What Watt Generator Do I Need To Run My Whole House?

Are you wondering what watt generator you need to power your entire house? Look no further! In this article, we will discuss the different factors to consider in determining the right generator wattage for your home. Whether you’re preparing for a power outage or simply want a reliable backup source, understanding the appropriate wattage will ensure your electrical needs are met. So, sit back, relax, and let’s find the perfect generator for your whole house.

What Watt Generator Do I Need To Run My Whole House?

Calculating Wattage Requirements

Step 1: Determine the Essential Appliances and Electronics

To calculate the wattage requirements for your whole house generator, you first need to determine the essential appliances and electronics that you want to power during a power outage. Make a list of all the appliances and electronics that are necessary for your daily activities, such as refrigerators, air conditioners, heating systems, lights, well pumps, and kitchen appliances.

Step 2: Determine the Starting Watts and Running Watts

Once you have identified the essential appliances and electronics, you need to determine their starting watts and running watts. Starting watts refer to the initial surge of power needed to start an appliance or electronics, while running watts refer to the power required to keep the appliance or electronics running.

You can find the starting watts and running watts information in the product manuals or specifications of each appliance or electronics. If the information is not readily available, you can also contact the manufacturer or consult an electrician for assistance.

Step 3: Add Up the Required Watts

After determining the starting watts and running watts for each appliance and electronics, you need to add up all the required watts to calculate the total wattage requirements for your whole house generator. This will give you an idea of the minimum generator size needed to power your essential appliances and electronics during a power outage.

Considerations for Whole House Generators

Backup Power vs. Whole House Generator

When choosing a generator for your whole house, you will have to decide between a backup power system or a whole house generator. A backup power system typically consists of a few selected circuits that are connected to the generator, providing power to essential appliances and electronics. On the other hand, a whole house generator is designed to power your entire house, including all the circuits.

If you want the convenience of powering your entire house during a power outage, a whole house generator is the best option. However, if you only need essential appliances and electronics to be powered, a backup power system can be a more cost-effective choice.

Automatic Transfer Switch (ATS)

To ensure a seamless transition from utility power to generator power during a power outage, an automatic transfer switch (ATS) is essential. An ATS will automatically detect the loss of utility power and activate the generator, supplying power to your house. It also ensures that only one power source is used at a time, preventing damage to the generator and the electrical system.

When sizing your generator, it is important to consider the power requirements of the ATS. The generator should have enough capacity to handle the starting watts and running watts of both the essential appliances and electronics, as well as the ATS itself.

Are Portable Generators Suitable?

Portable generators are a popular choice for providing backup power during a power outage. They are compact, easy to transport, and typically less expensive compared to whole house generators. However, portable generators may not be suitable for powering an entire house.

Portable generators generally have lower power outputs compared to whole house generators, making them more suitable for powering a few selected appliances or electronics. If you choose to use a portable generator for your whole house, you will need to carefully manage the power load and prioritize essential appliances and electronics.

Fuel Options and Consumption

When selecting a whole house generator, it is important to consider the fuel options available and their consumption rates. Common fuel options include natural gas, propane, and diesel.

Natural gas and propane are commonly used for whole house generators as they offer a continuous fuel source, eliminating the need for refueling. However, it is important to check if natural gas or propane lines are available in your area.

Diesel generators can also be used for whole house backup power, but they require regular refueling and may not be the most cost-effective option in the long run.

Consider your fuel options and consumption rates when choosing a generator to ensure you have an adequate fuel supply to power your whole house during an extended power outage.

Sizing the Generator

Minimum Generator Size

The minimum generator size you should consider for your whole house backup power needs will depend on the total wattage requirements calculated in the previous step. Ideally, you should choose a generator that has a capacity slightly higher than your total wattage requirements to accommodate any additional power needs or future upgrades.

Under-sizing the generator can lead to overload situations, where the generator is unable to handle the power demand, potentially causing damage to the generator or the appliances and electronics connected to it.

Backup Power Considerations

When sizing a generator for backup power, it is crucial to consider the specific power requirements of your essential appliances and electronics. Some appliances, such as air conditioners or heating systems, require higher starting watts compared to running watts. Failing to account for these higher power demands can result in a generator that is unable to start and run these appliances.

It is also important to consider any additional power needs or power surges that may occur during a power outage, such as powering electronics or charging devices. Including a buffer in your generator size calculation will ensure that all your power needs are met during a power outage.

Determining Generator Size Based on Amps

Another way to determine the generator size for your whole house backup power is by calculating the total amps of the appliances and electronics you want to power. This can be done by dividing the total watts by the voltage of your electrical system.

For example, if your total wattage requirement is 5000 watts and your voltage is 120 volts, the total amps would be 41.67 amps. You would then need to choose a generator that can handle a continuous load of at least 41.67 amps.

Sizing Guide for Common Appliances and Electronics

To help you estimate the wattage requirements of common appliances and electronics, here is a general sizing guide:

Air Conditioner

A central air conditioner can require anywhere from 3,000 to 6,000 starting watts and 1,500 to 3,500 running watts, depending on the size and efficiency of the unit.


A typical refrigerator can require around 600 to 800 starting watts and 100 to 400 running watts.

Heating Systems

Heating systems, such as furnaces or heat pumps, can require anywhere from 800 to 2,500 starting watts and 500 to 1,500 running watts, depending on the type and size of the system.

Well Pump

A well pump can require around 1,000 to 2,500 starting watts and 500 to 1,500 running watts, depending on the depth and size of the well.


The wattage requirements for lights can vary depending on the type and number of fixtures. As a general guideline, incandescent bulbs typically require around 40 to 100 watts, while energy-efficient LED bulbs can require around 5 to 20 watts.


The wattage requirements for electronics, such as televisions, computers, or gaming consoles, can vary. It is best to refer to the product manuals or specifications for accurate information on their power consumption.

Kitchen Appliances

Kitchen appliances, such as microwaves, toasters, or blenders, can require varying wattages depending on their size and power. Refer to the product manuals or specifications for accurate wattage information.

Washing Machine and Dryer

A washing machine can require around 1,200 to 2,400 starting watts and 500 to 1,200 running watts, while a dryer can require around 1,500 to 3,500 starting watts and 1,200 to 2,800 running watts.

Sump Pump

A sump pump typically requires around 800 to 2,500 starting watts and 500 to 1,500 running watts, depending on the size and power of the pump.

Water Heater

A water heater can require around 3,000 to 6,000 starting watts and 1,500 to 3,500 running watts, depending on the size and type of heater.

Factors Affecting Generator Size

Climate and Weather Conditions

The climate and weather conditions in your area can impact the choice of generator size. If you live in an area prone to extreme heat or cold, your air conditioning or heating systems may require more power to operate efficiently. Consider the average temperature fluctuations and select a generator that can meet the increased power demands during extreme weather conditions.

Efficiency of Appliances

The efficiency of your appliances and electronics can affect the overall power consumption. Energy-efficient appliances will require fewer watts to operate compared to older or less efficient models. When calculating your wattage requirements, take into account the energy efficiency ratings of your appliances to ensure an accurate estimation.

Size and Type of House

The size and type of your house can also impact the generator size needed. Larger houses with more circuits and appliances will require a larger generator to power the entire house. Similarly, houses with electric heating systems or multiple air conditioning units will have higher power demands, requiring a larger generator.

Budget Considerations

Your budget will also play a role in determining the generator size. Larger generators with higher wattage capacities will generally come with a higher price tag. It is important to consider your budget constraints and balance them with your power needs to find the right generator size that meets your requirements.

What Watt Generator Do I Need To Run My Whole House?

Choosing the Right Generator

Standby Generators

Standby generators are permanently installed units that are connected to your electrical system and have the ability to automatically power your entire house during a power outage. They are generally the most reliable and convenient option for whole house backup power.

Standby generators are available in various sizes and fuel options, allowing you to choose the one that best suits your power needs and preferences.

Portable Generators

Portable generators are a portable and versatile option for backup power. They are typically smaller in size and can be easily moved around as needed. Portable generators can be used to power a few selected appliances or electronics, making them a convenient option for smaller power requirements.

However, it is important to manage the power load and prioritize essential appliances and electronics when using a portable generator for whole house backup power.

Inverter Generators

Inverter generators are known for their quiet operation and fuel efficiency. They are generally more expensive compared to conventional generators but offer the advantage of producing cleaner and more stable power. Inverter generators are a good option for powering sensitive electronics or appliances that require stable power.

Dual Fuel Generators

Dual fuel generators offer the flexibility of using two different types of fuel, such as natural gas and propane. They can provide continuous power by automatically switching between the two fuel sources. Dual fuel generators offer the advantage of uninterrupted power supply, even if one fuel source becomes unavailable.

Sound Level and Noise Considerations

When choosing a generator, it is important to consider the sound level and noise produced during operation. Standby generators are typically quieter compared to portable generators, as they are located outside the house and have built-in noise reduction features.

If noise is a concern for you, look for generators with lower decibel levels and noise reduction features to ensure a quieter operation.

Professional Assessment and Guidance

Consulting with an Electrician

It is highly recommended to consult with a licensed electrician when determining the wattage requirements and choosing the right generator for your whole house backup power needs. An electrician will have the expertise and knowledge to accurately assess your electrical system, determine the load requirements, and install the generator and transfer switch correctly.

Working with Generator Stores

Generator stores specialize in providing and installing generators. They can help guide you through the selection process, provide information on different generator models and sizes, and offer professional advice based on your specific needs and budget.

Manufacturer Guidelines and Representatives

Manufacturers often provide helpful sizing guidelines and recommendations for their generators. It is recommended to refer to the manufacturer’s guidelines and specifications to ensure you choose the right generator size and model for your whole house backup power requirements. Additionally, manufacturer representatives can provide further assistance and answer any specific questions you may have.

Installation and Safety Considerations

Generator Placement

The placement of your generator is an important safety consideration. Generators should be installed outside the house in a well-ventilated area, away from doors, windows, and other openings. This will prevent the accumulation of fumes and ensure proper ventilation.

Generators should also be installed on a stable, level surface to prevent tipping or movement during operation.

Local Building Codes

When installing a whole house generator, it is important to comply with local building codes and regulations. Building codes may specify requirements for the installation, ventilation, and fuel storage of the generator. Always check with your local authorities or consult an electrician to ensure compliance with all applicable regulations.

Safety Precautions

Using and maintaining a generator safely is essential to prevent accidents or injuries. Follow these safety precautions:

  • Always read and follow the manufacturer’s instructions for your specific generator.
  • Never operate a generator indoors or in an enclosed space, as it can lead to carbon monoxide poisoning. Place the generator outside in a well-ventilated area.
  • Only use your generator outdoors in dry conditions, and never operate it in wet or damp locations.
  • Keep flammable materials away from the generator and maintain a safe distance to prevent fire hazards.
  • Avoid overloading the generator by exceeding its wattage capacity. Be mindful of the power demands of your appliances and electronics.
  • Use proper extension cords and ensure they are in good condition. Avoid using damaged or frayed cords, as they can pose a safety risk.
  • Regularly inspect and maintain your generator to ensure its proper functioning and safety.

Maintenance and Regular Inspections

Regular maintenance and inspections are crucial for the safe and efficient operation of your generator. Follow the manufacturer’s recommended maintenance schedule for tasks such as oil changes, filter replacements, and general inspections.

Regularly check the fuel supply and ensure it is clean and free from contaminants. It is also important to test your generator periodically to ensure it starts and operates correctly.

Budget Considerations and Financing Options

Generator Costs

Generator costs can vary depending on the size, brand, and features of the unit. Larger whole house generators will generally come with a higher price tag compared to smaller portable generators. Additional costs may include installation, permits, and any necessary electrical upgrades.

It is important to consider your budget when selecting a generator and factor in any additional costs associated with the installation and maintenance of the unit.

Installation Costs

The installation costs of a whole house generator will depend on various factors, such as the size of the generator, the complexity of the installation, and any necessary electrical upgrades.

It is recommended to obtain quotes from qualified electricians or generator stores to determine the installation costs and ensure they fit within your budget.

Financing and Loan Options

If the upfront costs of a whole house generator and its installation exceed your budget, there are financing and loan options available. Some manufacturers or generator stores may offer financing plans or partner with financial institutions to provide loan options for generator purchases.

It is important to carefully review the terms and conditions of any financing or loan options and consider the impact on your overall budget before making a decision.

Homeowner’s Insurance Coverage

When investing in a whole house generator, it is important to review your homeowner’s insurance policy to determine if any coverage is provided for the generator. Some policies may offer coverage for damage to the generator caused by incidents such as fire or theft.

Contact your insurance provider to understand the coverage details and ensure your generator is adequately protected.


Determining the wattage requirements and selecting the right generator for your whole house backup power needs is a crucial decision. By following the steps to calculate the required watts, considering important factors such as fuel options, climate conditions, and the efficiency of appliances, and seeking guidance from professionals, you can make an informed decision.

Remember to prioritize safety by following proper installation and maintenance procedures, complying with local building codes, and considering safety precautions during generator operation.

Take into account your budget and explore financing options if needed, as a whole house generator is an investment that provides peace of mind during power outages. With the right generator in place, you can ensure the uninterrupted operation of your essential appliances and electronics, keeping your household comfortable and functional even during unexpected power disruptions.

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