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How Long Will a Generator Run on Propane?

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Incredibly versatile, generators can be used for many different purposes. They can be used to light up a camping trip, power an outdoor party, or even keep your home running in the event of an emergency.

Most of the time, you won't have to run the generator for more than a few hours at a time, but in the event of protracted power outages especially during extreme weather, you may have to run it hard.

How Long Will a Generator Run on Propane?

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If you need to operate your generator but don't know how much propane you'll need, here's a simple approach you can use to estimate how much you'll need:

Gallons of propane used per hour can be calculated as follows: Watts eg 3000 x 0.65.

This is for a 3000 watt generator. Let's dissect this approach to see how it can be used to calculate your total propane consumption.

Step 1

Let's establish some baseline assumptions about the typical generator with the help of the below data before we get started.

On average, a two horsepower generator will generate one thousand watts. The second point is that you need 10,000 BTUs of fuel to generate just one horsepower. Each gallon of propane weighs 4.2 pounds and has a fuel value of 92,000 BTU.

So we will need to use those assumptions in our calculations. 

Step 2

Now, we need to figure out how many horsepower we're actually utilizing.

To convert watts to horsepower, (watts/1000)*2

A 3000 watt generator would require a total of 6 horsepower.

Step 3

So, we can get the BTU ratio we need by plugging our calculated horsepower into this formula:

BTU is horsepower*10000

In the end, we were only able to generate 6 horsepower during the second phase. If we add this to the equation in the previous sentence, we get an hourly output of 60000 BTU.

Step 4

Finally, the amount of propane produced can be calculated as follows: BTU/92000

Let's factor in the 60000 BTU we determined in step three. Last but not least, it can be seen that running a 3000 watt generator 24 hours a day will use 0.65 gallons of propane.

The above formula is the result of plugging all of the data into a single equation. Because of this, 0.65 gallons of propane weighs roughly 2.73 pounds. To get there, take the 0.65-pound weight of one gallon of propane and multiply it by 4.2 to get your answer.

A 20-pound propane tank has a total capacity of 4.76 gallons, as we shall now demonstrate using the following computation. Multiplying 20 by the result of (2.73 x 0.65) gives 4.76 gallons. We can extrapolate that a generator with a total load wattage of 3000 will run for 7.32 hours given this data.

The calculations are not linear, so a 6000W generator will not use double the propane as a 3000W, so you will need to do the calculations for every generator you have.

Again, keep in mind that these are just rough estimates based on the typical generator and don't properly account for the many different kinds of generators out there. However, using the above equation as a rough guide, you may estimate how much propane your normal generator will use.

How long will my propane tank keep the generator running for?

Most generators can run continuously for 24 hours on a single 100-pound propane tank. On a tiny generator, a 50-pound tank can run for twelve hours, but only for six on larger generators.

Standby home generators that run on propane often come with a 50-gallon fuel tank. Because of the increased storage capacity provided by larger propane tanks, electrical generators can keep running for several hours after their fuel supply has been depleted.

The generator's runtime is limited by the available fuel and the machine's size.

A 7 kilowatt propane generator should last about 65 hours on a full 100 gallon tank. In most homes, a generator of this size would only be used to power the most fundamental systems and appliances.

A backup generator with 15 kilowatts of power or more is recommended to meet daily needs. Always try to conserve as much energy as possible during times of crisis.

Just how long can emergency generator systems run for?

Unfortunately, we may need power for extended periods of time, although a portable generator is handy to have, if you need constant power for an extended period, a backup generator is your best bet.

The designers of these products envisioned their products being used for quite some time. Standby generators include robust engines designed to operate continuously for long stretches of time. They can also be connected to huge 500- or 1,000-gallon propane storage tanks or run on natural gas lines.

Remember that each backup generator has a maximum recommended load. Generally a generator can be left on for for two to three weeks without interruption and needing to give it a rest. 

You can operate your backup generator for longer than what's advised. Just be aware the generator and other electrical components in your home could be irreversibly damaged if you do this.

How big of a propane tank does a generator need?

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The size of the propane tank will be determined by the application. A tiny generator has a maximum operating time of four hours and requires a cylinder weighing no more than 20 pounds. Larger generators have a more forgiving 12- to 24-hour operating window.

A small generator can run for at least 4 hours and as long as 24 hours on a 20-pound cylinder of propane. This means that in the event of a protracted power outage, you could have enough fuel on hand to power your entire home.

Although a larger cylinder of gasoline takes up more space than a smaller gallon bottle, it may easily power your complete house.

Both 20- and 50-pound propane cylinders are available. The 20-pound cylinders can power most small generators for two to four hours, making them perfect for home use. You should probably get a cylinder that can hold 50 pounds for your generator. Propane retailers typically have the information on the size of fuel tank necessary.

What is the propane consumption rate of a generator?

The amount of time a generator can run on a single 50-pound tank of propane varies by make and model, but it's typically between 9 and 18 hours. While larger tanks can run for up to 24 hours, smaller tanks can only run for a few hours. 

Why use Propane to run a generator?

Propane is a great heating and cooking fuel that is easily accessible in most of the United States. Accessible in even the most remote areas, it is ubiquitous. Propane, in contrast to methanol and ethanol, has an infinite shelf life.

In addition to being cheaper to produce than gasoline, diesel, kerosene, or natural gas, it also has a very high energy density aka a greater power per unit of fuel volume.

In California, the price of propane is typically double that of gasoline at the same filling station. Unlike the market price, which remains relatively stable over time, the price per gallon at a station tends to rise and fall more frequently.

Propane, on the other hand, reduces emissions and produces fewer pollutants than either gasoline or diesel. Due to its superior cleanliness of combustion compared to other renewable fuels, it is an environmentally preferable energy source.

Propane is the most efficient heating fuel, with enough energy efficiency to keep a house warm for two or three weeks during the winter. Both small and big propane tanks can be purchased with considerable tax benefits.

How much does it cost to fill a propane tank?

Propane prices have been relatively stable over the previous decade. Over the past decade, the price of LP gas in California has ranged from $3.28 to $4.00 per pound.

The volatility of propane fuel prices can seem to vary a lot when you drive past the gas station on a daily basis, but based on this range, it appears that the price of propane is quite stable.

The price of propane will change based on factors such as the size of your generator and your geographical region. Prices per gallon can range from $3.85 to $7.00 at the wholesale level. Prices fluctuate with supply and demand, just like those of any other commodity.

How much does it cost per hour to run a propane generator?

Propane generators perform decently in terms of both power output and fuel costs. A 50-pound propane cylinder can create roughly 2 gallons of useful propane after four hours of operation or use as fuel for a propane generator.

Which fuel costs less to power a generator: gas or propane?

Similar to unleaded gasoline, the national average propane price is around $3 per gallon. However, the cost of propane can be as high as $4 to $7 per gallon at the wholesale level in some parts of California. However, when compared to the price of gasoline over time, propane fuel costs are not as volatile.

For how long can you keep a portable generator running on gasoline?

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Unfortunately, you cannot run a portable generator continuously if it is powered by gasoline; you must occasionally shut it off.

A gas generator's engine should be turned off before adding gasoline. In spite of the seeming ease of adding gas, doing so could potentially cause a catastrophic blaze.

When running, your generator's gasoline tank or the tank you're using to refuel can get very hot, and any spark from a spill or even fumes could easily start a fire that would spread. 

Running a gasoline generator continuously for any amount of time beyond its average runtime is dangerous and illegal in many places. Most gas generators have an operating time of 6-12 hours, but this can vary greatly depending on the model, size, and power requirements. 

Understand that some Generators are more fuel efficient than others, and more than you'd think, the Westinghouse WGen3600v can run for 18 hours on a single tank of fuel. This is one of the most economical generators around. 


To sum up, a portable gasoline generator can run nonstop for as long as the tank of fuel lasts, but not much farther. Typically, it takes between 12 and 18 hours.

Using a large propane tank, you will find that your primary limitation is often mechanical, typically engine oil. For most propane-powered systems, that's a time of five to eight days.

It is possible to survive for about 20-21 days if you have a large standby generator hooked up to a gas connection.

While most modern generators can use cylinders of any size, it's still a good idea to double-check your manual to be sure the canister you're buying is compatible with your particular model. They have also been manufactured with electric starters as of late, making them much easier to kick into action.

About Tom Bell

Hey, I’m Tom, the owner of Generator Reviews! I built this website to help you get the very most out of your generator and select the correct one for your personal circumstances. This site contains reviews of virtually every generator, detailed buying guides, as well as maintenance advice to help you keep yours in tip-top shape!


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