What Size Air Conditioner is Best for Arizona?

Choosing the right air conditioner for your home is a decision that will affect your comfort for years to come. Since we run our air conditioners continuously for months during Arizona’s brutally hot summers, having an air conditioner that’s the wrong size for your home can impact your comfort, energy bills, and even your health.

Before choosing an air conditioner, it’s helpful to know how A/C units are sized and their efficiency rating.

Understanding BTUs

The capacity of an air conditioner to cool a space is measured in British Thermal Units, known as BTUs.

BTUs are a measurement of heat energy. When applying BTU specifications to an air conditioner, the BTU number refers to the amount of heat the air conditioner can remove from the air in one hour.

However, a bigger air conditioner with more cooling capacity isn’t necessarily better when choosing the best air conditioner for your home.

If you purchase an air conditioner that’s too large for your home, you’ll not only spend more for the unit; the compressor will turn on and off more than it should, leading to higher operating costs and more wear and tear on the system.

A unit that’s too large also won’t remove as much humidity from the air as a correctly sized air conditioner.

Purchasing an air conditioner that’s too small for your home will not keep it cool enough on the hottest days of summer. So choosing the correct size A/C unit is essential.

BTU ratings for residential air conditioning systems generally range from 12,000-60,000 BTUs. Your home’s floor plan, layout, ceiling height, and the number of stories all factor into the number of BTUs your air conditioner should have.

The direction your home faces and how well insulated it is are also considerations in determining the number of BTUs for your air conditioner. A west-facing house may require more BTUs than a north-facing house that sits in the shade.

As a general estimate of BTU requirements, a 1,500-2,000 square foot home needs an air conditioner with 30,000 BTUs, and a home of 2,000-2,400 square feet requires a unit with 34,000 BTUs.

HVAC pros use what’s known as the Manual J Load Calculation, which considers your home’s size, layout, and other factors to determine what size air conditioner is best for your home.

Tonnage is a measurement also used for central air conditioners, and it refers to cooling capacity, not weight. One ton is equivalent to 12,000 BTUs cooling capacity for an A/C unit.

It’s best to consult an HVAC professional for guidance in choosing the best air conditioner for your home. The experienced pros at Chas Roberts can help you choose the best air conditioner to keep you cool all summer long.

Energy Efficiency

Today’s air conditioners are far more energy-efficient than air conditioners of the past.

According to the U.S. Department of Energy, the most efficient air conditioners use 30-50% less energy to produce the same amount of cooling as air conditioners of the 1970s. You could even save 20-40% of cooling costs by replacing a ten-year-old A/C unit with a new, more efficient model.

In Arizona, where we run our air conditioners non-stop during the hottest months, you could see significant savings in energy costs by purchasing an energy-efficient unit.

The Seasonal Energy Efficiency Ratio, known as SEER, indicates an air conditioner’s efficiency and performance. The SEER rating shows how much energy an air conditioner will use in a year.

The higher the SEER, the less energy the air conditioner will use for cooling.

SEER ratings separate cooling systems into three categories:

  • Baseline efficiency: 13-16 SEER
  • Mid-efficiency: 16-18 SEER
  • High-efficiency: 20+ SEER

The Department of Energy has set standards for air conditioners sold in Arizona and other states with long, hot summers at a minimum SEER rating of 14.

Any new air conditioner you buy now will have a SEER rating of at least 14. As of January 2023, the minimum SEER rating for air conditioners sold in Arizona will rise to 15.

According to the Department of Energy, the new higher standards will save U.S. homeowners $2.5 billion to $12.5 billion in energy costs between 2023 and 2052.

If your current air conditioner is more than a few years old, a new 14 SEER unit may be far more energy-efficient than what you have now.  A 16 SEER unit could save you even more, although the upfront cost generally increases for air conditioners with a higher SEER rating.

According to the Kobie SEER Energy Savings Calculator, a 16 SEER air conditioner uses about 13% less energy to produce the same amount of cooling as a 14 SEER unit.

Unlike 14 SEER units, air conditioners rated 16 SEER and higher often have two-stage compressors, which allows them to adapt to conditions in your home. A two-stage compressor allows for longer run times and can keep the temperature in your home more consistent.

A 14 SEER air conditioner either runs at full speed or shuts off, while a higher SEER unit with a two-stage compressor can run at low speed, reduce your home’s humidity more, and be quieter.

You may also be able to receive a federal tax credit with a minimum 16 SEER-rated split system air conditioner.

These are all factors you should consider when purchasing a new air conditioner.

Energy Star Ratings

Energy Star air conditioning systems meet or exceed EPA energy requirements and must have a SEER rating of 15 or higher.

Energy Star is a government-backed system for energy efficiency. Products with the Energy Star label are more energy-efficient, help protect the environment, and can save you money in energy costs.

Energy Star air conditioners are 15% more efficient than standard models, according to the energy.gov website, so they’re worth considering for maximum energy savings.


Your thermostat is the control center for your air conditioner, and having a new A/C system installed is an ideal time to have a new thermostat installed.

The U.S. Department of Energy states that you can save as much as 10% on your energy bills by installing a programmable thermostat, so if you still have a manual thermostat, it’s time to upgrade.

A programmable thermostat can reduce your air conditioner’s run time, as you have precise temperature control throughout the day.  You’ll save money in energy costs and reduce wear and tear on your A/C system.

Chas Roberts can assist you in selecting a new programmable thermostat while helping you choose a new air conditioner for your home.


Size is only one factor to consider when choosing a new air conditioner for your home.  In Arizona, you also need maximum energy efficiency for the most savings possible on your summer energy costs.

Consult an experienced Chas Roberts HVAC professional for help in choosing the best air conditioning system for your home.

Family-owned and operated Chas Roberts is the largest HVAC company in Arizona and has been in business for over 75 years. Contact us for affordable, reliable service.