How Long Can A Whole House Generator Run?

During power outages, whole-house generators ensure an uninterrupted electricity supply for our homes. But the burning question is: How long can a whole house generator run?

If your generator uses natural gas as the source, it will run for an unlimited time as long as you provide it with fuel. With a full tank of gasoline, it will run for 8-12 hours. With propane for 48 hours and with diesel for 24-48 hours. However, with a continuous flow of fuel, a generator can run up to 3000 hours.

Let’s delve into the world of backup power and discover the secrets behind a whole-house generator’s operational longevity. 

Generator Runtime for Whole House According to Different Fuel Types

Generator Runtime for Whole House

Let’s consider that every factor that contributes to the generator’s runtime is normal. Now, let’s see how much run time you would get with different types of fuel –

  Types of Fuel  Runtime
  Using Natural Gas  Unlimited
  Using Gasoline  8-12 hours
  Using Propane  48 hours
  Using Diesel  24-48 hours

How Long Can a Gas Generator Run Continuously?

We typically hook up a natural gas generator to a continuous supply of natural gas with a utility line. So, it will run for an unlimited amount of time, until the gas runs out. 

In other words, as long as there is an uninterrupted natural gas supply, the generator will keep running.

How Long Can a Gasoline Generator Run Continuously?

On a full tank of gas, gas generators can run for 8-12 hours. In this case, the fuel efficiency of the generator is important. A more fuel-efficient generator will use less gas and run longer.

So, how long will a generator run on 5 gallons of gas?

A 500-watt gasoline generator at 25% load will last more than 290 hours on 5-gallon gas. That means, the runtime of the generator also depends on the load and the power of the generator. If there is more load and less power, a generator on 5-gallon gas may not even last an hour. 

But to find out exactly how long will a generator will run on 5 gallon gas, you need to consider many factors.

How Long Can a Propane Generator Run Continuously?

With a full propane tank, a propane generator can run for up to 48 hours. Usually, propane generators have a 100-pound tank. 

But how long will a whole-house generator run on 100 gallons of propane?

If your propane generator has a 100% load and 7kW capacity, it will last up to 66 hours with 100 gallons. A 12kW generator will last for around 36 hours. However, generators are usually used at 25% load, so the runtime will increase. 

Then, how long will a whole-house generator run on 250 gallons of propane?

Your generator will last more than 7 months on 250 gallons of propane if you use it normally without overloading it. But if you do decide to overload it, it may last up to a month.

Since your generator can run a long time with 200 gallons of propane, it’s a good fuel choice.

How Long Can a Diesel Generator Run Continuously?

It usually takes a diesel generator 24 to 48 hours to run on a full tank. However, this estimate is based on a moderate load and a typical fuel tank. The runtime may be shorter and require more frequent refueling if the power demand is higher or the fuel tank capacity is smaller.

Generator Runtime for Whole House According to Different Types of Generator?

how long can a whole home generator run

The run time of a whole-house generator can also vary based on the generator type. Here’s a breakdown of run times for different generator types.

Generator TypeEstimated Run Time 
PortableFew hours to 12-16 hours
StandbySeveral days to weeks
SolarSeveral hours to multiple days
InverterSeveral hours to 8-12 hours
HybridFew hours to several days
WindDependent on wind availability

How Long Can a Portable Generator Run Continuously?

A portable generator with a 5-gallon fuel tank and a moderate load may run for approximately 8 to 12 hours on a full tank. However, it’s important to note that these figures are approximate and can vary depending on the specific generator model, load requirements, and fuel type.

How Long Can a Standby Generator Run Continuously?

With a continuous fuel source, a standby generator can run for several days to weeks or even longer, as long as the fuel supply remains uninterrupted. The run time of a standby generator can vary based on the fuel supply and maintenance requirements

How Long Can an Inverter Generator Run Continuously?

While the run time of an inverter generator depends on various factors such as fuel capacity and load, it typically ranges from several hours to around 8-12 hours on a full tank of fuel.

How Long Can A Whole House Generator Run Continuously?

A whole house or a standby generator can continuously run up to 3000 hours if you provide it with the necessary fuel. But, it is not recommended to tune a generator continuously for more than 500 hours. 

But the run time of a generator will depend on various factors such as

  • Size of the generator: The larger the generator, the more power it can produce, and the longer it will be able to run continuously.
  • Type of fuel: Generators that use natural gas or propane can run for longer periods of time than generators that use gasoline.
  • Load: The more appliances and electronics that are being powered by the generator, the shorter the runtime will be.
  • Environmental conditions: Generators that are operating in hot or humid conditions will not be able to run for as long as generators that are operating in cooler or drier conditions.

How Can You Make Your Whole House Generator Runs Longer?

There are a few things you can do to make your whole house generator run longer:

  • Choose the right size generator: A generator that is too small will not be able to power your entire home, and it will overheat and shut down. A generator that is too large will waste fuel and money.
  • Choose a dual fuel generator: Dual fuel generators will provide longer runtime as you can switch between fuels. But be careful while choosing a dual-fuel generator.
  • Install a larger fuel tank: This will give you more runtime before you need to refuel.
  • Connect your generator to a transfer switch: This will allow you to switch your home’s electrical service from the grid to the generator without having to manually flip breakers.
  • Consider installing a backup battery: This will provide backup power for essential appliances, such as a refrigerator or sump pump, even if your generator runs out of fuel.
  • Maintain your generator regularly: This includes changing the oil, air filter, and spark plugs. Regular maintenance will help to keep your generator running smoothly and efficiently.

By following these tips, you can help to extend the lifespan of your whole house generator and keep your home powered during a power outage.


The question of “How long can a whole house generator run?” is crucial when it comes to ensuring a continuous power supply for your home. The answer depends on a number of factors, including the capacity of the generator, the load it powers, and the efficiency of the generator.

Frequently Asked Questions (FAQs):

Can a generator run 24 hours a day?

Yes, a generator can run 24 hours a day as long as it is properly maintained and supplied with fuel. Many generators are designed for continuous operation and can run nonstop for extended periods. 

Can you run a generator in the rain?

No, running a generator in the rain is generally not recommended. Water and moisture can pose a significant risk to both the generator and the people operating it. Water can damage electrical components, increase the risk of short circuits, and potentially cause electrocution. 

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