How Much Propane Does A 20,000 BTU Heater Use (Explained)

How Much Propane Does A 20,000 BTU Heater Use

Have you ever wondered how much propane does a 20000 BTU heater use? Look no more. We´ve got you covered.

Whether you are a new homeowner coming across these units for the first time, looking for a new heater or cooling unit to replace an existing one, or simply want to be in better control of your energy consumption needs, understanding a little about this unit of measurement will help you make more informed purchases and uses of your propane.   

So, how much propane does a 20000 BTU heater use? A 20,000 BTU heater will use about a pound of propane in an estimated four and a half hours. However, this amount can vary depending on several factors regarding the household and the heater itself. 

What is a BTU?

If you have never heard the term BTU in measurement, you may be wondering what exactly it is. You may have even found that you have come across it in both heating and cooling units.

This is because it is a unit of measurement used in determining the energy required to increase or decrease something’s temperature.

The acronym BTU stands for British Thermal Unit. It is the amount of energy that is needed to raise one pound of water by one degree Fahrenheit.

 According to the United States Energy Information Administration (and also to give you a visual), one British Thermal Unit is about the same amount of energy released from burning a match.

Read also: How Much Propane Does A 40 Gallon Water Heater Use (Explained)

What Does the BTU Mean For A Heater?

Now that you know what a BTU is, you may be wondering what that means for your heater.  

To find out how much propane a heater uses, you will need to know how much BTU the heater uses per hour. If the heater is a 20,000 BTU heater (as in this example), then that means it uses twenty thousand BTU an hour.

This number should not be confused with the amount of heat the heater generates.

The other thing you will need to know is the fuel type and its BTU, in this case how much BTU a gallon of propane is.

What is the BTU of Propane?

Fuels of all types such as, propane, natural gas, electricity, wood and much more have been tested to see how much of it is needed to produce the energy required to increase the temperature of a pound of water.

Thankfully, the U.S. Energy Information Administration has a handy chart on their site with the BTU content of several types of fuels.

According to the United States E.I.A., when it comes to propane, one gallon of it is equal to 91,452 British Thermal Units.

Now that you know how many BTUs are in one gallon of propane, you can find out how much propane a twenty thousand BTU heater will use in a set amount of time.

How To Find Out How Much Propane A Heater Uses

Now that we have how much energy the heater uses (20,000 BTU) and the BTU of propane (91,452 BTU), we can easily find out how long one gallon of propane will run your heater.

To do so, divide the BTU of propane by the energy consumption of the heater as follows:

91,452 ÷ 20,000 = 4.526

This means that your twenty thousand BTU heater will use one gallon of propane over a period of approximately four and a half hours.

To put this into an even better perspective, one of the most common propane tank sizes found in homes across America are five-hundred-gallon tanks.

“If your propane tank happens to be this size and the propane were to be solely used for heating, then that would mean it would run the heater for up to 2,286.3 hours.”

Or approximately 286 days with the heat being left on at a reasonable temperature for eight hours out of the day.

There are, however, various factors that may cause your heater to use more or even less than the amount above.

 Read also: How Much Propane Does a Blue Flame Heater Use (30000 BTU)

Factors that May Cause A Heater to Use More or Less Energy

Not every household is the same, nor is every heater. As a result, the amount of propane a twenty thousand BTU heater uses may increase or decrease from one house to the next.

Some of these reasons include the following:

Using the Wrong Size Heater

If you don’t know the right size heater to get for a room or house, then a wrong purchase can have you using more propane and spending more money on heating your household than you should.

An easy formula to find out what size heater you should get is to take however many square feet the room is and multiply it by twenty British Thermal Units.

This would mean that a twenty thousand BTU heater would be effective at heating a room the size of 1,000 square feet.

Anything bigger will require your heater to use more energy as it attempts to raise the temperature of a room larger than the unit was meant for.

 The heater will struggle to both reach and maintain the ideal temperature throughout the room.

Temperature Settings Used

As mentioned, every household is different when it comes to the amount of energy used to heat it. Some people prefer to set their heaters higher than others, which in turn requires more energy to achieve, and thus more propane will be used.

To get the most efficient use out of your heater and your propane, you won’t want to set the temperature too high. When a house reaches a certain temperature, the heat inside will begin to transfer outside the house and be lost.

As the heat is lost, the heater will kick back on and use more propane to keep it at a higher temperature.

As a result, most energy suppliers will recommend setting the heat anywhere from sixty-eight to seventy-two degrees Fahrenheit.

With the heater set within this range, you won’t have to worry as much about the transfer of heat from inside to outside.

It is also a reasonably comfortable heat setting that won’t have anyone feeling too hot or too cold.

Age of Heater and House

The age of your heater, as well as your house, can play a role in how much propane your heater uses.


Heaters last a long time, but as with anything, age will eventually be its demise. An old heater can begin to lose its efficiency over time.

Even with the best of maintenance, your heater will begin to require more propane to generate the energy needed to heat up an area.

Newer models are designed to be more efficient, so if you feel your heater is failing on you and using a significant amount more of propane to do its job then it is likely a good time to invest in a newer, more efficient model.


As mentioned earlier, once it becomes too hot, heat will begin to transfer out of its enclosed area and become lost in the process.

To prevent this from happening, houses are built with insulation. However, some households retain heat inside better than others, with newer houses having better insulation.

Even if the temperature is within the recommended range (sixty-eight to seventy-two degrees Fahrenheit) an older house is more likely to use up more propane per hour than a newer one.

Keeping it warm will be more of a challenge as the heat is much more easily able to escape.

Season and Climate

It is no secret that a household will require more energy to heat it up in the winter months. Seasonal hikes in how much propane one uses to warm their homes are common during the winter and should be no surprise.

However, the overall climate of the housing will also play a role in how much propane is used by the heater. Someone living in Pennsylvania will likely be using more propane to warm their homes than someone living in Florida.

A hotter climate household will certainly fall short in propane use compared to that of a household in a colder climate.

As a result, the estimate that is given above of using one gallon every four and a half hours should be taken with a grain of salt and viewed as only a rough estimate.

Final Thoughts…

These are but few factors that affect how much propane your twenty thousand BTU heater will use in a given amount of time.

The differences between how much propane is used in one household and the next can be vast as a result.

Despite all these factors though, the equation above can give you a general estimate as to how much propane a heater uses.

Which for a twenty thousand BTU heater is a gallon of propane in four and a half hours.


Mike Gilmour

Hi, I'm Mike, co-founder, and editor of RV and Playa. My passion is traveling (with my RV) and enjoying the day at the beach (Playa)! Well, I originally created this blog as a way to share what I've learned by experimenting with the RV lifestyle, and I want to help others develop in life through new skills and opportunities.

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