Skip to Content

What Size Air Conditioner Do I Need? 5 Things to Consider

outdoor air conditioning unit on concrete slab

When you start shopping for a new air conditioner, one of the most important things to consider is the unit’s size. An air conditioner’s size is another term for its capacity. It’s crucial to buy an air conditioner with the right size (or capacity) for your home. A unit that’s “too big” or “too small” will lead to efficiency problems.


An air conditioner’s capacity is measured in tonnage. You can buy a residential AC unit that’s as low as 1.5 tons or as high as 5 tons. How many tons your air conditioner should have can be affected by numerous factors.

Here are some factors that can have the most impact:

1. Your Home’s Indoor Square Footage and Number of Stories

If you own a 2,000 square-foot, multi-story home, a small, 1.5-ton AC unit will struggle to perform. Conversely, if you own a 1,000 square-foot condo, a huge, 5-ton AC unit will run for extremely short cycles and fail to cool your home evenly.

2. The Region or Climate Zone You Live In

Where you live in the country or even in your state can impact what kind of system capacity you need. If the weather tends to be consistently hotter in your climate zone, it’s essential that you take that into account when evaluating your home’s air conditioner size.

3. Your Home’s Doors, Windows, and Skylights

Doors, windows, and skylights can be responsible for substantial heat gain during the summer. You’ll need to factor in how many windows, doors, and skylights your home has and what type they are.

4. How Much Direct Sunlight Your Home Gets

Whereas some homes get a lot of shade from surrounding trees, others get direct sunlight throughout most of the day. If your home gets a lot of sunlight, it’s easier to overwork an undersized AC unit.

5. Your Home’s Existing Insulation

Your insulation is meant to keep heat in your home during winter and block heat from entering your home during summer. If your home’s insulation tends to underperform and you don’t plan to update it in the near future, you may need to consider a higher-capacity AC.


At Tri-City Heating and Cooling, we know that having the right air conditioner in your home makes all the difference in terms of comfort and energy savings. Call us today at (203) 303-5700 to schedule a quote for a new system with our friendly HVAC experts.