How Many KW Generator Do I Need? This Calculation Will Help You

by Johnathan Roos
Last Updated on

A common question to ask yourself when buying a generator is “how many kilowatts, or kW, do I need?” This question refers to the size required for a generator to run power to your devices. In this article, we will discuss how you can calculate the power requirement of your house or office and buy the right generator to match.

What is a kW?

kW is the short form of a kilowatt, and it means 1000 watts. If your generator produces a total of 1000 watts every hour, it can be rated as 1 kWh, or 1 kilowatt hour. While most household appliances do not use entire kilowatts, it is a good idea to have a generator that does so that you can run all your appliances with a single device.

How to Calculate the Total kW of Your Devices

Using multiple methods, you can calculate the total power consumption of your house. After completing these calculations, you will get a single value in kilowatts so that you can buy a generator accordingly.

Keep in mind that finding the right size generator for your house or office depends on a number of factors. For starters, you have to consider how much backup power you will need in case of a power outage. You will also want to consider whether you are looking for a standby generator or one that operates on natural gas.

Now, let’s discuss the different ways calculate the power requirement of your house:

Method 1 – Watt Calculation

Check the labels of your appliances. Look for information such as input/output voltage, current consumption, and wattage. You can also find this information from the owner’s manual of the device, which you may also be able to look up online. There are also many sources on the internet to tell you the general wattage of common household items.

Once you’ve identified the watt consumption per device, you’ll need to calculate total kWh for each device by taking the hourly watt consumption multiplied by total hours of use. For example, if a device uses 300 watts per hour and you run it for 5 hours a day, multiplying both numbers will give you 1500 watt-hours or 1.5 kWh per day consumption. You’ll need to calculate daily consumption for each device you want to power to get the total daily wattage consumption amount you’ll need to cover.

Method 2 – Amp calculation

If you don’t see any label or can’t get the information listed above, look at the amps rating on the device. This rating should show how many amps your device consumes.

Next, multiply the amp-count and voltage to get the watts. For a default, the standard output voltage for most countries is 120V.  As an example, if your device has a label with 6.5 amps and 120 volts, you’ll multiple 6.5 by 120 to calculate that the device consumes 780 watts per hour.

Method 3 – Power Meter

Use a power meter. Connect the meter to your device, plug it in a wall outlet, and it will show you the power consumption rating of the device. This will be an accurate way to know watt consumption, but is less efficient if you need to figure out consumption rates for many devices.

What Size Generator Do I Need using Peak and Running kW?

How Many KW Generator Do I Need

If you have already measured and calculated the total power consumption of your house, 80% of your task is done. The total consumption you calculated is a base amount of power you’ll want to have covered with your generator.

Here are some other factors to consider when choosing which generator size is ideal for your home.

Peak kW:

Some appliances, such as refrigerators, air conditions, and water pumps require more power to start than to run. For example, a water pump can run on 300 watts per hour, but the generator will need to provide 1100 watts at the beginning. You’ll want to make sure your generator has enough power to start the device and not just run it.

Running kW:

You can follow one of the three methods mentioned above to find out the running wattage count of your home or office appliance.

Regardless of peak kW or Running kW, a general rule of thumb is to choose a generator that supplies power beyond your needs. Remember, larger generators generally produce more power, so the more power you need, you may need to make a bigger investment. In general, you’ll want to purchase a generator that has power coverage well over the total estimate of your home’s power requirement.

Final Steps

If you want a generator for the whole house or office, calculate the power consumption of all major appliances and make an estimate, rounding up to leave extra coverage over the final amount. Calculating all the items can take a lot of time, so we recommend writing down your calculations so you only need to complete the process once. .

For running a selected number of devices, you need to make a list and separately check their power consumption. For example, say you want to use a freezer, water pump, and a TV. 1280 starting wattage with 400 running wattage, 1100 starting wattage with 300 running wattage, and 200 running wattage are the power rating of the devices.

For such requirements, you can buy a 2000W or 2 kW generator, and start the items one by one. Starting all of them at the same time is not recommended due to their start up consumption, but you can take advantage of their lower running wattage to power everything with a 2 kW generator.

Frequently Asked Questions

Below are some answers to the most frequently asked questions.

What can a 100-kW generator power?

To understand if a 100-kW generator will meet your needs, see the specifications of the appliance that you want to run and see its starting power rating. If it matches your generator’s rating, you can power that appliances or piece of equipment. Ultimately, what devices a generator can power will depend on the devices themselves and how much power they require.

What can a 2 kW generator run?

A 2 kW or 2000-watt generator can generally run a 500-watt deep freezer, 650-watt microwave, a few lights, or something similar. This size generator is perfect for camping or running small home appliances that don’t need an initial voltage spike to start.

Will a 20kW generator run my house?

A 20-kW generator can power some but not all appliances in your home, depending on total size and number of appliances and how much power they all require.

How many kW is required for a house?

Generally, a mid-sized home can use a 20-kW generator to meet the emergency situations, or a 100-kW generator to provide full coverage for as long as you want.

Final Thoughts

Most homeowners choose to leave these concerns to their electricians. When it comes down to it, jobs such as installation and maintenance are best left to the professionals. That being said, you should still be knowledgeable about the topics at hand. Knowing your household power requirement is something that all homeowners should look into. With the easy-to-follow steps described above, you can easily calculate your home’s power requirement, getting you one step closer to understanding your household’s potential generator power needs.

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