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What Size Window Air Conditioner Do I Need?

What Size Window Air Conditioner Do I Need?

Feeling fresh, looking good, and saving money, sounds impossible unless you determine the size of the window air conditioner for your home wisely. This device is crucial to provide a cooling effect during hot days, but it is also of great importance to regulate the humidity in your room.

A too-big window air conditioner can leave the effect of a wet environment, as it will cool the air too quickly, and it won’t eliminate the necessary humid. On the other hand, if being too small for the room, the air conditioner will continuously work with low efficiency, and it will result in higher electrical bills. Your goal is to pick out the ideal window air conditioner size for your home. Let’s take a close look at the issue.

Cooling Capacity Factor and Size

Different factors influence the window air conditioner size you need. Therefore, you should take all of them into consideration before even deciding which one to buy.

Keep in mind that you can’t use the same window air conditioner size for large and small space. Therefore, one of the first measurements you will need is the size of the room you want to cool.

The essential term for determining the right size for the window air conditioner is BTU (the British Thermal Unit), which allows you to measure heat power. In other words, it represents how much thermal energy you need to heat the temperature of 1 pound (0.45 l) of water for 1 Fahrenheit degree.

In case of window air conditioner size, you should calculate how many BTU’s your new air conditioner should have, to remove the heat efficiently. The calculation of the BTUs requires several stages.

The first phase – Square footage of the area

In the very beginning, you will need the measuring tape to determine the width and length of the room. Then, you should multiply the length and width footage to get the square footage.

The second phase – The floor position

There is a big difference when you plan to cool the room on the ground floor or in the attic. In fact, you will always need to cool the attic more since solar heating there is stronger and more intensive than on the ground floor.

Therefore, once you calculate the square footage of the room, you should multiply that number with the constant.

  • If the room is on the ground floor, multiply it with 30
  • If you need the window air conditioner for the kitchen or second floor, multiply it with 40
  • For over 8 feet (2.4 m) high ceiling, you need to add 1000 BTUs for every foot

The third phase – The number of people in the room

In case you need a window air conditioner in your office or a living room, where a lot of people spend time during the day, you should consider their number, as well. The standard is two people per room, and you need to add 600 BTUs for each additional person.

The fourth phase – The position of the area regarding the sun

Of course, it is not the same if the room is in the shade, or it is on the sunny side of the house most of the day. That means you need to add an extra 10% to the number you have calculated above if it is on the sunny side.

Window air conditioner sizing – What Next?

After calculating the BTUs for your window air conditioner size precisely, you need to round the number obtained.

For example, if you get 7,120 BTUs, you should round it down to the closest thousand. In this case, it will be 7,000 BTUs. Likewise, if you get 7,970 BTUs, you need to round it to the nearest thousand. In this particular case, it will be 8,000 BTUs.

In any case, no matter if the number is lower or higher, always round it to the closest thousand.

If you wish, you can calculate even more specific BTUs taking into consideration the type of your room, the type of insulation installed, and the climate in the region where you live.

For those specific calculations, you need to use one of the precise BTU calculators. Nowadays, you can find professional BTU calculators on the Internet. Everything you need is to measure the room correctly.

Actual Size of Window Air Conditioner You Need

Actual Size of Window Air Conditioner You Need

So far, you have got information about the capacity of the AC, which suits your room the best. However, you need to think about the physical window air conditioner size, as well. It is necessary to pick out the device fitting your window adequately.

Most of the window air conditioners on the market are the standard ones. They are usually made for both single-hung windows and double-hung windows. Nonetheless, you need to use the measuring tape and precisely determine the size of your window.

Always pay attention to the width and height of the inner parts of the window frame. The best way to finish the job quickly is to open the window widely and take the necessary measurements.

Keep in mind that every AC has dimension specification for the proper window width and height. Before choosing the perfect window air conditioner size for your room, you should check the maximum and minimum width measurements on the manual. Then, pick out the right model according to your window width.

In case you can’t fit your new AC precisely, always choose the model which is not too bigger for the dimensions of the window frame.

The window air conditioner always comes with a window insulation kit, which will help you fill in and seal the parts that don’t lay accurately. If you take care to choose the closest possible size to your measurements, you won’t have too much trouble to finish the job. The better the fit, the fewer holes you need to fill in with insulation materials.

Energy Efficiency Ratio

When choosing adequate appliances for your home, you should always think about energy efficiency. The same is with the right window air conditioner size. Your goal is to find the device that saves energy as much as possible.

Therefore, you should check the right model based on EER (the energy efficiency ratio). It is actually the standard notification for energy-saving appliances and represents the BTUs per hour over its wattage.

The rule is that the higher EER number means better efficiency regarding the energy. Therefore, you should always check it before buying the device. When you want more efficiency, you will need to choose the air conditioner with a higher number.

Usually, you can see a star next to the number, as well. That means this particular model is in a group of ‘energy star models,’ which will additionally save you electricity and money. Plus, they are entirely eco-friendly.

Other Window Air Conditioner Features

Other Window Air Conditioner Features

Except for the obvious ones, there are some features you should also look into. They will help you get the best possible service for the excellent value of money.

Easily removable filter

In case you can choose, it is always better to have an air conditioner that is easy to maintain. Filters are crucial parts since you need to clean and remove them very often. Therefore, you should try to pick out the model with an easily accessible filter.

AC remote controls

Most of us don’t pay attention to this piece of equipment, but you really need to check it. Since you will use it all the time to operate your window air conditioner, you need the model with simple, understandable, and visible indicators. Otherwise, you can find yourself in uncomfortable situations after pressing the wrong button.

The display on the AC

Nowadays, the best option is the air conditioner with a digital display. It should be big enough for you to see the selected function, temperature, and mode of the AC program effortlessly.

Also, always choose the remote control with a display, if possible. In case one of the screens doesn’t work, you will always have the other one to check for the necessary information.


A built-in timer is a helpful piece, which will help you regulate the temperature in your home comfortably. With it, you can quickly turn the device off and on without even being at home.

Smart AC

These models are an excellent choice for you if you like to control the AC from a distance. Since they are more expensive than regular ones, you should think if you need it before purchasing one.

A window air conditioner with dual function

These window air conditioners can perform both heating and cooling functioning. They are an excellent choice for the regions without drastic variations in temperatures. Also, you can use this model in spring or fall when you don’t need too much heating.


The air conditioners have become the necessity of modern society. If you choose the right model of appropriate size, you will save a lot of time, energy, and money. Plus, you will make your home a pleasant place for living, even during the hottest days of the year.

Yes No Wheel

Wednesday 19th of October 2022

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