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how to size an air conditioner

Air conditioning is a must to keep your home cool in the summer. But do you know how to size an air conditioner for your home? If you don’t get it right, your will have problems. But don’t worry because we’re here to help.

This blog post will walk you through sizing an air conditioner for your home. We’ll provide information on BTUs and square footage and tips on choosing the right air conditioner for your needs. So read on to learn more!

Room Size Guide

You must first determine the size of your room to choose the ideal air conditioner size for your area. It is simple: double the length and breadth of your space. This aids in calculating the area of the space that you want to cool. If your space isn’t a perfect rectangle or square, you may simplify things by splitting it into portions and calculating the exact size.

You’ll need to figure out how many AC BTUs your space needs. To calculate the BTU necessary, multiply the total size of your room by 25. A general rule of thumb for sizing AC units is that each square foot of area filled requires 20 BTUs.

This value is conservative and accounts for various everyday weather variables such as humidity and rain. If your space is above the ground level, you’ll need to adjust for any heat that radiates from the sun. We recommend adding about 10% more BTUs for this eventuality.

For example, the formula for a room that is 20 feet long, 15 feet wide, and 8 feet tall would be:

20×15= 300 square feet

300×25= 7,500 BTUs

These estimates are meant to give you an approximate idea of how much cooling you’ll need. Many more aspects influence the actual cooling power required.

Room Height

You may size air conditioners based on the space of a room, but you may have not yet considered the height! The height of a room plays a role in determining how adequate a cooling capacity is.

The volume of air that has to be cooled in rooms with a high ceiling is substantially greater. Furthermore, wall-mounted mini-splits are more efficient than window-mounted air conditioners in cooling all of the air in a room.

A wall-mounted mini-split is significantly higher on the wall, and warm air rises, as we all know. As a result, a mini-split cools the heated air more efficiently than a window AC.


The location of your room also matters when choosing an air conditioner size. If your room is on the sunny side of the house, you’ll need a powerful AC unit to combat the heat.

On the other hand, if your room is on the shady side or in a basement, you won’t need as much cooling power. You should also take the climate of your area into account. If you live in a hotter climate, you’ll need a more powerful AC unit than in a cooler climate.

Wall Insulation

Wall insulation is a thermal inert substance incorporated into the room’s walls. In the summer, it keeps it cool, and it keeps it warm in the winter. Because wall insulation is an effective heat insulator, this is achievable. It implies it does not transfer heat well, resulting in cooling loss during the summer.

You will reduce your air conditioning needs if your walls are well insulated. The room will take a long time to cool down. If you don’t have insulation, the space will warm up once the AC is turned off. It must be left on for more extended periods and at a greater power level.


The windows of a room are critical for summer cooling. They let in sunlight, which heats. The room also transmits heat from the outside to the inside.

You’ll need to factor in the size of your windows when choosing an air conditioner for your room. If your room has a lot of windows, you’ll need a more powerful AC unit.

You can also use window treatments to help keep your room cool in the summer. Heavy drapes or blinds will block the sun’s heat, and reflective film can be applied to windows to reflect sunlight.

People Living In The House

The number of people living in the house also contributes to how much cooling you’ll need. If more people are in the place, more heat will be generated.

As a result, you’ll need a more powerful AC unit to cool the house down. If you have a large family or often have friends, you’ll need a more powerful AC unit than living alone or with just a few people.

Humidity Levels

Higher humidity implies more air conditioning is required. An air conditioner cools the air in the room while also acting as a dehumidifier. The temperature will quickly change when the extra moisture in the air is removed. You sense and improve the comfort of the surroundings.

If you reside in a region where the humidity level is high all year, it’s good to upgrade your air conditioner’s capacity.


Keep your house cool this summer by choosing the right air conditioner size for your needs! Consider the room height, location, wall insulation, windows, and the number of people living in the house when making your decision. And don’t forget about humidity levels—they can make a big difference in how much cooling power you need.

If you need some assistance in choosing the right air conditioner, call Furnace Repair Winnipeg for some help! Our team of experts will be more than happy to advise you on the best AC unit for your home. Give us a call today!

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