BTU calculation formula for air conditioner

What is air conditioner BTU? How many BTU i need per square meter? How do you calculate the size of an air conditioner? Our air conditioner btu chart will give you the answer shortly. We will also how you the air conditioning calculation formula table to help you calculate air conditioner btu for room size easily.

What is btu?

A British thermal unit (BTU) is a standard unit of power that is used in the United States and sometimes in the U.K. It shows the quantity of thermal power essential to increase the temperature of 1 pound of clean liquid water by one degree Fahrenheit temperature at which water has its utmost density (39 degrees Fahrenheit).

The Btu is a measure in the famous English system of units. Other countries use the Joule, the unit of power in the international system of Units. An aircon BTU is equivalent to about 1055 joules.

What is btu

The Btu is generally used as a quantitative specification of the power-transferring or power-producing capability of cooling and heating system such as ovens, furnaces, air conditioners, and refrigerators.

The warm output of computer equipment is generally specified so that it can be considered when planning the size of climate control systems in buildings. Computer gadget heat output is expressed in Btus per hour.

3.7 per hour is equal to one watt of heat dissipation.

Where does BTU come from

Although it was difficult to establish the true origin of the British Terminal Unit, the fact has it that it came from the mind of a British railroad engineer called Thomas Tredgold. During the course of his life, he changed his career path to becoming a specialist in heating and ventilating government buildings. The first mention of BTU was in an engineering publication in the late 1800s.

Why does BTU matter  

A good way to know how powerful or effective your air conditioner will be is by checking its BTU ratings. An air conditioner with a high BTU will be able to cool large spaces faster and more efficiently than a unit with a low BTU. Since technically, BTU is the amount of energy used by an air conditioner to remove heat, therefore, homeowners need to know the BTU of their unit so that they can be fully aware of its capacity.

Is higher BTU better for AC

No, having an air conditioner with high BTU does not automatically translate to efficiency and effectiveness, so they might not be considered to be better. Although if an air conditioner has a high BTU, such an air conditioner will be considered powerful. However, they can only be efficient if used in large spaces. If you install a high BTU air conditioner in small spaces, it will lead to a waste of energy, humidifying will become inadequate, and will cause your unit to cycle off too often. 

Is 10000 BTU enough

Unfortunately, I cannot answer your question directly with a yes or no because it all depends on the size of your space. For instance, if the size of your room in sq feet is 300, then 10000 BTU should be enough for you. However, if the size of your room is bigger than 300 sq feet, let’s say 600sq feet, then 10000 BTU wouldn’t be enough, you will need about 12000 BTU.

Is 2000 BTU a big difference

Yes, 2000 BTU will make a difference, but I wouldn’t go overboard by saying it will make a big difference. Although 2000 will make a difference, however, the difference it will make in terms of room size can be as small as 9.3 meters.

Does more BTU mean colder

Yes, more BTU means colder. The more BTU of your air conditioner, the more its capacity to supply cool air, and that is why it is usually recommended that homeowners use air conditioners with high BTU for large spaces.

Does more BTU mean more electricity

Yes, more BTU means more electricity. The higher the BTU of your air conditioner, the higher the electricity it consumes. To cool a large space, lots of energy will be used up in the process, and therefore, since energy comes from electricity, it means more electricity will be used up.

Is BTU the same as BTUH

No, BTU and BTUH are not the same. BTU measures the total number of heat that is removed in a particular house by an air condition, while the BTUH is used to determine the cooling and heating capacity of your unit per hour.

Is BTU per hour

Yes, BTU is per hour because they are usually calculated in hours.

Can BTU be negative

Yes, BTU can be negative if your unit loses lots of energy.

BTU in general household items

You will most generally find it to used to calculate BTU/hr (BTUs per hour) in cooling and heating machines but it is also used to measure the value of many other items.

BTU is used as a unit of classification in:

  1. Solar hot water heating
  2. Heaters
  3. Air conditioners
  4. Heating fuel
  5. Gas fire pits
  6. Cooking devices

Too much of a good thing

A top number of BTUs is not forever the answer. Using an aircon for living room level higher than required can cause the unit to chill fast, cycle off, and then, to maintain your wanted temperature, have to cycle on again soon after.

By cycling off and on in such fitful spurts of time, your aircon AC compressor will fast over-work itself. If done frequently and excessively, you will likely shorten the lifespan of your unit.

This is not exclusive to aircon units. The same goes for all air condition units, including the famous central air conditioners and windows as well.

Too little, too late

Using an aircon with not enough advised BTUs will keep you from reaching your wanted comfort level. The heat load will be very high for your unit to handle. This will cause your air condition unit to run continuously and never reach your set temperature level. Not to mention cut down its lifespan.

Does an 18000 BTU air conditioner need an isolator

Yes, an 18000 BTU air conditioner will require an isolator switch. The power supply of an 18000 BTU will be run directly from the DB board on a different circuit breaker by a qualified electrician right after or before installing your ac system. This should be done together with the installation of the outdoor isolator switch.

How to use btu to choose aircon size

What is aircon btu? How many btu air conditioner do i need? How big of a generator do i need to run a 5000 btu air conditioner?

Most people get worried when it comes to the selection of the best BTU air conditioner for room size. Others will go for those that are big thinking that the chilling effect will be excellent. The fact remains that oversized units are less successful and a waste of power. An extra-large unit is likely to chill the room fast but leave some wetness behind. The end outcome is a room that is damp and clammy.

Size is not a big deciding factor when you want to pick your aircon. All that affairs are getting the best unit that will be capable to provide the best chilling capacity in line with the room size. In essence, if you go for a unit that is too little, it may not be capable to provide the best cooling inefficiency.

On the other hand, an AC that is too huge will also not best for a room that is little. It will only cycle off and on and this will translate to power loss and misuse of power. Additionally, using a larger aircon in a little room will also affect the ability of the unit to dehumidify the room successfully.

As you strive to pick the right BTU for your room, it is best to consider other determining factors such as the type of climate and the height of the ceiling. Apart from the room type and insulation, it is equally vital to keep in mind the place and how much the room is naked to the sun.  This is the just way you will get the best power efficient chilling system that will make your house as relax as you want.

BTU rating number is extremely vital because it will support you to know how effective or fast an aircon stem can be capable to chill a room. These rating numbers generally range from 5,000 BTUs up to 20,000. As you proceed to pick the right AC for your home or commercial building, the easy calculation must be performed.

For starters, the size of the area where the unit is going to fixed is very vital. You can get the square footage of the room by multiplying the width and the length.  After this, it will be simple to get the best BTUs that you need using a British thermal unit calculator. Other things that will also come in contain nearest the sun and the full number of people that are likely to be using the room. For example, if the room in a sunny place, the BTUs are supposed to be increased by ten percent. The opposite should be performed if the room is placed in a shady location.

If the room is occupied by more than 2 people on a regular basis, six-hundred extra BTUs are supposed to be included for each extra person. Also, the condition should be the same if the aircon system is going to be located in the kitchen. In this case, the capability should be increased to 4,000 BTUs. The right place where you are going to install the unit is equally of huge significance.  For example, if you are going to install it at the corner of the room, it is best to look for a unit size that will be capable to distribute the air in the correct direction.

How many BTU for large rooms

Well, first of all, you have to determine whether you have a large, small or medium-sized room. If the size of your room in square feet is about 216, then you have a small room, if the size of your room is 320, you have a medium-sized room and if the size of your room is 616 and above, so then you have a large. Therefore, a room-size between 600-700 sq feet will need an air conditioner with 14000 BTU.

What size room does a 6000 BTU air conditioner cool

An air conditioner that has 6000 BTU can cool a room of 150 and 250 sq feet.

Will 2 5000 BTU vs 10000 BTU

If you are wondering which is better between using two small air conditioners (500BTU) or a big air conditioner (10000) to cool a large space, I would advise you to opt for 2 5000 BTU air conditioners because you will be able to balance out temperature. Plus you get to benefit from reduced energy consumption.

BTU formula for air conditioner

btu chart based on room size

Can you convert cfm to BTU

No, you cannot convert cfm to BTU. Cfm determines flow rate while BTU determines heat/energy consumption rate, which means they don’t have any connection whatsoever, and therefore, there’s no conversion between the two.


Most of the big aircon brands are extremely reputable in the HVAC market and are famous to be the most power-efficient systems. They have the highest power rating ( Mandatory Energy Labeling Scheme ) and also last for long before any breakdowns. Maintenance and use are equally pretty effortless. Nonetheless, all these advantages come at an expense of a costlier price. Above all, the system size you pick forever be in line with your needs.

Do you want to learn what is ahri certified in air conditioner?

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