What Size Air Conditioner Do I Need for My Home?

When it comes to installing a new air conditioning system, choosing the right size is one of the most important steps. Homeowners often ask, “What size air conditioner do I need?” The answer depends on several factors including square footage, room function, ceiling height, and home insulation. At Galmiche & Sons, we help St. Louis homeowners make smart, efficient choices when it comes to cooling their homes.

To learn more about air conditioner sizing and for help selecting the best air conditioner for your St. Louis area home, contact our team today.

Why Air Conditioner Sizing Matters

Air conditioner sizing is critical to home comfort and energy efficiency. An AC unit that is too small will run constantly, trying to cool your space without ever reaching the desired temperature. On the other hand, oversized AC unit problems include short cycling, turning on and off frequently, which wears out components and fails to dehumidify properly.

The right-sized unit ensures even cooling, optimal humidity control, lower energy bills, and a longer system lifespan.

Square Footage Guidelines for AC Sizing

One of the most straightforward methods to estimate AC size is by calculating your home’s square footage. While a professional load calculation provides the most accurate recommendation, general guidelines can help you get a ballpark figure:

Square Footage	Recommended AC Size (BTUs)
600 – 1,000 sq. ft.	18,000 – 24,000 BTUs (1.5 – 2 tons)
1,000 – 1,500 sq. ft.	24,000 – 30,000 BTUs (2 – 2.5 tons)
1,500 – 2,000 sq. ft.	30,000 – 36,000 BTUs (2.5 – 3 tons)
2,000 – 2,500 sq. ft.	36,000 – 42,000 BTUs (3 – 3.5 tons)
2,500 – 3,000 sq. ft.	42,000 – 48,000 BTUs (3.5 – 4 tons)

Learn more about air conditioner sizing and BTUs

Room-by-Room Breakdown

When it comes to answering the question what size air conditioner do you need, different rooms in your home may require more or less cooling power based on their use and location. Here’s a closer look:

Living Room

Living rooms are often large, open spaces where families gather. With high foot traffic and potential heat from electronics or sunlight, this area may need a slightly larger AC zone or vent system.

Kitchen

Kitchens generate extra heat due to appliances. If your AC system does not account for this, the room can remain uncomfortably warm. Oversizing just the kitchen area or adding ventilation support may help.

Bedrooms

Bedrooms typically require consistent cooling for comfort during sleep. A properly sized system will ensure a comfortable temperature overnight without noise or energy waste.

Upper Floors

Heat rises, so upstairs rooms generally need more cooling. Homes in St. Louis with poor attic insulation especially benefit from enhanced sizing considerations on upper floors. This may consider adding a second unit for your upstairs or supplementing with ductless systems.

Factors That Affect AC Sizing

Beyond square footage, several other variables influence what size air conditioner you need:

Insulation Quality: Well-insulated homes retain cool air better and may require smaller systems.
Window Size & Placement: Large or south-facing windows let in more heat.
Ceiling Height: Homes with vaulted ceilings may need more BTUs to cool the increased air volume.
Home Layout: Open-concept homes often need strategic zoning or more powerful systems.
Climate: St. Louis summers are hot and humid, so selecting a unit that can also manage moisture is important.

How Galmiche & Sons Helps

At Galmiche & Sons, we use professional Manual J load calculations to determine the exact cooling needs for your St. Louis area home. We take all relevant factors into account and provide tailored recommendations that fit your comfort goals and budget.

We also help homeowners compare energy-efficient models, select appropriate zoning systems, and install with precision. Our team has decades of experience and a commitment to doing the job right.

FAQs

How do I calculate my home's square footage for AC sizing?

Measure the length and width of each room, multiply for the area, and add them all together. For multi-level homes, calculate each level separately.

Is a bigger air conditioner always better?

No. Oversized units can lead to short cycling, poor humidity control, and higher energy costs.

What is a Manual J calculation?

It is a detailed assessment of your home's heating and cooling needs based on square footage, layout, materials, and other key data.

Can I install the AC myself?

We strongly recommend hiring a licensed professional. Improper installation can result in poor performance, voided warranties, and safety risks.

What Size Air Conditioner Do You Need? Call Galmiche & Sons Today

Choosing the right air conditioner size is essential to comfort and cost savings. If you’re still wondering, “What size air conditioner do I need for my home?” let the experts at Galmiche & Sons help. We offer professional AC sizing and installation services to homeowners throughout the St. Louis area.

Contact our heating and air conditioning experts today to schedule a consultation or request an estimate.