How Long Can a Whole House Generator Run Continuously?

A typical whole-house generator can serve you continuously for up to 21 days. However, several factors determine how long a whole-house generator can last, including the quality of the generator, how well it is maintained, and the amount of fuel flowing into its tank.

Whole-house generators are the most common home backup power sources, and buyers often ask, “how long can the generator run continuously?”. A high-quality brand generator can run for several hours, but that largely depends on how you operate and take care of it. In this article, you will learn about factors that affect a generator’s runtime and what you can do to make your whole-house generator last longer.

Let’s dive in!

What Influences How Long a Whole House Generator Will Run?

Electricity Load

How long your whole-house generator will run is directly influenced by the workload on the generator. This includes the size of your house and electrical appliances and the amount of power they consume. Tools like refrigerators, water heaters, and sump pumps consume the highest power. When buying a whole-house generator, go for one that will sufficiently power your whole house and its peripherals.

You can determine the perfect fit by calculating the total wattage of all your electrical appliances by at least 1.5. This will create an adequate margin of safety, so you don’t overpower your generator.


The amount and type of energy or fuel also directly affect how long your whole-house generator will run. A generator with little or no fuel will not run. Your generator will operate to its maximum runtime if there’s a continuous fuel supply.

The most common types of energy used in whole-house generators are propane and natural gas. This is because they leave a minimum carbon footprint and don’t become stale over time. Propane gives you some control as you can continuously supply it to your generator to prolong its runtime. A generator fueled by propane can continuously run for up to 500 hours.


Every whole-house generator needs oil to run smoothly and prevent it from overheating. A generator with little or overused oil will not operate properly. Most whole-house generators are designed to shut off when the oil level reduces automatically. You are advised to check your generator oil regularly and change it, especially after running the engine for many hours.


Your generator’s runtime is affected by the generator itself. How big is it? What brand is it? Does it produce enough power? All these are factors to consider when shopping for a whole-house generator. Typically, the generators are designed with higher output since their job is to power higher loads. In case of a blackout, they can power most of your home’s utilities for long periods without issues.

How to Make a Whole House generator Last Longer

A whole-house generator is a valuable asset that does not come cheap. If you want the generator to serve you properly for a long time, you want to ensure that you’re at least doing everything right in terms of use and maintenance.

One way to do it is by operating the generator properly. Usually, generators have the exact working mechanism, but their operation may vary depending on the brand and their unique components. Check the generator manual for instructions if it’s your first time owning a generator. And if something is unclear, call the manufacturer to avoid causing problems.

Another simple way to make a whole-house generator run longer is through regular servicing and maintenance. The engine is a delicate component that requires constant monitoring and care. You must ensure that it is running on enough fuel and oil at all times and that the oil is not overused. Most brands recommend changing the oil after about 100 hours of use to be safe. Pay for professional servicing at least twice a year. This will ensure the generator runs smoothly and help you curb any potential problems.

Thirdly, don’t overwork your generator. Every unit comes with a stated maximum capacity. Loading it beyond its capacity can lead to excessive heat, which will cause the unit to explode. If your electricity requirements are high, you’re advised to get an overload protection device that switches off your generator whenever it’s overloaded.

Best Whole House Generators that Last

Unit How long they last Continuously
Westinghouse WGen1200 This generator is the best overall for home use. It is a high-quality unit that can run continuously for 16 hours on a 10.5-gallon tank.
Champion 14-kW aXis Home Standby Generator This is the best unit for a heavy-duty home. It offers a total of 14,000 watts, enough to light your home and power your tools. On a full tank, it can run continuously for 10 days.
Generac Guardian Wi-Fi-Enabled Standby Generator This is the best smart generator that can be connected to your phone or computer for monitoring. It can run continuously for up to 72 hours on liquid propane or natural gas.
Generac 7,500 Watt Standby Generator This power-pact is best for small homes that require few watts of power. It can power up to 8 circuits in your home and provides 16 hours of runtime at half-load.


Overall, your whole-house generator’s runtime depends on the type and size of the generator, your electricity load, the fuel you use, and how well you oil it. Do note that each generator has a recommended limit, which can be about 200-500 hours on average. If you want your generator to run smoothly and continuously, maintain it properly and have it professionally serviced at least twice a year.


How long will it take to install a new whole-house generator?

Installing a whole-house generator takes weeks, sometimes months, depending on its availability, your chosen contractor, and the permits needed. However, when all is done, you will have peace of mind knowing you have a great asset that can power your home during a power outage.

Is a whole-house generator noisy?

Yes, it is. But it is less noisy than a portable generator. A whole-house generator emits between 60-80dBA of noise. However, how loud it is will highly depend on its closeness to your house.

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