You’ve decided to bring in an additional air conditioner to help keep your home cooler. Or, perhaps you’ve just built a new house. Now it’s time to install air conditioning.

So, while shopping around, you come across “SEER” ratings. Now you’re wondering which is the best SEER rating for air conditions. Perhaps you’ve even done some research and concluded that you need either a 13 SEER or a 16 SEER air conditioner. Now you’re wondering which is the right choice.

This short guide should help you understand SEER ratings better and determine the best choice for your needs.

## What are SEER Ratings?

The best place to start is with a definition. SEER ratings are a way to rate air conditioner efficiency. The term stands for Seasonal Energy Efficiency Ratio. The “R” may also stand for rating, depending on where you’re reading.

Generally, though, the SEER rating is the ratio of the cooling output of an air conditioner over a typical air conditioning season, divided by the energy it consumes in Watt-Hours over the same period. In simple terms, it’s like asking, “how much energy does the AC in question consume for every BTU of heat it removes during the cooling season?”

The SEER value is calculated over an entire heating season. Therefore, it’s an average value. It’s also calculated at a constant indoor temperature. Outdoor temperatures aren’t critical to the math and may range from 60°F to 100°F without adverse consequences.

## Calculating SEER Ratings

If you’d like to know how to calculate SEER ratings, it’s not rocket science. Of course, you can quickly check your AC label to determine the SEER rating. However, you may want to verify whether the value is accurate. Here’s how to proceed;

**Determine your AC BTU rating**: This value is typically indicated on the product label or in the manufacturer’s manual, though you’ll often find it in both. It’s the size of your air conditioner, which tells you how much heat the air conditioner removes per unit time, typically per hour.**Determine the value of watts hours**: This value can also be found on the product label. It tells you how many watts the air conditioner consumes for every hour that it’s running. If it’s not on the label, check the owner’s manual.**Determine the number of BTUs removed per month**: Now that you know how many BTUs the air conditioner removes per hour (from step #1), it’s easy to determine how many BTUs it would remove over the entire heating season. Multiply the hourly heat removal rate by the number of hours the AC runs in a typical cooling season. The industry average is 125 days, equivalent to 1,000 hours. So, multiply the number in #1 by 1,000.**Calculate total watt-hours consumed for the cooling season**: This should also be pretty easy. All you need to do is multiply the watt-hours consumed (per hour) by the number of cooling hours in a year (1,000).**Divide the value of BTUs by total Watt Hours**: It’s essentially the value of #3 divide by the value of #4. This value should give you the SEER rating of the air conditioner.

## 13 SEER vs. 16 SEER Ratings

Working backward, it’s easy to determine what you get with a 13 SEER air conditioner compared to a 16 SEER unit.

For example, if we assume that you’re only interested in an 18,000 BTU air conditioner, it’s easy to determine how many watt-hours the unit would consume.

A 13 SEER, 18,000 BTU air conditioner consumes 18,000 /13 = 1,384.6 watts/hour whereas a 16 SEER, 18,000 BTU air conditioner consumes 18,000/16 = 1,125 watts per hour.

So, as you can see, if you’re going for an 18,000 BTU air conditioner, a 16 SEER unit consumes fewer watts per hour than a 13 SEER model. The difference between the two is 1,384.6 – 1,125 = 259.6 watts.

Let’s try a higher-sized air conditioner, say 48,000 BTU. A 13 SEER, 48,000 BTU air conditioner consumes 48,000/13 = 3,692.3 watts per hour, while a similarly sized rated 16 SEER consumes 3,000 watts per hour.

Here again, you can see that a 16 SEER air conditioner consumes fewer watts than a 13 SEER air conditioner. However, this time the difference is slightly here at 3,692.3 – 3,000 = 692.3 watts. So we can round it off to 692 watts.

## Does it Make a Difference?

Yes, and that’s the reason you keep seeing debates on SEER ratings online and offline. Every extra watt the AC consumes hurts your pocket. So, if you get the chance to save over 600 watts, you’re also saving a lot of money.

Here’s a better breakdown;

The average cost of electricity in the US is 13.76 cents/kilowatt-hour (1,000 watts). This translates to $0.1376/kilowatt-hour.

Now, imagine that you’ve settled on an 18,000 BTU window air conditioner for your living room. However, you have two options, a 13 SEER unit or a 16 SEER unit.

We’ve already established that a 13-SEER, 18,000 BTU air conditioner consumes 1,384.6 watts per hour, equivalent to 1.3846 kilowatts per hour. Meanwhile, a similarly-sized unit rated 16 SEER consumes 1.125 watts per hour, translating to 1.125 kilowatts per hour.

So, how much does it cost to run each AC per hour, per day, and over a cooling season in the entire year? Assuming that you run the AC for eight hours per day, the industry average, you’d spend the following amounts.

For the 13 SEER unit;

- Per hour = 1.3846 x $0.1376 = $0.1905/hour
- Per day = $0.1905/hour x 24 hours = $1.5241/day
- Per season = $1.5241/day x 125 days = $190.55207/year

Meanwhile, for the 16 SEER unit;

- Per hour = 1.125 x $0.1376 = $0.1548/hour
- Per day = $0.1548/hour x 8 hours = $1.2384/day
- Per season = $1.2384/day x 125 days = $154.8/year

So, as you can see, the difference may seem small when you’re looking at the hourly variance. However, it grows significantly when you project it over an entire cooling season. In this case, you’d end up spending about $35.75 more per season if you opt for a 13 SEER air conditioner over a 16 SEER model, assuming that you’re shopping for an 18,000 BTU air conditioner.

Now, imagine the difference for larger air conditioners. It may run into hundreds of dollars over a cooling season. If you extrapolate the figure for the life of the air conditions, which is about 20 years, it runs into thousands of dollars. Even for the 18,000 BTU air conditioner, the difference in running the two ACs (one at 13 SEER and the other at 16 SEER) is about $715.

Imagine what you could do with an extra $714 today! It’s a lot, right. You’d even purchase a new wall air conditioner with the $714.

## Verdict

The difference between a 13 SEER air conditioner and 16 SEER air conditioners is massive. This is especially true for larger-size air conditioners. You’re looking at losses exceeding $1,000 for a 36,000 BTU air conditioner and more for higher-sized units.

So, although the decision is still in your hands, it would be a lot more cost-effective to invest in a 16 SEER air conditioner than a 13 SEER option.