What Size Generator Do I Need For My House?

An average size home requires from 5000 to 7000 watts to power essential items like refrigerators, AC, Lights, Fan, PDAs (laptop, mobile, etc.), FM Radios, TV, Food Processors, Blenders, Washing Machine, Sump Pump, Space Heaters, and others. Please remember you can not run all the appliances at a time if the summation of the appliance’s power is higher than the Generator’s Power. 

Whole house generator or portable generator?

first of all, you should have a clear idea of which type of generator you need.

Who needs a whole-house generator?

A whole-house generator is a backup power system that provides electricity to an entire home during a power outage. While anyone can benefit from having a whole-house generator, there are certain groups of people who may find it particularly useful. These include:

  1. Homeowners in areas prone to severe weather: If you live in an area that is prone to hurricanes, tornadoes, or severe storms, you may experience power outages more frequently than those in other areas. A whole-house generator can provide a reliable source of backup power during these outages.
  2. Homeowners with medical conditions: Individuals who rely on medical equipment, such as oxygen machines, CPAP machines, or dialysis machines, may be at risk during a power outage. A whole-house generator can ensure that these essential medical devices continue to function during an emergency.
  3. Homeowners with home businesses: If you work from home or operate a home-based business, a power outage can be particularly disruptive. A whole-house generator can keep your business running smoothly, even during a power outage.
  4. Homeowners with large families: If you have a large family, the power demands in your home may be higher than those in smaller households. A whole-house generator can ensure that everyone in your home has access to essential appliances and electrical devices during a power outage.
  5. Homeowners with expensive appliances and electronics: Power surges that can occur during power outages can damage expensive appliances and electronics, such as refrigerators, TVs, and computers. A whole house generator can provide protection against these surges, keeping your devices safe.

Who needs a portable generator?

A portable generator is a backup power system that provides electricity to a limited number of appliances and devices during a power outage. While anyone can benefit from having a portable generator, there are certain groups of people who may find it particularly useful. These include:

  1. Campers and RV owners: If you enjoy camping or traveling in an RV, a portable generator can provide power for lighting, cooking, and charging electronic devices while on the go.
  2. Homeowners with limited power need: If you only need to power a few essential appliances or devices during a power outage, a portable generator can be a cost-effective solution.
  3. Homeowners with small properties: If you live in a small home or apartment, a portable generator may be sufficient to power your essential appliances and devices during a power outage.
  4. Contractors and construction workers: Portable generators can provide power for tools and equipment on construction sites where electricity may not be readily available.
  5. Outdoor enthusiasts: If you enjoy outdoor activities, such as tailgating, fishing, or hunting, a portable generator can provide power for cooking, lighting, and entertainment.

Factors to consider when choosing a generator 

When selecting a generator size, several factors need to be considered. These factors include the size of the house, the number of appliances and electrical devices used, the wattage required by each appliance, and the type of fuel used by the generator.

Are you on Offgrid or under a regular electricity connection? 

Well, first thing first. Living in an off-grid farmhouse means you are self-dependent. In this case, solar power is more sustainable and cost-efficient rather than fossil fuel generators. However, you could consider the whole house or standby generators if you prefer generators to solar power. 

On the other hand, if you are under regular electricity and looking for a generator for emergency use or for outing purposes like camping, fishing, etc, then the portable inverter generator is the best choice. 

Types of generators and their sizes:

There are two main types of generators: 

  1. Portable
  2. standby 

Portable generators are smaller and typically run on gasoline or propane. They are ideal for powering a few appliances or electrical devices during a power outage. Standby generators, on the other hand, are larger and are designed to power an entire home. They typically run on natural gas or propane and are permanently installed outside the home.

The size of the generator you need will depend on the type of generator you choose. Portable generators are available in a range of sizes, from 1,000 watts to 10,000 watts, while standby generators range from 5,000 watts to over 20,000 watts. Standby generators are more expensive than portable generators but provide a more reliable and convenient source of backup power.

Based on running the sensitive electronics, generators are mainly 2 types. 

  1. Inverter generator 
  2. Non inverter generator

Inverter generators are safe to run every type of appliance including sensitive electronics like mobile, laptop charging, camera gear charging, etc. They are a bit more expensive than the portable non-inverter generator. But they produce low noise and offer more features than the regular generator. 

Non-Inverter generators are less expensive than inverter generators. You will get up to 2000 watts to the 12000-watt portable generators on the market. Non-inverter generators don’t produce a pure sine wave. So, they are not perfect for running sensitive electronics. 

Based on the Fuel, generators are 3 types. 

  1. Propane generator 
  2. Gasoline generator 
  3. Dual fuel generator

Propane generators are more convenient than gasoline generators for long use. If you need alternative power regularly for different types of DIY work, then you could consider propane generators. 

Gasoline generators are also good. Basically, there is no basic difference between these two. If you have enough supply of gasoline you could consider the gasoline generator. 

Dual fuel generators are for smart people. Yes, they are a bit more costly than the other two types as you get more options here. If you have no budget issues, you could consider dual-fuel generators.

The size of the house:

The size of the house is an essential factor in determining the right size generator. A larger home will require a more powerful generator than a smaller home. Larger homes have more electrical devices, such as air conditioners, refrigerators, and water heaters, which require more power to operate.

The number of appliances and electrical devices used:

The number of appliances and electrical devices used in a home is another crucial factor. Homes with many appliances and devices will require a more powerful generator to ensure that everything continues to function correctly during a power outage.

The wattage required by each appliance:

Each electrical device and appliance in your home has a specific wattage requirement. It is important to add up the wattage requirements of all the devices that you want to run during a power outage to ensure that your generator can handle the load.

Calculating the size of the generator needed:

Calculating the size of the generator you need is relatively straightforward. First, determine the wattage requirements of each device and appliance that you want to run during a power outage. Next, add up the wattage requirements to determine the total wattage required. Finally, choose a generator with a capacity that exceeds your total wattage requirements.

For example, if your home requires 10,000 watts to operate, a generator with a capacity of at least 12,000 watts would be suitable. It is important to note that the capacity of the generator should exceed the total wattage required to account for starting watts. Some devices, such as air conditioners and refrigerators, require more power to start than they do to run continuously.

things to consider before finilazing the generaor size for your home

How long will you power Up your appliances with a generator? 

Another important topic that you should consider before buying a generator. Because you can not run a small portable generator all day long. It will definitely show a mechanical error when it can not handle the demand. 

The small portable generator is designed for running for less than 10-12 hours continuously. The time varies from brand to brand. 

So, you should finalize the demand initially. 

How much electricity actually do you need? 

So, you should count the wattage of your electronics. Every electronic appliance comes with a running and starting watt. Starting watt is higher than the running watts. 

You will get the exact figure on the level of the appliance. Or you could search for the model number of the particular brand on the internet. 

Now, you need to list down all your appliances and summarize the total watts of your appliances. Say for, your appliances consume 7000 watts altogether. You should count it at least 100 watts higher than the number when buying the generator. 

Understanding the Difference Between Watt and Volts and Amps

Watt is the SI unit of power. It is named after James Watt. Watt measures the rate of energy transfer. 

Volts mean pressure. That means how strongly the current passes through the circuit. So, the higher voltage means a greater flow of the electrical current. 

On the other hand, Ampere is the SI unit of current. It measures the rate of electron flow. It indicates how much power an appliance needs. 

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Understanding the starting and running watt 

Most electrical appliances come with different starting and running watts. The starting or surge watt is a bit higher than the running watt. When the appliances like the freezer, heater, or AC start completely, they need lower power to continue. 

In some cases, the difference between starting and running watt is large. Especially for the heater, AC, Dish Washer, Central AC, Electric Stove, etc. 

So, beware of the starting watt and running watt before buying a generator for your home. If you are planning to run all the large appliances during the power outage, it would be great to buy at least a 1000-watt higher generator than your needs. 

How Many Watts Do Common Appliances Use?

The rule of thumb for running electric appliances is that the total wattage consumed by all appliances in your house should not exceed half the maximum power output (watts) of your generator.

That means, if all of your appliances consume 5000 watts, then you should go for a 10 thousand watts generator. Yes, 10 thousand-watt portable generators are available in the market. But for typical home use, 5000 to 7000 thousand watts is enough. If you need extra power, then go for the more powerful generator. 

Here is the list of common starting watts and running watts of mostly use appliances. Anyway, the watt can vary from brand to brand and power outage. It is only for getting an idea. 

Home AppliancesStarting WattRunning Watt
AC (10000 BTU)22001500
Oven (800 Watt)13001300
Sump Pump (.5 hp)21501050
Garage Opener1420720
DVD Player350350
Cell Phone Charger2525
Ceiling Fan1200800
Central AC (3 ton)75003000
Electric Water Heater40004000
Washing Machine22501150
Vacuum Cleaner11001100
Coffee maker600600
Toaster Oven12001200
Electric Grill16501650
Slow Cooker250250

How to select the right generator Size and Type? 

So, you have elementary knowledge about the generator now. Now, it is time to decide what kind of generator you should buy. 

If you need to run small sensitive appliances like laptops, TV, woodworking tools, and others, you should consider the Inverter generator. With an inverter generator, you can go camping without any tension on the supply of electricity. 

On the other hand, if you just want to back up the most important appliances in the power outage like the freezer, AC, Dishwasher, etc, then you could go for the portable generator without an inverter generator. 

Now, it’s time to consider which generator should I choose. 

Why should you choose the right generator for your home? 

Choosing the right generator for your home is essential for several reasons, including:

  • Ensuring uninterrupted power supply: The right generator will provide sufficient power to keep essential appliances and devices running during a power outage, ensuring that you and your family are not left in the dark.
  • Protecting your appliances and electronics: The right generator will provide clean, stable power that will not damage your appliances and electronics during an outage.
  • Saving money: Choosing the right generator will ensure that you are not paying for a system that is too big for your needs or one that is too small and unable to meet your power requirements.
  • Improving safety: A properly sized generator will reduce the risk of accidents, such as electrical fires or carbon monoxide poisoning.
  • Peace of mind: Knowing that you have the right generator for your home will give you peace of mind during a power outage, knowing that you and your family will be safe and comfortable until power is restored.
  • Increased property value: A home with a properly installed and maintained generator can be a selling point for potential buyers, increasing the overall value of your property.

In summary, choosing the right generator for your home is essential to ensure an uninterrupted power supply, protect your appliances and electronics, save money, improve safety, provide peace of mind, and increase the value of your property.


Can A Portable Generator Run A Whole House?

Yes, if your home is not too large you can run your whole house with a portable generator. Some of the renowned portable generator brands like Champion produce 12000-watt portable generators. So, if your power consumption is under this line, you could power your whole house with a portable generator. 

How Much Does A Whole House Generator Cost?

The average cost of a whole house generator is 5000 USD in the US. It may vary from area to area. Also, it depends on the size of your home and what types of appliances you want to run. However, the cost is limited from 5000 USD to 25000 USD. 

Will A 7500-Watt Generator Run My House?

Yes, you could run the appliances of your house with a 7500-watt portable generator. As I mentioned earlier, for getting the maximum performance you should not exceed the 3750 watts line. That means the summation of the output watt of your appliance should not exceed 3750 watts to get the maximum performance from a 7500-watt generator. 

Will A 9000-Watt Generator Run A House?

Yes, you could run your house with a 9000-watt generator. With a 9000-watt generator, you can run almost every home appliance including the Central Air, Sump pump, Dishwasher, AC, and all other small appliances of your home. 

What size generator to run a 1500-1800 sq ft house?

It depends on the demand of how much power you need. Some people run their major appliances on natural gas like furnaces, ovens, dryers, hot water heaters, and others. So, they just need to run their freezer, light, and AC with the electricity. Your demand may be different from theirs. However, 2250 watts to 4000 watts generator should be enough to run your 1500 sqft house. Although you may not run all the appliances at once. 

What size generator to run a 2000 sq ft house?

A 2000 squire ft house is enough space to use all types of necessary appliances like refrigerators, freezers, air conditioners, microwave ovens, electric stoves, LED bulb fans and etc. If you want to run all the home appliances you will need approximately 5000-8000 watt running watts. That means you need an 8000-watt to 10000-watt starting-watt generator. 

On the other hand, if you just want to run only the basic appliances like refrigerator, lights, etc during the power wattage, 3000 watts to the 5000-watt generator is enough. 

what size generator do I need for a 2,500-square-foot house?

An atypical 2500 square foot house needs a 5000-8000 watt running watt. to run all your basic appliances including refrigerator, freezer, internet router, Directv box & TV, small drinks refrigerator, microwave oven, AC, and other small appliances. Just make sure that the starting watt of these household appliances doesn’t cross the power of your generator. So, the actual size depends on your needs. 

What size generator do I need for a 3000-square-foot house?

3000 sp ft house with fully packed appliances needs a whole house generator to run all the appliances at once. But if you don’t want to run all your appliances during a power outage, you can back up your house with a large portable generator like a 12000-watt generator. Actually, it depends on your appliances. With a 12000-watt generator, you can run almost all the necessary home appliances like the sump pump, AC, heater, dishwasher, central air, furnace, and all the other home appliance. Yes, you can run all the appliances at a time but you can survive a prolonged power outage. 

Final Thoughts 

So, you could go for a powerful generator like a 10000 or 12000 starting-watt portable generator to power up all your appliances. On the other hand, if you are looking for a solution including your sensitive electronics, then no doubt the inverter generators are the best solution. 


Rayan is an engineer, lives in a farmhouse. He has a passion for electronics and alternative energy. He loves to share his thoughts with other people. That is why he started the blog.

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