What Size Generator Do You Need to Run a House? [Guide]

It’s vital to have a little know-how of electrical knowledge as it saves you from potential heavy losses and you can do some basic repairs at home by yourself.

Knowing a bit about your home wiring makes it simpler to change faulty or old electric outlet, and it also prevents any accident and enhances your electrical safety.

When it comes to generators, some frequently asked questions are: What wattage generator do I need?

What size generator do I need for my home?

How large a generator do I need? Or what size generator to run a house?

If you are looking for an appropriate generator size for your house, you should lookout for a generator that gives sufficient wattage to simultaneously run multiple electrical appliances. Another that can help here is the generator size chart. When buying a generator, you can easily figure out what size generator you need for your house by reviewing the generator size chart.

For most homeowners, large 12,000-watt units are the safest option. For campers and RV, a standard 3000-watt inverter generator is perfect for basic appliances such as TV, AC, lighting, and fridge.

How to Calculate What Size Generator Is Needed to Power a House?

Firstly, always measure in watts (W). For your information, people often ask about a 3000-watt generator, and what will it run? Keep in mind that all generators offering between 1,000 to 3,000W are suitable for RVs and camping purposes, whereas you need heavy-duty generators to run the entire house starting from 9000W to above.

To determine what size generator is enough to run a house depends on your needs, and you must evaluate your power consumption and needs.

List down all the devices that you want to run.

Think about the appliances that are essential for daily household use, and you will use them during an emergency power outage when buying a generator to run the house; these appliances can be your AC, refrigerator, and lighting circuits.

Determine generator size for your house by a requirement calculator.

Take note of the following details:

Starting watts: it is an amount of electricity needed to start the appliance.

Running watts: it is an amount of electricity required to run after the appliance are started.

Choose a generator to run your house above your requirements.

It helps, and some of the reasons are given below:

A few hundred additional watts will always be available to consume.

The generator’s working life is not significantly reduced (as the generator will not work at full capacity)

Reduce generator’s noise (using it at full load makes it too much noisy)

What size generator do I need for my house calculator?

How big a generator you need relies on your actual power consumption. Suppose it is 1600 running watts; you should look for the unit that delivers at least 1800 wattage.

Similarly, try to buy a generator with 7500 rated watts and starting watts of 9500 if the maximum running wattage of your home electrical appliances are 7000 and the starting wattage is up to 8400. These few extra watts can be a major difference!

With an average generator giving rated watts around 5,000 to 7,500 watts, you can easily run normal household appliances such as refrigerators, well pump, TV, and lighting circuits. An adequate 7500-running watt generator can operate all these simultaneously.

For camping or RV, you need a 3000-4000-watt generator.

Though, to determine what size generator is needed to run a house, you should also list and know the precise wattage of your electrical appliances. Usually, you will find all these details on the labels measured in watts or amps.

Before buying any generator, you must ask yourself this question: Do you need the generator to run only the crucial equipment, or you want to power your entire house?

Well, you can answer this question in a much better way, but if you are living in a disaster-prone place where you often face power outage, then you need a larger generator to run the house. Regardless of its price, it will be a wise investment for you.

However, suppose you plan to use your new generator only a couple of times or in an emergency or on outdoor trips. In that case, a portable generator is fully capable of running the vital equipment.

What size emergency generator?

Mainly it depends on your exact needs, but a portable generator delivering between 3000 to 4000 watts is more than enough for emergency uses and to power basic home appliances.

Amps vs. Watts vs. Volts

Watts (W) and amperes (Amps) (A) are entirely two different units used to determine the total energy that electric appliances generate or consume. As for volts (V), almost all appliances in the US work on 120V. However, some appliances run at 220V. Determining how many amps an electrical appliance requires to work is simple: Wattage= Amps x 120


A 120V Electric Kettle with 70 Amps. 70A x 120V = 8400W Do you get it; what size generator to run the kettle, in this case. The answer is, you will need a unit that offers 8,400 running watts to power your electric kettle. Calculating the amperage (Amps) is also simple: Amps = Wattage / Voltage

Generator to run heavy modern appliances:

Traditional heavy-duty generators have a high Total Harmonic Distortion (THD). A THD of up to 3% is a safe and maximum threshold for most modern-day electronics. All grid generators work below this THD threshold, but not typical heavy-duty generators. So, there is a chance that if you use modern appliances like flat-screen LEDs or refrigerators on a heavy-duty generator for too long, they will get damaged.


Always remember that if you are planning to use a portable generator, whether it is a heavy-duty or an inverter, never run it without a transfer control. It can help to prevent damaging your electric appliances and the electric grid as well. By now, we hope that now understand what size generator to run a house? Didn’t you?

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