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How Does how long generator last Work?

Feb. 04, 2024

A generator, be it portable or standby, need fuel to run. The common types of fuel are gasoline, propane, natural gas, and diesel. Apart from the one time cost of the generator, there is a recurring cost of fuel that you have to spend every time you want to use the generator. This is where the fuel efficiency of the generators become important. A popular question among generator owners is how long can generator run. This is of course subjective to the type and amount of fuel. Another time-related question is how long does a generator last. This question is applicable to know the lifetime of lifespan of a generator.

In this guide, we will see some basics of generators and answer these two questions i.e., how long can generator run and how long does a generator last.

A Brief Note on Generators

A backup generator is a device that provides electricity in the event of a power outage. Backup generators come in different types, each with unique features that make them suitable for specific applications.

The most popular ones for residential and small business applications are portable generators. These are small generators that are typically fueled by gasoline or propane.

As the name suggests, these generators are portable and you can move them around easily. Portable generators are also common for camping trips, outdoor events, and small power outages.

Inverter Generators are similar to portable generators but have some additional features. They produce clean, stable power that is safe for sensitive electronics like computers, audio equipment, smartphones, etc. They are also more fuel-efficient and quieter than traditional portable generators.

Standby generators are larger generators that we permanently install outside a home or business. We have to connect these generators to the residential (or a structure’s) electrical system

The benefit of standby generators is they automatically turn on when there is a power outage. Standby generators can power your entire home or business and are suitable for long-term power outages.

There are other types of generators such as Whole House Generators, Solar Generators, and Wind Turbine Generators but these generators are pretty niche.

Each type of backup generator has its own advantages and disadvantages, and the choice of which type to use depends on your specific needs and requirements.

Different Types of Fuels for Generators

We can run portable and standby generators with different types of fuels. The most common types of fuels for generators are:

Gasoline is a very popular fuel for small portable generators. It is widely available and easy to transport. But gasoline has a shorter shelf life compared to other types of fuels, and its use can produce emissions.

Diesel is a popular fuel for larger, stationary generators. Diesel generators are generally more fuel-efficient and have a longer lifespan than gasoline generators, but they can be more expensive to operate and maintain.

Propane is a clean-burning fuel that we often use for standby or portable backup generators. Propane generators are quieter and produce fewer emissions than gasoline or diesel generators, but they can be more expensive to operate and require a propane tank.

Natural gas is another popular fuel for large stationary generators, such as those units in commercial or industrial applications. Natural gas is often available through a utility line.

So, it is a convenient fuel source for these types of generators. Natural gas generators are quieter and produce fewer emissions than diesel generators, but they can be more expensive to purchase and install.

It is important to choose the right type of fuel for your generator based on your specific needs and the generator’s requirements.

How Long Can a Generator Run?

The length of time that a generator can run depends on several factors, such as the type of fuel it uses, the size of the fuel tank, and the generator’s load capacity.

Here are some general guidelines for how long a generator can run.

The type of fuel the generator uses will affect its runtime. Gasoline generators typically run for around 8 to 12 hours on a full tank, while diesel generators can run for 24 to 48 hours on a full tank.

Propane generators can run for up to 48 hours, depending on the size of the propane tank.

The size of the generator’s fuel tank will also affect its runtime. Larger fuel tanks will allow the generator to run for a longer period of time without the need for refueling.

The generator’s load capacity, or the amount of power it is providing, will also affect its runtime. If the generator is running at its maximum load capacity, it will use more fuel and run out of fuel faster than if it is running at a lower load capacity.

In general, a generator can run for several hours to several days depending on its fuel type, tank size, and load capacity.

It is important to have enough fuel on hand to keep the generator running for as long as necessary in the event of a power outage.

Gasoline Generator

The length of time a gas generator can run depends on several factors, including the size of the fuel tank, the generator’s fuel efficiency, and the generator’s load capacity.

In general, a gas generator can run for around 8 to 12 hours on a full tank of gas. The generator’s fuel efficiency can also affect its runtime. A more fuel-efficient generator will use less gas and run for a longer period of time.

To maximize the runtime of a gas generator, it is important to follow the manufacturer’s guidelines for proper operation and maintenance. This includes regular maintenance, such as changing the oil and air filter and monitoring the generator’s fuel consumption.

Propane Generator

Propane is a clean burning fuel and is slowly becoming a popular choice for portable generators. A propane generator can run for up to 48 hours on a full propane tank (100-pound tank).

However, this can vary depending on the generator’s size and how much power it is providing.

Diesel Generator

Diesel is a popular choice of fuel for large commercial generators. The size of the fuel tank in these generators is usually large. So, you can expect them to run continuously for longer periods.

In general, a diesel generator can run for around 24 to 48 hours on a full tank of diesel fuel.

Natural Gas Generator

A natural gas generator can run for an extended period of time because we typically connect it to a continuous supply of natural gas through a utility line. This means that as long as the natural gas supply remains uninterrupted, the generator can continue to run for as long as necessary.

The exact length of time a natural gas generator can run will depend on several factors, including the generator’s size and load capacity, as well as the availability and pressure of the natural gas supply.

However, in general, natural gas generators can run for days or even weeks without the need for refueling. It is important to note that natural gas generators require a connection to a natural gas line, which may not be available in all areas.

How to Improve Fuel Efficiency of Generators?

There are several ways to improve the fuel efficiency of generators i.e., make them run longer.

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Regular maintenance of the generator is important to keep it in good working condition. This includes cleaning or replacing air filters, changing oil and oil filters, checking spark plugs, and tuning the engine.

Running the generator at a load close to its rated capacity will ensure maximum fuel efficiency. Overloading the generator can cause it to consume more fuel than necessary.

Using high-quality fuel and fuel additives can improve fuel efficiency by cleaning the fuel system and improving combustion

AVR can maintain a constant voltage output and protect the generator from power fluctuations. This can improve fuel efficiency by reducing the load on the generator.

Using energy-efficient appliances with the generator can reduce the overall load on the generator and improve fuel efficiency.

Turning off the generator when not in use can save fuel and reduce emissions.

How Long Does a Generator Last?

The lifespan of a generator can vary widely depending on factors such as the type of generator, its usage, and the quality of maintenance it receives.

Higher-quality generators that are made with durable materials can last longer than lower-quality generators. If you use the generator frequently or for long periods, it may wear out faster than those with the less frequent operation.

Different types of fuel can have an impact on the lifespan of a generator. For example, diesel generators typically last longer than gasoline generators.

If you operate your generator in harsh conditions such as extreme temperatures or humidity, it may have a shorter lifespan than those used in more favorable conditions.

Proper maintenance, including regular oil changes, air filter replacements, and other routine checks, can help extend the lifespan of a generator. Running a generator at or near its maximum load capacity for extended periods can put additional stress on the generator and shorten its lifespan.

Proper installation and storage of the generator, including protecting it from moisture and ensuring proper ventilation, can help extend its lifespan.

By paying attention to these factors and taking steps to properly maintain and use the generator, you can maximize its lifespan.

In general, a well-maintained portable generator can last for around 1,000 to 2,000 hours of use, which can translate to around 10 to 15 years of use with regular maintenance.

On the other hand, a well-maintained standby generator can last for upwards of 20,000 to 30,000 hours of use, which can translate to 20 to 30 years of use or more.

How to Improve the Lifespan of Generators?

Here are some tips to improve the lifespan of generators.

Follow the manufacturer’s guidelines for maintenance, which typically include changing the oil and air filter, inspecting the spark plug, and checking the fuel system for leaks and damage.

Regular maintenance can help identify and fix problems before they become more serious.

Store the generator in a dry, clean area protected from external elements, and follow the manufacturer’s recommendations for long-term storage.

If you are not using the generator for an extended period, it is important to store it properly. This includes draining the fuel tank and carburetor, and storing it in a dry, cool place.

Use high-quality fuel that the manufacturer recommends reducing the likelihood of engine damage and wear.

Avoid overloading the generator and running it at its maximum capacity for extended periods. This can cause undue stress on the engine and shorten its lifespan.

Allow the generator to cool down before shutting it off and storing it. Have a licensed professional install the generator to ensure it is set up properly and safely.

Keep the generator away from harsh environmental conditions such as extreme temperatures, humidity, or rain. Try to balance the load across different circuits and reduce the load on the generator where possible.

By following these tips, you can help extend the lifespan of your generator and ensure that it remains reliable when you need it most.


Generators are mechanical device that contain an internal combustion engine. One of the main specifications of a portable or standby generator is the type of fuel it takes.

If you are buying a generator to use it continuously, then you also need to thing about the fuel efficiency of the generator as fuel is an on-going cost.

In this guide, we saw some generic answers to the question “How long can generator run?”. After that, we looked at the average lifespan of portable and standby generator by answering the “How long does a generator last?” question.

We hope that this guide could help you understand how long can generator run and also how long does a generator last. If you feel we missed something or want us to add anything, do let us know in the comments section below. It will help not only us but also other readers.

When to know it is time to replace your Standby Generator

As with any piece of mechanical equipment, standby generators are subject to wear, tear, and breakdown. But if after a few decades your generator isn’t having outward or obvious signs of degradation, when should you purchase a replacement? In this article we will go over six signs that may indicate it is time to replace your generator.

1. It Has Been In Service for a Long Time

Depending on the quality and size of your standby generator, most manufacturers usually predict that a standby generator will remain reliable anywhere from 10,000 – 30,000 running hours (about 25 – 40 years) depending on how well it is maintained. If maintained properly, the less you use your generator, the longer it will last. Even if it seems like your generator is still running strong after 40 years of light use, there are likely unseen internal parts that are well worn down and on the verge of breaking, you won’t be producing the same amount and quality of power that you were when the generator was first installed, and a critical failure may be right around the corner.

2. It Is No Longer the Correct Size for Your Needs

With any new business or home, predicting load growth is a tricky process. You could begin your business or move into a new home with one set of power needs, and then things could quickly evolve into a whole new set of circumstances. Whether your home or business is shrinking or growing, you need to be aware of the load being transferred to your generator when utility power fails. If your generator is too big for your load, carbon deposits could be building up in your gen without you even noticing. If this continues to occur for too long without intervention, your generators’ power producing capabilities will be greatly reduced. If your generator is too small for your load, the generator is more likely to fail or even overheat when power is transferred.

Revisiting your power producing requirements is a good idea, at least every time your power needs change within your home or business. If you notice your generator is not properly sized for your requirements, replacing your generator with a properly sized one is recommended for optimal power production.

3. It is Showing Signs of Wear

Even with proper maintenance and storage, wear and tear is a natural part of any machines’ lifespan. If you have not been performing routine maintenance or if your generator is exposed to the elements, wear will occur much faster, thereby shortening the lifespan of your generator significantly. Biannual maintenance and continuous sheltering of your generator from weather, dust, and debris can greatly increase the amount of time your generator will remain a reliable source of backup power for your home or business. If any part of your generator starts showing signs of excessive rust, it is time for a new generator.

4. It is No Longer Reliable

If your generator develops problems starting on demand or you notice you are calling the repair man more than normal; it’s time to buy a new generator. The main reason you purchase a standby generator is to provide backup power during a utility outage, so if your generator has problems starting during an outage, there is no way to know if you can rely on the power to be provided when you are not there to remedy any issues with starting.

5. It Uses Outdated Technology

Technology is ever evolving and things are upgrading at an increasingly rapid speed. What was state of the art ten years ago, is now outdated and seems like it was invented in the Stone Age. Generators are finely tuned machines that will only get more intricate and tech heavy as time goes on. If your generator is no longer supported by the manufacturer, or the technology is no longer able to be updated for your specific model; that may be a good indication that it is time for an upgrade.

6. Updated Ecological Interests

Air quality regulations are ever changing, and trending toward becoming more strict. With climate change happening at an ever increasing rate, our government has increased the laws surrounding diesel and natural gas generators. As generators age, they start to consume excessive fuel and have high levels of carbon monoxide output which, according to scientific research, is detrimental to the environment. If you start to notice either of these symptoms beginning to emerge, chances are your generator is not up to date with the current environmental standards for power generation equipment and should be replaced.

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Conrad has over 10 years of experience in power generation. He graduated from Universal Technical Institute, and has a master certification from Generac. He loves the great outdoors and spending his time camping and fishing.

How Does how long generator last Work?

6 Signs it’s Time to Replace Your Standby Generator

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