How Long Can You Run a Generator Continuously

Generators are a vital piece of equipment in many homes and businesses. They provide power for running essential home appliances in case of a blackout, lighting camps and powering tailgating activities and, meeting your power demands at a worksite. Ideally, the purpose of a generator is to provide temporary power, but you may have to push it beyond its limit when there is an extended blackout. So, how long can you run a generator continuously?

Several factors determine how long your generator will run continuously. These factors include the size of the generator, fuel source, type, and brand of the generator. Read on to learn more about how long you can run your generator.


What to Consider When Determining the Continuous Runtime of Your Generator

Generators come with different properties which influence their runtime, capabilities, and their efficiency too. Here are vital factors to look at when determining how long your generator can run continuously.

Size of The Generator

The size of your generator is one crucial factor that determines its capability to provide power continuously for a more extended period. More giant generators can produce more wattage than smaller ones. And this means they are capable of running appliances at home or powering larger machines at home or in commercial settings for a longer duration.

Their big fuel tank capacities support their long runtime. A big generator model has a bigger fuel tank capacity than a small generator. For instance, standby generators have bigger fuel storage tanks than portable generators.


Type of Generator

The type and brand of the generator also determine how long you can run it continuously. For instance, standby generator models are made to run for longer hours than portable models. Their engines are efficient and can run on diesel, natural gas, or propane gas. Standby models running on natural gas can be connected to domestic natural gas lines or massive propane storage containers to run for a longer period. They can offer an extended runtime of about 14 to 21 days nonstop. A big advantage of using standby generators is running for long hours.

Their fuel tank capacities contribute to the differences in runtime between standby and portable generators. The bigger the fuel tank, the more extended runtime the generator will offer.

Inverter generators have a longer runtime compared to conventional models. This is because inverter models have high fuel efficiency compared to conventional generators.

Fuel Source

There are three common fuel sources for generators:

  • Gasoline: Most portable generators use gas as their source of fuel. Gasoline-powered generators cannot run continuously for an extended time, and you have to shut them down from time to time and refuel.  You must not refuel a gasoline generator when it is running. With the hot surfaces of a running generator, any gasoline spillage on the surfaces can lead to a fire outbreak.


Propane-powered cannot run continuously; instead, their runtime is determined by the size of their fuel tank and how much power you’ll be drawing. The standard runtime for most gasoline generators ranges from 6 to 12 hours. However, models like Westinghouse WGen3600v can achieve a runtime of 18 hours on a single tank.

  • Propane: Generators that run on propane are continuously becoming popular. Propane-powered generators allow you to control the fuel tank, which offers an opportunity to keep the generator running for long hours if you can keep it fueled for long.


You can extend the runtime of a propane-powered generator by connecting two propane tanks into a single gas line using a stopcock valve. With such a connection, propane can flow from one tank to the generator while the other is on standby. You can switch to the other tank by changing the stopcock valve once the first tank is consumed up. You can proceed to replace the consumed propane tank with a new one so that you will not run out of fuel. That way, you can extend the runtime of your generator.


  • Diesel: Most diesel-powered generators have a 24-hour tank. However, you can also use diesel generators with a runtime of 48 to 72 hours. Just like a gasoline generator, you need to power off the diesel generator, allow it to cool down before refueling it. Therefore, diesel generators cannot run continuously without being shut down for refueling.

Most standby generators run on diesel.

Fuel Consumption

How Long Can You Run a Generator ContinuouslyA generator with a high fuel consumption rate will run for a shorter period than one with low fuel consumption. It explains why generators with low fuel consumption rates can run longer than traditional models, like inverter generator models.

Other factors affecting how long a generator can run include:

  • Oil level: Modern generators will auto shut down when the oil level goes below a specific level. If your generator has a small oil capacity, its runtime will be low than one with a bigger oil capacity. Always check the oil level of your generator before running it.
  • Carrying load: A generator running at a quarter load will run for longer than one running at 100% load.


How to Estimate the Runtime of a Generator

Coming up with a precise answer on how long you can run a generator continuously can be difficult because of the several factors influencing the runtime. With the runtime of gasoline, diesel, and propane generators being different, you can always estimate them.


Divide the fuel capacity of the generator by its consumption rate. Your generator vendor should be able to give you the generator’s fuel tank capacity and its consumption rate. If this information is not available, you can estimate the figures by comparing the generator to a similar generator size from another company. This may not give you an accurate answer, but it will give you an idea of how long the generator can run continuously.


In different scenarios, the generator dealer may make it easier for you by giving you the generator’s expected runtime, saving you time for calculation.


So, how long can you run a generator continuously?

Portable generators running on gasoline can run continuously for about 12 to 18 hours on a single tank. However, if you use a propane-powered generator connected to a large propane gas tank, the runtime can increase to 5 to 8 days. However, this runtime may be limited by the mechanical features of your generator, including engine oil. Hooking up a large generator to a domestic gas line will offer you 500 hours of continuous power supply from the generator.


Tips for Maintaining Your Generator


Generators are an excellent addition to your home or business, but they can’t work without proper care and maintenance. Here is how you can make the most of your generator.

  • Routinely run the generator at least once a month when it’s not in use. Doing this will keep the battery fresh and charged and keep the generator ready for the storm.
  • Drain out any fuel in the generator before storing it for long periods. This will prevent staling of fuel in the tank. You should also avoid using substandard fuel or poor-quality fuel on your generator.
  • Inspect and clean or replace the air filter after every 25 hours of continuous operations. The air filter traps dirt and dust particles that can hamper the performance of your generator.
  • Inspect the spark plugs at least once in six months. A bad spark plug will make it challenging to start your generator. If the plug is marred up, use a wire brush to clean it. If it is worn out or damaged, you will need to replace it. IN most cases, if your generator’s air filter is dirty and needs a replacement, you should also consider replacing the spark plug.
  • Check the fuel lines, wire connections, and terminals for signs of corrosion or loose wiring before using your generator in emergencies.


Frequently Asked Questions

How many hours straight can you run a generator?

Generators like Westinghouse WGen3600v can achieve a runtime of about 18 hours nonstop while others achieve 16 hours of runtime. Standby generators can run for up to 21 days nonstop. How long a generator can run continuously depends on the type and size of the generator, fuel source, and loading capacity.

How long can a whole house generator run continuously?

A generator should run as long as it has sufficient fuel and oil levels. For instance, when using a large propane tank as your fuel source, a whole house generator can run for 5 to 8 days. However, achieving such a runtime can be hindered by the engine oil level of the generator. A large standby generator connected to a gas line can run for around 500 hours nonstop.

How long can a Generac generator run nonstop?

The runtime will depend on the load on the generator. For instance, a portable Generac generator with a 50% load will run for 10 hours continuously on a single tank. If you use a more powerful Generac generator, you can achieve a runtime of 30 hours nonstop with the same load.

Can you run a house on a generator full-time?

How Long Can You Run a Generator ContinuouslyYes, however, this may turn out to be expensive on your side than paying for your utility bills. Besides the fuel costs, you will incur frequent costs of servicing the generator and parts replacement. Additionally, running the generator nonstop can lead to overheating of the engine components, which can damage and reduce the generator’s lifespan. Therefore, it is not advisable to run your generator for 24 hours a day.

How long do generators last?

Depending on how much load the generator will carry and the model, most portable generators are made to last between 10,000 and 20,000 running hours. Therefore, if your generator usage is about 500 hours annually, your generator may last 20 to 40 years, provided you follow a proper maintenance schedule. If you are a frequent generator user, the generator will last for a few years.

Are there generators that can run for 24 hours nonstop?

How Long Can You Run a Generator ContinuouslyYes, standby generators can run for 24 hours or more continuously. Such models are made to run for longer hours, and they use propane or natural gas as their fuel source. Running such generators on gas will turn out to be very expensive.

Most portable generators cannot run for 24 hours nonstop. This is because of their small fuel tank.

Is it cheaper to run your house on a generator?

It is cheaper to run a house on the grid power than the cost of running a generator every day. It is expensive to run a generator daily because you have to cater for the fuel costs, repairs, and maintenance which you can avoid by using grid power. Furthermore, generators are efficient when used as temporary power solutions and not a permanent solution.

How long will a 20lb propane tank last on a generator?

How long a generator can operate will depend on its load. On average, a propane-powered generator will consume two to three pounds of propane per hour. Thus, a generator can operate for about five hours when running on a 20lb propane tank.

Should you turn off the main breaker when running a generator?

Yes, you must switch off the main breaker before connecting your home with the generator power. If you fail to do this, you may send power to the mains line, which can be dangerous to the servicemen working on the utility line.


Final Word

How long a generator can run continuously depends on the type, size of the generator, fuel source, and loading capacity. Most portable gasoline generators can continuously run for 8 to 12 hours at 50% load on a single tank. On the other hand, diesel standby generators can run continuously for 500 hours or more depending on the load. Portable and standby generators have different power output and fuel tank capacities, explaining why they differ in running time. If you are looking for a generator to power your house for long hours continuously, you should consider standby generators. They are designed to operate for long hours, and they are fuel-efficient and require minimal maintenance.


About Steve Stuart

Steve Stuart is an electrical engineer who developed interest on generators during his school years. After school, he became a generator enthusiast. This is after encountering power supply problems at the area of residence where he lived. Power would be on and off and so food would go bad and the room heater would go off especially during winter. After trying the different generator brands for several years, Steve now provides information on the available brands and products in the market today. Based on his experience, he gives the do’s and the don’ts when it comes to generator use.

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