What Size Air Conditioner Do I Need?

Let’s be honest, size matters. Especially when choosing the correct BTU size for an air conditioner you need installed in your new home or office. Choose too small a unit, you could end up with a room that’s not cool enough, or with an air conditioning unit that overheats soon enough. On the other hand, too large a unit for the space will not remove the necessary moisture from the room, making it feel clammy and uncomfortable. Here’s how to calculate BTU to find the perfect AC unit for your needs.


What is a BTU?

A BTU or British Thermal Unit is a measurement of how much energy is required to raise the temperature of one pound of water by one degree. That might not sound useful when it comes to aircons in your home or business but the underlying calculation is very important to staying comfortable.

Each ac unit or heater is rated to produce a certain number of BTUs.There are many factors that go into calculating BTUs, so we have put together a set of tools to help with air conditioner sizing.


Air Conditioner BTU Calculator Chart

The chart below is a great starting point for sizing your AC. These BTU calculator is based on a standard room with 8-foot ceilings, two windows and one door. If the room has more windows, doors or higher ceilings, adjust the BTUs upward.

Other factors in determining the BTU calculator result, would be the room’s purpose. Kitchens normally have more heat thanks to stoves and ovens, and rooms with computers and other electronics give off extra heat. Therefore, these rooms would require bumping the air conditioner size up.


What else should I look for when buying a room air conditioner?

Remember that bigger is not always better! Buying an air conditioner that is too large does not provide better cooling. An oversized air conditioner is actually less effective — and wastes energy at the same time. Make sure your unit is properly sized by using the BTU Calculator provided.


Properly Sized Room Air Conditioners

Room air conditioner sizing is all about matching the room size to the air conditioner size. A unit that is too big will be less effective and offer reduced air conditioner efficiency. Air conditioners remove both heat and humidity from the air. If the unit is too large, it will cool the room, before it has a chance to remove the humidity.

The result will be a room that’s not very comfortable to spend time in That cool moist air will make the room feel damp and clammy. The most energy efficient air conditioner is sized to the square footage of the space to be cooled. Getting the right size means getting the comfort and the energy efficiency right.


Size Of The Area (m²):

To determine the BTU size of the unit, the size of the area to be treated must be calculated:

Length of Room x Width = m²
If the height of the ceiling is over 3m, then add on the increased percentage of the area.
Calculate the size of your room by multiplying the length of your room by the width.

Room size of maximum : Air conditioner size required :
18 m² 9 000 BTU
25 m² 12 000 BTU
36 m² 18 000 BTU
50 m² 24 000 BTU
60 m² 30 000 BTU


Air Conditioner Size On Standard Power Supply:

These air conditioning units don’t need a separate power supply and can be plugged into a wall socket:

• Room size up to 18m² = 9 000 BTU
• Room size up to 25m² = 12 000 BTU
• Room size up to 36m² = 18 000 BTU


These Aircon Units Need A Separate Power Supply & Isolator Installed To Which Outdoor Unit Must Be Connected Directly:

• Room size up to 50m² = 24 000 BTU
• Room size up to 60m² = 30 000 BTU
• Room size up to 72m² = 36 000 BTU
• Room size up to 96 m² = 48 000 BTU
• Room size up to 120m² = 60 000 BTU