How Long Can You Run a Generator Continuously?

Imagine you are away from the power outlet, and you want to use some power tools for long hours, or there’s a power outage in your town courtesy of a storm, and you want to light your home. These are just some of the situations that might force you to use a generator. But how long can a generator serve you continuously? A generator is an important machine, but it can’t provide you with power as continuously as electricity. This is because it consumes fuel and is designed to run only for a specific number of hours. 

The question of how many hours a generator can run continuously doesn’t have a straightforward answer. This is because several factors affect the number of hours it can take running. These factors include: 

The size of the generator

The size of a generator is a crucial factor in determining how long it can take running. A small generator has a small fuel tank, meaning it will not last as long as a big generator with a bigger tank. So, if you want a longer run-time, you have to get a bigger generator. 

Stress level

Generator engines aren’t built like car engines. A car engine can run for a longer duration, while a generator engine will develop problems when stressed up. A generator’s life cycle gets affected by the level of stress it is subjected to. 

When overworked, it can overheat and develop other problems as well. Many generators will gradually start losing their power-generation capacity if allowed to run for over 24 hours. Meaning they have to be allowed to rest for them to perform optimally.

The area the generator covers

If you have a big house with several electrical appliances, a portable generator will be a big disappointment. 

A portable generator can not power so many electrical appliances at the same time and will not perform as expected if overloaded. Besides, it will not accommodate enough fuel to help it serve the appliances for a long duration. In short, the number of gadgets a generator serves will determine how long it will last. 

A bigger generator is needed to support many appliances, but that doesn’t mean it will run for many hours. The larger the area covered, the shorter the time it takes running. 


How Much Fuel Does a Portable Generator Use?

To understand how limited a generator is when it comes to running continuously, you need to understand the amount of fuel it consumes. Many generators use gasoline. Other fuels used by generators are diesel, natural gas, and propane. 

As stated above, the fuel consumption by a generator will depend on the stress level, the area it covers, and its power output. The rate at which the generator consumes fuel determines how long the generator will serve. 

On average, a big 5000-watt generator consumes about 2.3 – 3.0 liters of fuel per hour., while a small generator can consume about 0.8 – 1.0 liters per hour. It means the bigger generators consume between 55 to 72 liters of fuel in 24 hours, while the small ones consume between 19 – 24 liters of fuel in 24 hours.

Generators find application in many areas. You can use a generator during a camping trip, to keep your home lit during a blackout, or to power an outdoor activity where there’s no power outlet. 

Since generators are designed to provide power only for a short duration, long hours of power outages can pose a great challenge because it may force you to overwork your generator. This brings us back to the question of how long a generator can run continuously. 

As mentioned earlier, this question is difficult to answer, so we’ll look at different scenarios to help put everything into perspective. 

A portable Generator Using Gasoline

Most people are connected to the grid, meaning they only use generators in emergency cases. 

If your generator uses gasoline, the number of hours it will serve you is quite limited. This is because the generator is not supposed to be refueled while it is running. Topping up the fuel tank when the generator is running is a dangerous affair. When a generator is running, it gets very hot. 

When refueling a hot generator, the fuel fumes could spark, causing the gasoline tank or the generator itself to go up in flames. It means the number of hours your generator can take while running will depend on the size of its tank. 

Depending on your generator brand and the nature and number of appliances it is supporting, a portable gasoline generator can serve you for a maximum of 12 hours. If it is heavily loaded, it will only run for a few hours. There are some portable gasoline generators with large tanks that can last for more than 12 hours. 

For example, the Westinghouse WGen3600v generator can serve you for about 18 hours on a full tank. Before you buy a gasoline generator, check the specification, especially the fuel tank capacity, because this will help you determine how long it will serve you per full tank. 

A Portable Generator Using Propane

If your generator uses propane, you may have some control over the amount of fuel you can feed it in one run. A propane generator will offer you the option of keeping it continuously fueled. 

One way of doing this is by hooking two fuel tanks on the gas line using a changeover regulator or its stopcock valve. This way, you can let the generator run on the first tank while the second one is closed. 

When the first tank gets drained, you can let the generator use fuel from the second tank by twisting the control valve. In this case, the changeover regulator or the stopcock valve will allow you to replace the depleted tank with the full one without having to turn off the generator first. 

Suppose you have access to as much propane as you may need; how many hours can your propane generator run continuously? First of all, it is worth noting that a generator requires some form of maintenance after every 100 hours. 

Another factor that can limit the number of hours the generator will run is the quantity of oil in its engine. The oil usually requires to be topped up after 150 – 200 hours of generator use. 

Many modern generators will automatically shut down when the level of oil gets too low. This means it is not only the fuel that will determine how long the generator can run continuously but also the amount of oil in the engine. 

Another factor that can limit the number of hours your propane generator can run continuously is heat. During use, the generator will get hot. 

If the generator runs beyond its normal run-time, the heat build-up can lead to permanent damage to the generator. A generator will overheat when it runs continuously for over 12 – 24 hours. So even if you have enough fuel and oil, the heat may limit the number of hours the generator can serve you. 

If the generator is sunning in warm/hot weather, pack it with ice or use a fan to help cool its engine. This is a way of extending its run-time. Also, remember that running a generator to its full capacity will make it heat faster, so try to lower its output wattage if you want it to last longer. 

If you manage your propane generator well, it can run continuously for between 150 – 200 hours (6 – 8 days). 

Standby Generators

If you are cut off from a power source, and you need a generator that can serve you well for some days, a portable generator won’t be the best option. A standby generator would be your best option. 

These generators are larger and more efficient. Their motors are designed such that they can run for several days without showing any signs of fatigue. You can connect these generators directly to gas lines or big propane tanks (500 – 1000 gallons), which can allow them to run for days on end. 

However, the standby generator manufacturers don’t recommend using the generators for over 500 hours non-stop. These machines also get hot during use, and they also need oil. So, you should give them time to cool down or turn them off as you top up the oil. 

If you use the generators beyond the duration recommended by the manufacturers, you risk damaging them permanently, and it would be very costly to replace them. 

how long can a generator run

Different Situational Variations

Apart from the other factors, certain situations will affect how long can a generator will run. Some of the basic ones are –

Using One Gallon Gas 

It is dangerous to store gas in huge quantities no matter where. Gas is one of the common fuels for generators, but they are also quite expensive for large generators. However, they are a great choice for portable generators. 18 gallon of gas will run a 5k-watt generator for about 24 hours. However, the cost is most likely to hit the roof. The best option is to purchase an efficient gas generator that can easily run for about eight to ten hours with just a couple of gallons of gas.

Usually, one gallon of gas will run only for an hour. It is the reason why most people today prefer inverter generators that can last quite long. These are available in environmental-friendly modes, and their overall output and performance depend on the load needed.

Using Five Hundred Gallon Propane

Many people want to know about propane generators at home to identify how costly it is to run them. Propane generators are quite expensive, but they are highly desirable. They offer many huge benefits, but there are also certain drawbacks one has to deal with. Gasoline or diesel generators have higher efficacy than propane generators as they consume high amounts of fuel. Gasoline or diesel produces more energy than propane. A 5k-watt generator can run for about 920 hours without any issue with 500 gallons of propane.

Tips to Help Keep Your Generator Running for Longer

Keep your generator in the best condition to make sure that it can run for long when needed without issues. Here are some tips to help you achieve it –

  • For diesel and propane generators, it is best to have them connected to a large independent tank. If you have a gasoline generator, do not keep large amounts of fuel close to it.
  • If you have recently bought a generator, make sure to change the engine oil after every 100 hours of run time. If it is old, change it after 24 hours of use to keep it in good condition.
  • Always keep your generator clean with regular dusting and washing. Do not let dirt clog its ducts and vents, as it can damage the generator’s delicate parts.
  • Hire a professional for routine inspections of your generator for at least one year. They will check all the different parts of the generator to ensure it is in good condition. With the age of the generator, increase the frequency of inspections too.
  • Store it properly and keep it away from weather elements like direct sunlight or rain. In between run times, remove the fuel from it before storing. Also, remove the spark plug and put the recoil starter knob in neutral.
  • Always check the air filters and change them after every 100 hours of runtime or once a month.
  • Do not use old or stale fuel. Always use fresh fuel to extend the life of your generator and extend its run time.
  • Inspect your generator for leaks and seal them tightly. Leaks can reduce the efficiency of your generator and is a fire hazard.


What is the Average Running Time of a Generator?

Different generator models have different run times. While some can easily run for about eight hours without any problem, others can run for 12 hours and even more. It is important not to keep running it for a long period without giving it a break. The main reason for the much-needed rest is the way these generators are designed.

Just like any other machine, even the generator needs greasing, fueling, and maintenance. Before we go into the details of the different factors that affect how long your generator will run, it is important to know about the different types of generators and what type of fuel it uses.

What is a Generator Continuous Running Time?

A generator is a machine that converts mechanical energy to electric energy. We need a constant source of power for most of our everyday activities. In case there is a power outage, it is critical to have a generator handy that can power our house’s lighting, devices, etc. Here, we will answer some basic questions about generators –

How Long Does a Generator Run?

Generators have varied continuous running times based on the models, and there is no hard and fast rule to it. Different generators are designed to power different appliances for a few hours or days, depending on the type of generator they are. Most common generators can run in the range of about eight to twenty-four hours without the need of refueling or turning it off. Some high-end generators can run a little longer too.

No matter what type of generator you are using, you will need to give them some rest to allow them to cool down, lubricate, and refuel. It is not possible to run your generator without giving it some time to rest, and it can be dangerous too. So, make sure you check with the manufacturer’s guidelines and user manual to know how long the generator can run before it runs out of fuel.

Can a Generator Work as the Main Power Source?

No, generators are designed as an alternative source of power if there is a power outage or a power source is needed outdoors. Generators are meant to be used as a power-backup and cannot be used as a primary source of power. It is possible, though, in a very tiny setting with very limited and restricted power requirements. If you choose a generator as the main source of power, it will be costly.

And, you must be ready to spend on a new generator far too often than you anticipate. Leaving a generator on for long hours reduces its lifespan eventually and decreases its performance and efficiency. The good news is that there are generators with automatic turn-off switches that automatically turn off the machine when it runs out of fuel to prevent any internal damage. However, just because a generator has this feature doesn’t mean you should misuse it. Make sure to turn off the generator after it has run for a reasonable amount of time.

What are the Main Reasons Generators Do Not Last Long?

Since generators need regular maintenance, it is not advisable to run them continuously for long. Since these generators run using motors and need fuel, they need to cool down before adding more fuel. If you keep running them, they will eventually develop mechanical problems leading to engine problems. Even generators with a cooling system will not run for long and eventually fail if you try to run them without a break.

If you have to run your generator for a long time, make sure to follow the manufacturer’s user manual. Overlapping the guidelines provided for the specific generator model means attracting trouble for the machine. Proper maintenance and cleaning of the generation are essential to extend its life. It is also worth changing the spark plug once or twice a year to help ease the engine’s pressure, optimize its performance and increase the lifespan of your generator.

Is it Possible to Run Your Generator Overnight?

In many cases, you can easily leave your generator running overnight without any issues. But, it will depend on the runtime of your generator. A generator that cannot run for at least 8 hours won’t be enough to function the whole night. It is best to pick a generator with a runtime of at least 12 hours if you want to use it overnight. Also, keep in mind that just because a generator’s manufacturer claims it can run for 8 hours, it may not always be true.

Wrapping it Up

As you can see, the number of hours a generator can run continuously depends on several factors, including the type of the generator, its size, the stress level it gets exposed to, and the number of appliances it serves. 

Generators also get hot during use and need oiling, which are other important factors in determining their run-time. 

No matter the type of generator you are using and the number of hours you need the power, you have to give your generator time to rest. Always check the manufacturer’s specifications to guide you on how to use the generator.