BTU air conditioner

How many BTU air conditioner do I need?

Wait! Let’s get a few things straight before we jump into how many BTU air conditioner you need.

Size is everything

When you’re trying to decide what size of air conditioner is right for your home you have to remember that there is no such thing as one-size-fits-all. An undersized air conditioner will run continuously because it won’t be able to adequately satisfy the temperature demands of the home. This puts added strain on the air conditioner and causes it to draw higher than normal amounts of electricity. On the other hand, oversizing your air conditioner will result in short cycling. Short cycling occurs when the air conditioner comes on, and satisfies the thermostat too quickly leaving areas of the home uncooled and reducing the amount of dehumidification that it can achieve in the dramatically shorter cooling cycle. The constant stopping and starting of the unit also increases the amount of unnecessary wear and tear. So, you can see that it’s very important to choose the air conditioner that adequately meets the needs of your home. But how do you know which one you need?

Here is what BTU means

The first thing to understand is that an air conditioner’s ability to cool is rated in tons. A ton refers the ability of the air conditioner to remove 12,000 BTUs of heat energy in an hour. As such, a two ton unit will cool 24,000 BTUs, three ton 36,000, etc.

What size air conditioner do I need? Do a Manual J calculation first

In order to get the most accurate idea of your home’s cooling requirements and determine the right BTU air conditioner, you will need to complete a Manual J Load calculation. This can be difficult to do on your own, as they are complicated and require a lot of details to do accurately, but there are software programs to help with this and they will give you the most accurate results. Luckily, we take you through this process here. Manual J Load takes many factors into account such as the insulation value of the home, windows, doors, and even the number of occupants to provide the most comprehensive view of your heating and cooling needs.

Or try this quick method to find the right BTU air conditioner

While the most accurate, Manual J Load is not the easiest thing to calculate. There is a simpler way to find a reasonable estimate that, while not as accurate, is often used to quickly determine the appropriate sized air conditioner for the average home. To do this, calculate the square footage of the spaces that will be cooled and add them together. Then determine what style of home you have (bungalow, semi-detached or detached) and when your home was built. Since building codes have changed over the years it can drastically affect what tonnage you might require. Once you have these two pieces of information you can relate them to this chart below to have a reasonable idea of what you might need:

House TypeSquare FeetTonsBTU
Bungalow (built after 1980)Up to 1,2001.5 ton18,000
1,200 to 1,5002 ton24,000
1,500 to 1,8002 ton
1,800 to 2,5002.5 ton24,000
2,500 to 3,5003 to 3.5 ton36-42,000
Bungalow (built before 1980)Up to 1,200Up to 2 tonUp to 24,000
1,200 to 1,5002 ton24,000
1,500 to 1,800Up to 2.5 tonUp to 30,000
1,800 to 2,5002.5 to 3 ton30-36,000
2,500 to 3,5003.5 to 4 ton42-48,000
Semi-detached 2 storey home (built after 1980)Up to 1,500Up to 2 ton
1,500 to 1,8002 ton
1,800 to 2,200Up to 2.5 ton
2,200 to 3,0002.5 to 3 ton
Detached 2 storey home (built after 1980)Up to 1,3001.5 ton
1,300 to 1,7001.5 ton
1,700 to 2,5002 to 2.5 ton
2,500 to 3,5002.5 to 3 ton
3,500 to 4,5003.5 to 4 ton
Detached 2 storey home (built before 1980)Up to 1,300Up to 2 ton
1,300 to 1,7002 ton
1,700 to 2,5002.5 ton
2,500 to 3,5003 to 3.5 ton
3,500 to 4,5004 to 5 ton