What Size Generator Do I Need To Run A House for Outages?

The fact you are reading this article means you’ve made up your mind to invest in a backup generator for your house. However, you might also be asking yourself like me when I first purchased mine, “What size generator do I need to run a house”?

Due to frequent floods, hurricanes, wild storms, extreme colds, and other environmental disasters, power outages are becoming common and frequent.

Due to such reasons, the sale of backup generators has increased by more than 50% since 2020.

This surge in demand highlights the importance of having a reliable backup power source for your home. When considering purchasing a generator, it’s important to know what size generator you need to run your house.

How Big of a Generator Do I Need to Run a House?

The size of the generator you need to run your house will depend on your power requirements.

As a rule of thumb, a generator with a wattage output between 5,000 and 7,500 watts can power most essential appliances and electronics in an average-sized home during an outage. However, larger homes with higher power requirements may require a generator with a higher wattage output.

It’s important to calculate your power needs before choosing a generator to ensure that you have enough power to keep your essential appliances and electronics running during an outage.

Before taking a guess, you need to calculate the wattage of your home to find the accurate generator that can run whatever appliances you want it to run.

How to Calculate Watts for The Generator?

It is really simple to do that. The watt is ampere times voltage. It means you need to multiply the amperes of any appliance, by its voltage. You will get watts.

WATT = AMP x VOLT

Suppose your refrigerator is rated at 112 volts and 7 amps, then the total watts it is going consume is:

Watts = 7 x 112

Watts = 784

This is a rough estimation of course because we take starting watts into account as well. All motor-driven appliances have different starting watts and starting watts. Let’s discuss what they are.

Starting Watts and Running Watts

Starting Watts:

Starting, surge or peak watts is the sudden jump of power for a short moment for a motor-driven appliance consumes to overcome inertia to start.

The initial torque of motor-driven appliances takes a lot of power to start.

This is usually a temporary spike in power demand that lasts for a few seconds. For example, when you start a refrigerator or an air conditioner, it requires a higher amount of power to get the motor running.

Therefore, generators are typically rated in terms of their starting watts, as this is the maximum amount of power they can provide for a short period of time.

If you own a fridge, check our article about the generator size required to run a fridge as well.

Running Watts:

Running, rated, or continuous refers to the power an appliance needs to operate continuously.

Recommended Read: What Size Generator to Run a 2000 Sq Ft House?

A Simple Wattage Calculator To Calculate Your Powering Needs

Factors to Consider When Choosing a Generator for a Home?

1. Power Requirements of your Home:

To determine how much power you need, make a list of the essential appliances and electronics that you want to power during an outage.

Add up their wattage requirements to get an estimate of the total wattage you need. I have already explained how can you calculate the total wattage of your home.

This will help you determine the size and wattage of the generator you need.

2. Type of Generator:

Portable generators are smaller and can be moved around as needed. They typically have a lower wattage output and are suitable for powering essential appliances and electronics during an outage.

Standby generators are larger and are installed outside your home, connected directly to your home’s electrical system.

They can provide power to your entire home and automatically switch on when the power goes out.

Standby generators are more expensive than portable generators but offer more convenience and higher power output.

3. Fuel Type:

Generators can run on different fuel types, including gasoline, propane, diesel, or natural gas.

The fuel type you choose will depend on the availability, cost, and storage requirements in your area.

Gasoline is the most common fuel for portable generators, but it has a short shelf life and can be difficult to find during emergencies.

Propane and diesel generators are more efficient and have a longer shelf life but may be more expensive.

Natural gas generators are convenient if you have a natural gas line in your home, but they may require a larger upfront investment for installation.

Apart from that, you don’t need to worry about fuel storage because gas will be available 24/7 and it burns the cleanest, and it is not that expensive compared to other fuel types based on per watt generated.

Spare a few minutes of your time and read this research about generator safety for homes.

4. Noise level:

Generators can be loud and disruptive, especially if you live in a densely populated area.

Look for generators with low decibel ratings if you want to minimize noise pollution.

In general, larger generators produce more noise than smaller generators, so consider the size of the generator when choosing a model with low noise levels.

Anything below or close to 65dB is fine. Standby generators in general are less loud.

Conventional gasoline generators make a lot of sounds, but the latest inverter generators are somewhat less noisy.

5. Maintenance Requirements:

Consider the ongoing costs associated with maintaining and servicing your generator.

Standby generators require more maintenance than portable generators, and you may need to hire a professional for installation and maintenance.

Portable generators require less maintenance but may require more frequent refueling and oil changes.

We have also got an article on the generator size required to run a furnace, and the generator size needed to run a sump pump. Both items are commonly used in medium-sized homes so you might want to check them as well.

What Size Generator Do I Need to Run a House During Blackouts?

The following is a rough estimation of the total watts consumed in a medium-sized home. You may not use all the appliances at the same time but the following table will help you to understand the load distribution.

Common Home Appliances in a Medium-Sized Home

Electronics/Devices	Starting Watts	Running Watts
Refrigerator	1200 Watts	200 Watts
Freezer	800 Watts	250 Watts
Electric Water Heater	4500 Watts	4500 Watts
Sump Pump	1200 Watts	800 Watts
Air Conditioner (2.5 ton)	3800 Watts	1500 Watts
Furnace Fan (1/2 HP)	1800 Watts	900 Watts
Electric Oven	3000 Watts	3000 Watts
Electric Range	3000 Watts	3000 Watts
Dishwasher	1500 Watts	1500 Watts
Washing Machine	1200 Watts	1200 Watts
Electric Dryer	5400 Watts	5400 Watts
Microwave	1000 Watts	1000 Watts
Television	120 Watts	80 Watts
Lights (20x 100W bulbs)	2000 Watts	2000 Watts
Computer and Monitor	400 Watts	200 Watts

Recommended Read: What Size Generator to Run 5 Ton AC Unit?

12000 Watts Generator for Home

Electronics/Devices	Starting Watts	Running Watts
Air Conditioner	3500 Watts	1500 Watts
Desktop Computer	800 Watts	200 Watts
Laptop Computer	0 Watts	60 Watts
Television	120 Watts	80 Watts
Gaming Console	200 Watts	150 Watts
Electric Heater	1500 Watts	1500 Watts
Hair Dryer	1800 Watts	1200 Watts
Iron	1200 Watts	1200 Watts
Electric Oven	3000 Watts	3000 Watts
TOTAL	11,250 Watts	9,550 Watts

• Recommended Read: What can a 12kw generator run?

8000-Watt Generator for Home

Electronics/Devices	Starting Watts	Running Watts
Refrigerator	1200 Watts	200 Watts
Deep Freezer	1300 Watts	700 Watts
Electric Water Heater	4500 Watts	4500 Watts
Sump Pump	1200 Watts	800 Watts
Air Conditioner (2.5 ton)	3800 Watts	1500 Watts
TOTAL	12,200 Watts	7,900 Watts

This estimation is only for running heavy-duty appliances at the same time. You aren’t going to do that of course.

• Recommended Read: What appliances can an 8000 generator run?

Frequently Asked Questions (FAQs)