What Is SEER? (2024 Guide)

By Cristy Lynch Updated February 6, 2024

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SEER stands for seasonal energy efficiency ratio. Essentially, it’s a measure of an air conditioner’s maximum energy efficiency over a typical cooling season. The higher the SEER rating, the more efficient the AC unit.

This guide breaks down everything you need to know about the SEER system to find the best AC for your needs, including how this rating is calculated and the standard for high-efficiency systems.



Benefits of a High SEER Rating

Choosing a high-efficiency air conditioner provides numerous benefits. Here are some of the highlights.

Energy Savings

Though high-efficiency air conditioners cost more up-front, you’ll save money on utility bills long-term. You can estimate your savings by comparing your new unit’s SEER rating to the old unit’s rating and factoring in the price of energy per kilowatt-hour in your area. Several online savings calculators can do the math for you.

Less Noise

High-efficiency ACs are generally quieter than low-efficiency ones. This is especially true for the condenser unit, or the portion of a split system that sits outside. Noise may become a problem if the condenser is located next to a bedroom window.

Reduced Environmental Impact

Unless you get your energy from a renewable source such as wind or solar energy, creating electricity requires burning fossil fuels, which puts carbon and pollutants into the atmosphere. Air conditioners use a great deal of electricity, but high-efficiency options need less energy to run, reducing your personal environmental impact.

Tax Credits and Rebates

The government offers a federal tax credit to homeowners who install Energy Star-certified central air conditioners with a SEER2 rating of at least 16. You can receive a credit equal to 30% of your installation costs up to $600. Some local energy partners may offer additional rebates.



What’s the Difference Between SEER and SEER2?

The SEER system has been in place since 1992. However, critics pointed out that it didn’t take into account how ductwork and external static pressure affect efficiency. A new set of efficiency standards, called SEER2, is designed to more accurately measure system efficiency in real-world conditions.

As of January 2024, all new heating, ventilation, and air conditioning (HVAC) systems will have a SEER2 rating. New products may be marked with both a SEER and SEER2 rating for a few years. The SEER2 rating is 4.5% lower than SEER to account for energy leakage in air ducts. For example, a unit with a SEER of 15 will typically have a SEER2 of 14.3. The federal tax credit is determined based on the SEER2 rating.



What’s the Difference Between SEER and EER?

The efficiency of window and portable air conditioning units is typically measured as EER rather than SEER. The difference is that SEER measures a system’s average efficiency over an entire cooling season, whereas EER measures efficiency under specific testing conditions. Because smaller, single-room AC units are less affected by environmental conditions than central cooling systems, EER is a more appropriate measure of efficiency for them.



Determining a Good SEER Rating

As of 2024, the U.S. Department of Energy requires that central AC systems have a minimum SEER rating of 15 in the Southeast and Southwest and 14 in all northern states. Older AC units may have SEER ratings of 9 to 13. A good SEER rating is generally considered to be anything 16 or above. Traditional central air conditioners can have SEER ratings of up to 26, and extremely efficient systems such as heat pumps and ductless mini-split systems can have a rating in the 30s or 40s.

SEER is calculated by dividing the total number of British thermal units (BTUs) of heat an AC removes from the air by the total watt-hours of energy it needs to run. It takes roughly 5,000 BTUs to cool a room of 150 square feet. The size air conditioner you need depends on factors such as your ceiling height and local climate, but most central AC systems put out between 18,000 and 60,000 BTUs.

SEER Ratings Chart

AC installation costs are determined in part by efficiency, as more efficient models are typically more expensive. Here are some sample costs for a typical 3-ton, 36,000-BTU central air conditioner.

SEER RatingSystem Size in TonsCost Range*
















*Cost ranges via Angi.

Where to Find SEER Ratings

When comparing air conditioners, look for a yellow and black EnergyGuide label. Not all appliances have this sticker, but most HVAC units do. The SEER and SEER2 ratings will be clearly labeled. You’ll also find information such as the maker, model number, unit size, estimated yearly energy consumption, and estimated yearly operating cost compared to similar models. Any product that has an Energy Star logo exceeds the federal minimum standards for efficiency and quality.



What Makes an Air Conditioner High Efficiency?

Air conditioners with SEER ratings between 14 and 16 use the same basic technology. AC units with a SEER rating of 17 and above use a different type of compressor and condenser fan to achieve maximum efficiency. Traditional, regular-efficiency AC units have two speeds: on and off. The system remains on until the temperature set by the thermostat is achieved, and then it turns off. 

High-efficiency systems use two-speed or variable compressors and variable condenser fans. These parts run at lower speeds when possible, using less overall electricity and creating less noise. Essentially, the air conditioner doesn’t have to work as hard to keep your home cool. These parts are more expensive and a bit more difficult to repair than traditional AC parts.



Our Recommendation

It’s important to consider efficiency when shopping for a new air conditioner. Invest in a system with a SEER2 rating of at least 16 when possible. These high-efficiency systems cost more up-front, but you’ll qualify for a federal tax credit and save money on your energy bills over time. As outdoor temperatures climb each summer, you can feel good about keeping your indoor temperature at a comfortable level with minimal electricity.

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What is the minimum allowable SEER rating for a federal tax credit?

The minimum SEER2 rating for an AC to qualify for a federal tax credit is 16.

How much more efficient is a 16 SEER versus 14 SEER?

A 16-SEER unit is about 13% to 14% more efficient than a 14-SEER unit. These are two of the most common SEER ratings for residential air conditioners.

Why is SEER rating important?

An air conditioner’s SEER rating is important because it measures the unit’s efficiency. The more efficient a cooling system is, the less money you’ll pay on your electricity bill. 

Is 16 SEER considered high efficiency?

Yes, a SEER rating of 16 is considered high efficiency, but some systems can have ratings much higher than that. Central air conditioners can go up to 26, and heat pumps can be in the 30s or 40s.

Is SEER 21 worth the investment?

When determining what SEER rating is best for you, you’ll need to balance up-front costs with long-term energy savings. A 21-SEER air conditioner is considered very high efficiency, and it can save you about 33% on your utility bills compared to a 14-SEER unit. However, it will cost approximately $4,600 to $7,200 more up-front.