BTU Air Conditioner | What is BTU [ The Ultimate Updated Guide 2019 ]

You must know these things before investing in BTU Air Conditioner

After spending years in the HVAC industry, I have always been asked questions regarding BTU Air Conditioner requirements, repeatedly.

One of the most common questions that my readers ask me is “What is BTU”.

Another question that people ask is “how many BTU air conditioner do I need?

Even if you understand that it’s a kind of measurement unit, maybe you are not sure how this unit is used every once in a while for describing the heating capacity of the AC units.

In case you were wondering why the BTU capacity of an AC unit matters to you, let me be your friend and guide.

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Continue reading below:

So, What Exactly BTU Stands for?

I would quickly guide you through the definition and functionality of BTU.

The full-form of BTU is British Thermal Unit, which is widely used across different appliances as a means of measuring thermal efficiency of the respective machinery.

The wide acceptance of this particular measurement unit makes BTU an international standard.

Historically, this particular thermal energy measurement unit was first used a long time ago; during the 1880s. Since then, the unit is popularized across numerous appliances.

So what does BTU Air Conditioner, mean for you?

What is btu
What is btu

Let’s check out:

This is how BTU is measured

Let me assume that you have one pound of water at room temperature.

Now, you might want to raise or reduce its temperature by one degree Fahrenheit.

This is when BTU comes in handy.

In simpler terms,

it is the BTU that refers to the amount of heat you would require to generate; for raising or reducing the water (1 pound) temperature by 1 degree (Fahrenheit).

Although BTU is a common standard of heat measurement among numerous appliances, the use of the same might differ to some extent depending on the type of machine you are using.

What is the BTU calculation formula for the Air Conditioner?

Let me give you an example of how this works.

For instance,

in the case of a heat pump or a furnace, BTU is referred to as the heat output of the particular unit.

On the other hand,

in cases of your air conditioning system, BTU is the capacity of the particular unit for successfully removing warm air out of your room. Think about it!

In case you might be asking yourself about the BTU calculation formula for air conditioner, let us tell you something.

The BTU is the cooling or heating capacity of any HVAC system.

Let me explain it in the next paragraph.

If the label on your AC reads 10,000 BTU, it denotes the air conditioning system’s capability of removing 10,000 BTU of heat from your room in an hour’s time.

And guess what, the average heat released by a person sitting idle in a room measures up to 230 BTU per hour.

BTU vs eer
BTU vs eer

Should You Opt for a Lower or Higher BTU Air Conditioner?

You would probably assume that a higher BTU AC unit might be more effective than the ones with a lower BTU.

But wait, let me tell you something.

It’s not at all necessary for a higher BTU AC unit to work better than the lower BTU AC systems. Multiple reasons play an important role in such an unpredictable nature of the AC.

First of all,

the size of your rooms dictates the amount of heat to be removed from the particular space.

Among other valid reasons are the window types that you have installed in your home, the roof height evident in your living space, along with the type of duct-work evident in your room.

Here is the standard BTU list for your room.

BTU Chart Based on Room Size

Room Size in sq. mRoom Size inssq. ft.BTU’s Needed
14 sq. m.150 sq. ft.5,000 BTU’s
23 sq. m.250 sq. ft.6,000 BTU’s
28 sq. m.300 sq. ft.7,000 BTU’s
32 sq. m.350 sq. ft.8,000 BTU’s
37 sq. m.400 sq. ft.9,000 BTU’s
42 sq. m.450 sq. ft.10,000 BTU’s
51 sq. m.550 sq. ft.12,000 BTU’s
65 sq. m.700 sq. ft.14,000 BTU’s
93 sq. m.1,000 sq. ft.18,000 BTU’s
111 sq. m.1,200 sq. ft.21,000 BTU’s
130 sq. m.1,400 sq. ft.23,000 BTU’s
148 sq. m.1,600 sq. ft.25,000 BTU’s
176 sq. m.1,900 sq. ft.28,000 BTU’s
251 sq. m.2,700 sq. ft.36,000 BTU’s


How much BTU you should choose?

In my own experience, the larger your room is, the more BTU enabled AC is what you need.

On average,

you would require a 60,000 to 80,000 BTU Air Conditioner to effectively cool your entire home.

Again, it turns out that the BTU requirement is subjected to change depending on multiple reasons, and that’s why I fully recommend you to consult with a highly experienced HVAC professional to make sure you are installing the AC with the right BTU capacity.

You wouldn’t want your money to go to waste, would you?

Here is BTU Chart Based on Room Size. You can save it for future use.

BTU Chart Based on Room Size Air Conditioner
BTU Chart Based on Room Size Air Conditioner

What else should you know about BTU?

You are probably asking yourself all the questions regarding BTU and how it is measured.

In that case,

let me explain some of the most important facts regarding this international measurement unit.

BTU belongs among those non-metric units of energy that is used across the USA (United States of America), apart from being used in the UK (United Kingdom).

On the other hand, most of the other countries use joule (J) as an SI (international system of units).

In terms of measurement,

1 BTU equals to approximately 1055 joules; which is equivalent to 1055 watt-seconds.

As far as the computers are concerned, the BTU is used as a means of measuring the amount of output across the heat generating machines.

In that regard, the heat output is showcased as BTU/h (BTU’s per hour).

It’s worth noting that 1 watt of heat dissipation equals 3.7 BTU/h.

The Use of BTU in Air Conditioners

As I have mentioned earlier, in AC machines, the BTU is referred to the machine’s capability of removing a specific amount of heat from a given room; in an hour.

Now, at this point, you might be asking yourself what are the approximate BTU ranges available across different AC models. Let us go through it:

  • In the case of portable air conditioners, the BTU ranges between 8,000 and 12,000.
  • For split system ACs, the BTU ranges somewhere between 9,000 and 36,000.
  • On the other hand, for AC units that are mounted on the windows, the BTU is subjected to range between 3,000 and 25,000.

When we are talking about the central AC units, it must be kept in mind that there is only a single compressor equipped for the entire house.

These AC systems use tonnage for measuring their cooling capacity and BTU isn’t the standard used.

We’re not through yet, as the tonnage can be easily converted into BTU for a simple reading process.

To do that, all you need to do is remember that 1 AC ton equals 12,000 BTU/hr.

If such a calculation procedure is mastered, it would be way easier to conclude that an AC with 2-ton capacity can remove 24,000 BTU heat from a room every hour.

And guess what, the tonnage in a given AC has hardly anything to do with the unit’s weight.

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How to save money on AC maintenance Tips
How to save money on AC maintenance Tips

Does a Bigger AC Generate Better Results?

When you are out there in the market, looking for the perfect AC, it’s easy to assume that the bigger the size of the AC shall mean better performance.

Well, let me tell you something in this regard.

Size doesn’t matter!

There are many cons associated with larger ACs.

First of all,

they are expensive and can drastically add up to your electricity expenses, quickly.

The installation costs for these machines are also too high, as compared to smaller ones.

When you are using a large AC to cool a small space, it is obvious that you would require turning the AC off after regular intervals.

After frequent turn-on and turn-off of the machine, the AC unit would be exposed to additional wear and tear, which in turn shall increase your expenses.


And that’s not the end of the story yet:

In a humid area, ACs with higher compressor strength would add more humidity to your room.

This mainly happens because the compressor stays off for a longer period in these larger ACs, which restrict the device from removing maximum moisture from the air.

Now you might think that a smaller BTU Air Conditioner is more effective than an AC unit with higher BTU.

Well, let me assure you that this isn’t the case at all.

When an AC’s size is too small, it might be required to run continuously and at the same time, it might not be able to cool down your room as much as you would expect.

Therefore, it is necessary for you to be specific while choosing the right AC with the perfect BTU capacity.

By cycling the AC on and off in a shorter period, you are more likely to damage its compressor; given the fact that the compressor has been overworking as compared to its original requirement.

Excessive repetition of the process would lead to shortening of your AC unit’s lifespan.

In case you are thinking that such a negative phenomenon is popular exclusively among the portable AC units, let me explain that such a massacre is likely to happen even in the central and window air conditioners too.

Convert BTU Table

BTUOther Unit
1 BTU0.293 watts
1 watt3.412 BTU
1 kilowatt3412.142 BTU/hr
1 kilowatt1,000 watts.
1 btu1.05506 Kilojoule
1 Kilojoule0.947817 BTU
1 btu1055.06 Joule
1 Joule0.000947817 BTU
1 btu0.252164 Kilocalorie
1 Kilocalorie3.96567 BTU
1 btu252.163 Gram Calorie
1 Gram Calorie0.00396567 BTU
1 btu0.00029 Kilowatt hour

Choosing the Perfect AC

I guess you are now overwhelmed by the problems associated with inappropriate BTU AC units.

I won’t make the process more of a dreadful experience for you.

You can overcome such a situation by choosing the right BTU AC unit for your needs.

It’s necessary to consider the total square footage of your room and consult the same with your desired HVAC Company.

With the years of experience these HVAC experts have, you can blindly trust them and get home that perfect BTU Air Conditioner you had been looking for in the first place.

I wish you a happy AC shopping experience.

What’s your main takeaway from BTU Guide (What is  BTU?

Or maybe you have a question about something you read.

Either way, go ahead and leave a comment below with your thoughts.

Cheers 🙂

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BTU Air Conditioner | What is BTU
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BTU Air Conditioner | What is BTU
In simpler terms, it is the BTU that refers to the amount of heat you would require to generate; for raising or reducing the water (1 pound) temperature by 1 degree (Fahrenheit).
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BTU AIR Conditioner
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