What Is Seer Rating (Plus How to Buy for Your Next AC)

Buying a new air conditioner can be a challenge. There are a lot of top AC brands out there to choose from. On top of that, you also have to get the right model for your climate, region, and size factors. If you are looking for tax rebates, savings, and performance, that is another set of considerations.

One of the biggest factors, though, is the SEER rating. This article will explain what a SEER rating is, what it means to you and how it can help you find the best air conditioner for your specific needs.

What Is SEER on an AC?

SEER is a rating system that explains in smaller numbers how efficient that system is. The US Department of Energy has mandated that air conditioners meet minimum efficiency ratings, and thus, the energy guide was born. Legislation that began in 1987 went into effect with a minimum SEER rating of 10 for all central ACs in 1992.

SEER stands for Seasonal Energy Efficiency Ratio, and it is the ratio between the electrical wattage input of the system versus the BTU output of the air conditioner. The higher the SEER rating, the more efficient that system is, which in turn means it costs less to operate during the warmer months.

As of 2006, central air conditioners minimum was raised by the DoE to 13 SEER. There are also minimum standards for SEER ratings depending on where you live, such as a minimum 14.5 SEER rating in the south and 14 SEER in the southwest.

Related Article Wattage Vs BTU Output?


Why SEER Ratings Matter?

SEER ratings are more than just a yellow sticker on the side of your air conditioner. These numbers are important when shopping for the best air conditioner for your home. Aside from the minimum mentioned above, SEER ratings tell you a lot about the unit.

For starters, they can help you determine how much you can expect to pay, per year, in energy costs. This allows you to compare similar units based on post-install costs and monthly energy bill increases.

Keep in mind, though, that the SEER rating is compiled using a standardized test with a set formula. There are variables to consider, like the amount of insulation in the home, ducting, and average temperatures in your area. When looking at the SEER, expect about 10 – 15% energy loss (higher cost) compared to what is on the sticker.

While higher SEER ratings are generally worth the investment, it will take some time for those higher numbers to be a factor on your bill. Just because you buy a 20 SEER air conditioner doesn’t mean it will cost less to run each month compared to a 17 SEER model.

Related Article Top Central Air Conditioners

Benefits of Higher SEER Ratings for Your AC

As mentioned earlier, higher SEER ratings are generally a benefit. This will depend a lot on how high your temperatures get during the summer and how often the air conditioner is running per day.

Northern states that run an air conditioner fewer hours per day and fewer days per year won’t see as many benefits from a higher SEER rating as you would in the south, with higher temperatures for more days. The benefits, though, are compelling. Take a look.

Lower Electricity Bills

The first thing to note is energy consumption. Higher SEER-rated machines use less energy to operate, which will translate to lower energy bills each month.

In contrast, those with much higher SEER ratings (19+) will need to run for several hours per day (8+ minimum) to see the cost savings.

seer rating chart
Great Humidity Control

Larger capacity air conditioners need variable speed fans and compressors to keep the refrigerant moving and removing heat. This also translates into more humidity being removed. High SEER units have multi-speed fans and compressors, allowing them to take a larger role in humidity control.

Less Noise Function

Because technology requires that SEER values keep going up, more efficient systems are being built each day. This means a massive drop in noise levels, too. Since compressors and fans now operate on multi-speed and variable speed technologies, they don’t produce as much noise. Some brands see a drop of over 20dB with higher SEER units compared to their lower SEER counterparts.

More Environmentally Friendly

By using less electricity, you also help the environment. While it may not be a direct correlation, over time, higher SEER appliances, air conditioners, and other systems will reduce carbon emissions, require less energy and take a major strain off existing networks and systems.

Better Air Circulation

Improved efficiency also directly translates into improved airflow. When the system is working with less effort, it produces less heat. This means it spends less time cooling the air and more time moving it around. With high SEER air conditioners, you will notice they run less often, for shorter times, and the indoor air quality and circulation are improved.

Media Filters for Better Filtration

In line with better indoor air quality, higher SEER units also use better filtration methods. Media filters can capture more particles like smoke, odors, and even bacteria and viruses. These things used to make their way into the system, eventually causing problems or bad air quality. A more efficient machine will run longer with fewer pollutants, and the filters help with that.

Where to Find Your AC’s SEER Rating

Locating the SEER rating isn’t difficult. Primarily you will locate the SEER rating tag and energy guide on the packaging of the unit, price tag in the store, or posted directly on the unit itself.

This energy guide sticker may give you the model information, unit type, SEER rating, EER rating, HSPF rating, and expected annual running costs.

You can also find the SEER rating on the brand website in the model product description or the online specifications sheets linked to the product page.

If none of these options are available, you can also get the SEER information by calling or emailing the brand’s customer service representatives.

Many brand websites have contact information pages, including live chat features, to get faster answers.

See our related articles for more information:

How to Calculate Your AC’s SEER Rating

If you want to calculate the SEER rating of your current air conditioner or a new one where the energy guide sticker is not available, there are methods to do that. Keep in mind that any manual formulas used are only going to get a rough estimate.

The actual mathematical formula for SEER and EER ratings is quite complex and has a lot of variables. We can, however, get you close enough for comfort using the following steps.

  1. .Essentially a SEER rating is the numerical ratio of watts input and BTU output. So your first step is to find the BTU output of the device. You can use exact numbers if they are known, or use the numbers based on air conditioner tonnage (see further below).
  2. .Next, find the watts used per hour of your air conditioner. This can be found on the documentation, information plate, or on the brand’s website. If the wattage is not listed, multiply the voltage and amps together to get the watts.
  3. .SEER is a seasonal number, and for air conditioners, that season is summer. Therefore you need to determine how many days of summer you are calculating for. Most SEER ratings use 125 days, but colder climates and northern regions may go as low as 90.
  4. .Now you need to calculate the watt-hours (wH) used by your machine. Simply take the watts from above and multiply by 1000. The result will be the number needed for the ratio.
  5. .Next, calculate the BTU-hours for the ratio by multiplying the BTU output from above by the number of summer hours you are calculating for (1000 for 125 days at 8 hours per day, or 720 for 90 days).
  6. .Finally, divide the BTU hours by the watt-hours to get your SEER rating estimate.

Seer Rating Charts

With so many different options, sizes, SEER values, and nation-wide energy costs, it is almost impossible to list every combination available. However, we can make educated guesses based on national averages, such as the cost of electricity at 13 cents ($0.136 as of Jan 2021) per kilowatt hour (kWh).

Note that the EER and SEER ratings are different. SEER ratings are higher because they use only a portion of the year for the average rating. EER ratings use the entire year and produce a smaller average. As you can see below, though, the two ratings do correlate to each other.

EER RatingSEER rating

How, then, do the costs compare to the SEER ratings? In short, the higher the SEER value, the less it will cost to run the system per year. This directly correlates to a lower monthly energy bill the higher the SEER value goes.

If your system is old, it is most likely a 10 SEER (or even lower). If this is the case, it is time to upgrade. But what SEER rating should your new unit have? That answer will depend on several factors.

First, you want to look at the unit cost of the new air conditioner. How much will this cost you to purchase and install?

Next, you want to determine the cost savings between your current air conditioner and the new one. For example, if your current system costs you $315 to run and the new unit will cost $175, that is an annual savings of $140.

Assuming you will own the new system for 20 years, that is a total savings of $2800. If your new unit costs less than $2800, then you have a great deal on your hands.

Finding your exact savings will depend on current SEER ratings versus the SEER of your new air conditioner, how often it runs, how many days you calculate for each year, changes in temperature, and several other factors.

Below, we have compiled a chart comparing various SEER values as a general guide. Of course, you can use the SEER rating calculator above to get more accurate numbers for your particular setup.

This chart assumes a 2.5-ton air conditioner, running 1000 hours at the cost of 13.6 cents per kWh.

Comparing SEERs1st SEER Cost2nd SEER Cost1-Year Savings10-Year Savings
10 vs. 13$408$314$94$940
10 vs. 14$408$291$117$1170
10 vs. 15$408$272$136$1360
10 vs. 16$408$255$153$1530
10 vs. 18$408$227$181$1890
10 vs. 20$408$204$204$2040
13 vs. 14$314$291$23$230
13 vs. 15$314$272$42$420
13 vs. 16$314$255$59$590
13 vs. 18$314$227$87$870
13 vs. 20$314$204$110$1100
14 vs. 15$291$272$19$190
14 vs. 16$291$255$36$360
14 vs. 18$291$227$64$640
14 vs. 20$291$204$87$870
15 vs. 16$272$255$17$170
15 vs. 18$272$227$45$450
15 vs. 20$272$204$68$680
16 vs. 18$255$227$28$280
16 vs. 20$255$204$51$510
18 vs. 20$227$204$23$230

SEER Ratings Per AC Based on Size

Your system’s size will determine how much it costs you to operate based on the SEER values, which is why it’s important to get the right size AC unit. Larger units use more electricity and output more BTUs. A BTU is a British Thermal Unit and is a metric used to determine performance.

For air conditioners, each ton represents a specific amount of BTUs. 12,000 BTUs is equal to 1 ton and is the standard measurement of how much energy it takes to melt 1 ton of ice in 1 full day. The higher the output means more energy consumption, but the higher SEER value also means less running costs for you. We break it down by AC size below.

Related Article What Size AC Should I Get?

2 Ton AC Unit /24,000 BTU

A 2-ton unit has an output of 24,000 BTUs. The SEER value for a 2-ton unit will determine how much it costs to operate during the warm summer months.

For example, a 2-ton unit with a SEER rating of 10 would cost you about $326 per year. That same size AC with a SEER rating of 16 would cost only $204 per year to operate.

How many BTU in a Ton? Learn here

3 Ton AC Unit /36000 BTU

A 3-ton unit then produces an output of 36,000 BTU. Various SEER ratings will have different costs, but they will be higher than a 2-ton unit. Because the output is higher, the SEER values are averaged differently.

For example, a 3-ton unit with a 16 SEER rating costs $306 per year, compared to the same SEER of a 2-ton unit which costs $204. However, running a 2-ton unit when your space and size requirements ask for a 3-ton size will drastically increase the cost of running that 2-ton unit to well over $400 per year.

4 Ton AC Unit /48000 BTU

A 4-ton AC pushes out 48,000 BTUs and has a much higher cost to operate per year than a 3- or 2-ton unit. Again, though, if your space requires 4-ton air conditioning, it is much cheaper to purchase a single 4-ton model than two 2-ton models.

A 4-ton unit with a SEER rating of 16 should cost about $408 per year. While this is the same cost and output as buying or using two 2-ton units, the unit and installation costs are reduced by thousands of dollars.

5 Ton AC Unit/60000 BTU

5-ton models are about as high as residential air conditioners go. With an output of 60,000 BTU, 5-ton models are designed for large spaces and homes with at least 2500 square feet but cover up to about 3800 square feet with ease.

To compare again, a 5-ton AC with a 16 SEER rating will cost about $510 to operate per year.

People Also Ask (FAQ)

What is the most common SEER rating for an air conditioner?

All brands manufacture air conditioner units in various SEER ratings. The most common SEER value will vary based on state, region, and climate. The most common SEER ratings fall between 13 and 21 SEER, with 16 SEER considered good and 19+ SEER considered great. However, 14.5 SEER and higher units are recommended for southern states.

Does a higher SEER cool better?

A high SEER air conditioner doesn’t produce more or better cold air. What it does do, though, is run less often and less frequently. SEER ratings determine how much the unit will cost to run and how energy efficient they are in doing so. However, it is not an indication of how well the system performs, although it can be used as an indication.

What is the minimum SEER rating for Energy Star?

To qualify as an Energy Star product, the air conditioner must have a minimum SEER rating of 14.5 and an EER rating of 12.0 (central split systems). If these minimums are not met, the unit cannot be Energy Star certified.

Do heat pumps use the same metric for SEER?

Yes, heat pumps use the same formulas and metrics for SEER ratings. However, because they only cool in one direction, the SEER rating is only used to establish efficiency when in cooling mode. The heat pump should also list the HSPF rating (Heating Seasonal Performance Factor) for the heating efficiency rating along with the SEER.

What is EER and how is it different?

EER is the Energy Efficiency Ratio and determines the cost of running the unit over the course of an entire year. Compared to a SEER rating, which only calculates efficiency and running costs during the summer months, the EER determines the actual efficiency of the unit during optimal and average temperatures over 12 months.


SEER ratings are designed to show you how efficient an air conditioner is over the course of the hotter months when the unit will be used the most. Higher SEER ratings mean more efficient machines and a lower annual cost of operation.

Purchasing an air conditioner based on SEER values alone is not recommended. However, it is a great indication of potential savings, model and operational costs, and gives you a place to start your budgeting.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.