What is BTU?

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Last Updated: 03/25/2021

Are you shopping for an air conditioner and keep coming across the term BTU? Well, if you are wondering what this means, we have everything you will need to know in this article. That way, you can get back to searching for the perfect air conditioning unit for your home and room size.

The following is what you should know about BTU and air conditioners. While shopping, a dealer can let you know more.

Let us begin!

What Does BTU Mean?

What is BTU?

To start, you will need to know the answer to "what does BTU mean?". It stands for British Thermal Unit.

This acronym shows up all the time when you are searching through air conditioners, since it is a unit of measurement important to them. The unit represents thermal energy, specifically the amount of energy that you need to adjust the Fahrenheit one pound of water up one degree at sea level.

When BTU shows up in relation to air conditioners, the measurement is used to show how much BTUs the unit can alter the air. In other words, how well it can cool down your home.

However, a higher BTU might not be what you need in your home air conditioning unit. But, how do you call exactly what you need? Well, we will cover this information and more below. We made sure to research what the air conditioner experts had to say.

Can There be Too Much BTU in an Air Conditioner?

Yes, a higher range of BTU might not be what you need in an air conditioner perfect for your home. This is because you will need to look at your room size and more before you can determine what BTU level is right for your home. When you use a system with a BTU amount that is higher than what you need, the unit will quickly cycle on and off, so that it can maintain your selected temperature.

However, cycling on and off quickly uses a high amount of energy- which is not efficient at all. Plus, air conditioners are not designed to do this. You will wear out the components inside of your machine much faster this way. In short, you will greatly reduce the expected life span of an expensive air conditioning system when the BTU level is too high.

Keep in mind that this is the same for all types of cooling units, no matter the size. Since BTU refers to the amount of change in heating in a space, you will need to take time to select the correct size of cooling unit. You can also have a BTU rating that is too low, which will have different effects. Overall, you want to find a suitable number in the middle. A dealer might be able to assist you further if you are stuck.

What Happens When the British Thermal Unit is Too Low?

When you are running an air conditioner that does not have enough BTU, the machine will struggle to reach the temperature that you set. This can cause the unit to warm up quite a bit.

If the air conditioning system can not cool the room, it is going to be running constantly. When that happens, the longevity of the system is going to drastically drop.

So, you can have issues if the air conditioner has a BTU rating that is too high or too low. How can you tell what BTU level will work for you? Well, you are going to need to check out the area of the room that you want to provide with air conditioning first.

The Recommended BTUs Per Square Footage


If you want to figure out the exact levels of BTUs that you need, the best call would be to use an online BTU calculator. There are options for both heating and cooling units online, since BTU ratings are also used to measure how much a system can raise the temperature as well.

Although, you can also follow a general rule when it comes to square footage and needed BTU levels. To find the rating of BTU per square foot needed, you can follow these formulas. For BTU required to raise the temp, multiply the square footage by 20 BTUs per square foot.

As an example, if your room has 1,000 square feet, you will need 20 000 BTU to warm it. This is because 1,000 square feet X 20 BTU is 20,000 BTU per square foot.

For air conditioning units, you can use the same formula. An air conditioner needs 20 BTU for each square foot of space in an area. You will also want to think about the height of your ceiling and the sizes of windows. If your area is not insulated well, cool air can escape easily, meaning you will need more cooling power.

And finally, it is easy to find the square foot area of a room. All you need to do is measure the length and width, then multiply the numbers together.

What Does It Mean 12000 BTU?

Since one BTU is the amount of energy (or amount of heat) needed to raise the temperature of one pound of water one degree F, 12 000 BTU is equal to 1 ton.

A 12 000 BTU air conditioner would be best suited for rooms between 450 and 550 square feet. Most window air conditioners have 10 000 BTU, so you will want to check the area of your space before purchasing. In most cases, 12 000 BTU units might be too much for your area.

Choosing an Air Conditioner Size

Choosing an Air Conditioner Size

Now that you know all about BTU levels in heating and cooling units, you can choose the perfect type of air conditioner. This is because the unit BTU also refers to the size of the air conditioner. Let us use another example.

How Many BTU Do I Need For a 12x12 Room?

A 12x12 room is 144 square feet. So, you multiply that number by 12 BTU and get 2,880 BTUs needed to cool the room. This is not a lot of space to cool or heat, so you should be able to find a decently priced air conditioner at a suitable level for this room.

You can also consider the BTU per hour. This output will let you know how long it takes for the system to make that one degree fahrenheit adjustment. If more energy is needed for more heat output, you will want to ensure that the machine is also efficient, so your energy bill is not deeply affected if you need a lot of heating.

Is Higher or Lower BTU Better?

That is going to depend on the space of your room. Plus, if you live in a warmer area, you will need more cooling power- which means more BTU.

It will also depend on how well insulated and how much of your home you are trying to heat or cool. If you are trying to provide cooling for the whole house, you would be better off with an HVAC system, instead of an air conditioner with tons of BTU power.

Or, if you are trying to heat your whole home over a single room, you will want to consider a number of gas or heating oil systems.

Overall, your new unit will require as many BTUs as the area of your space requires. Going to far above or below that size can cause plenty of issues within your new machine down the road.

Do Heat Pumps Save Money?

Heat pumps are used to transfer thermal energy from a heating source to a thermal reservoir. This applies more heat from the air to a space. They essentially take heat out of a cold area and let it into a warmer zone. In these cases, BTUs per hour still refers to the amount of change in heating water.

In a United States study, it was determined that heat pumps can save you money- about $1,700 in a year. This is because natural gas prices are rising and the cost of electricity is lowering.

While that number is pretty higher, it also depends on how efficient your systems are. To reach a good savings, you may want to contact a professional dealer who handles these types of units. They can let you know if you need 1,000 BTU or more.

Final Thoughts

Once you know how to do it, calculating exactly how many BTUs you need for cooling and heating is simple to figure out. You will be able to determine if you need to update to a unit with more BTU or even if you have to downgrade for better efficiency.

BTU is the measurement of the level of heat needed to raise or lower the temperature of one pound of water by 1 degree Fahrenheit

. So, what BTU rating do you need for an 1 000 square foot area? About 20 000 to 21 000 BTUs should suffice. You will also need to consider you insulation and the form of any windows or doors when determining this exact number. You should be able to go a little higher or lower without any harm to your machine.

So, know you know the answer to "what does BTU mean?"- British Thermal Unit. This number is a good call for the level of energy a machine will use to adjust the heating and cooling your house.

If you have any questions, feel free to reach out to us. We enjoy engaging with our readers and would love to hear your thoughts on selecting a unit for use at home.

We update and post content frequently on this subject, so be sure to follow us if you would like to learn more about United States heating and cooling products.

Charles Jasper

Charles Jasper is the owner and main author of Home Climate Center. He has a degree in Engineering and 20 years experience on working on HVAC systems. He has a passion for everything related to home improvement and loves to travel. When he is not working, you might find Jasper working on projects around the house or organizing a camping trip.

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