. Don’t forget to add your smartphone charging station and at least a few light fixtures. Whether you choose to stick with the essentials or go for full home coverage, you’ll need to make a  thorough list so nothing is left out.

Step 2: Determine the Wattage Needed

Next, you’ll need to figure out how much wattage each appliance or light fixture will need. Most appliances will have this information stamped on the appliance or on a sticker, found where the serial number and service information is indicated. More information on where to find the exact wattage details on appliances can be found on the US Department of Energy’s Energy Saver website — along with a helpful energy use calculator.

Using their calculator for this purpose, you are only concerned with the wattage. Please note that this tool provides a sample value only, refer to your specific appliance for a more exact estimate. The hard work is done, now simply add the wattage of the appliances on your list to find the total wattage needed and determine the base level generator you need from that number.

Step 3: Consider Weight 

Now, we can talk about the actual size of generators as it relates to weight. Generally speaking, the larger the generator, the heavier it is. However, this doesn’t mean that it’s more powerful than a smaller one. There are powerful, lightweight, generators that may also make maintenance an easier task. These usually come with a higher price tag, though, so don’t dismiss the heavier and larger ones — especially if these larger models come with wheels and a discount. Choose the size that’s right for you that also meets your energy requirements.

Step 4: Consider Fuel Type and Generator Run Time 

Most generators run on either gasoline or propane, so you need to consider the efficiency of different generators that already meet your wattage requirements. Just like with cars or other engines, you want the most runtime per gallon of fuel.

Additional considerations, such as a good warranty length (like with Kohler), engine type (2-stroke engines vs 4-stroke engines) and having a high-end rectifier for smooth energy, are important too.

Step 5: Don’t Forget About the Noise 

When it comes to the average generator, noise pollution is a real consideration. Take note of the noise rating in decibels when considering the size of your generator. The lower the rating, the quieter the generator. A generator with 80 dB is as noisy as the main street in your city, car honks and all. Shoot for a generator with 60dB or below to save your ears.

The Easy Way…

Generac, a leader in home backup generators and one of the brands Southwest Florida Electric proudly sells, services, and installs, has an easy-to-use online estimation tool. It will help you quickly estimate the right size generator you will need for your home based on your selected appliances, lighting, and extras.

If you want a  big picture overview, you can simply select “whole home” for an idea on what it would take to power your whole home. Follow the prompts in the Generac Home Backup Generator Sizing Calculator to get an idea of what size you may need.

Example: A Tale of Two Homes

John and Jeanette Wilson and The Jones Family both have about 2,000 square foot homes in the Naples area, but have different ideas on what they want covered if there is a power outage.

John and Jeanette want to only power the “essentials” if the power is out. They want to stay comfortable with AC and hot water, but don’t necessarily want to keep their whole house at full running capacity. Here’s their list:

  • 2 Light Fixtures – 175W (far less if they are using LED bulbs)
  • Electric Water Heater – 4000W
  • Central A/C – 4500W
  • Refrigerator – 1500W
  • Phone and Tablet Charging- 30-50W


The Wilson’s should look at an 11kW home backup generator. With an 11kW backup generator, they should be able to run their basics, keeping themselves comfortable, and their food cold and safe from spoilage.

The Jones family wants to power their whole home up, as if there were no outage. They also made a list of the appliances and devices they want powered (it’s a bit longer than the Wilson’s):

  • 15 Light Fixtures – 1225W
  • Electric Water Heater – 4000W
  • Central A/C – 4500W
  • Refrigerator – 1500W
  • Phone andTablet Charging – 50W
  • 2 Laptop Computers – 150Wwi
  • Microwave – 1000W
  • Stove/Range – 3000W
  • Dishwasher – 1500W
  • Clothes Washer – 1500W
  • Clothes Dryer – 1500W
  • 3 LCD TVs – 450W
  • WiFi and Cable Modem – 40W
  •  Garage Door Opener – 2300W


The Jones’ should consider a 25kW generator to power their whole home. There are 22kW backup generators that we carry, but again it is always best to round up – opt for the generator that offers the next step above your estimated kilowatt needs, not below.

If you need some help picking what size generator you need for your house, download our Battle of the Home Stand-By Generator guide to get expert generator insight. If you still have questions, feel free to contact us. Our team is ready to help!


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