SEER Rating Calculator: Easy-To-Use AC Running Costs Estimate

SEER rating should be the No. 1 factor when choosing an air conditioner. Higher SEER rated AC units can save you $1,000s over the next 10-20 years in electricity bill savings.

To see exactly much you can save by choosing an air conditioner with a higher SEER (above the federally mandated minimum of 14 SEER), you can use the SEER savings calculator below. First, however, let’s look at one example:

Example: We have two 3 ton (36,000 BTU) central air conditioners. One has a 14 SEER rating and the other has a 20 SEER rating. Let’s take into account the average natural electricity cost of $0.1319 per kWh, and 1000h of AC use per season.

How much more efficient is a 20 SEER vs 14 SEER?

Solution: 14 SEER rated AC unit is powered (average seasonal wattage) by 36,000 BTU / 14 SEER = 2,570W; running it for 1,000 hours will spend 2,570 kWh. Total 14 SEER electricity cost = 2,570 kWh * $0.1319 per kWh = $338,72/year.

20 SEER rated AC unit is powered by 36,000 BTU / 20 SEER = 1,800W; running it for 1,000 hours will spend 1,800 kWh. Total 20 SEER electricity cost = 1,800 kWh * $0.1319 per kWh = $237,24/year.

In short, 20 SEER AC unit is 43% more energy-efficient than 14 SEER AC unit. Here are the savings:

  • Per 1 year: $101,48 electricity savings.
  • Per 10 years: $1.014,80 electricity savings.
  • Per 20 years: $2.029,6 electricity savings.

You save about 7% per 1 SEER on electricity costs.

We will explain how do you calculate air conditioner SEER further on. You can use this handy SEER savings calculator to calculate how much electricity will an AC unit with a specified SEER rating and tonnage cost:

SEER Savings Calculator

Just input cooling capacity (in BTU; 1 ton = 12,000 BTU) and SEER rating:


*In the SEER savings calculator, we predispose 1000 running hours per season/year and $0.1319 kWh cost.

If you input 2 different SEER ratings, you can see how yearly electricity costs change accordingly. This calculator is often used as a mini-split energy consumption calculator; essentially you can use it as a mini split SEER savings calculator.

Mini-split example: How much does it cost to run an extremely energy-efficient 22 SEER rated 24,000 BTU ductless mini-split AC unit? Let’s use the SEER savings calculator to answer this:

how much more energy efficient is 21 seer rating mini split air conditioner

You can see that this 2 ton (24,000 BTU) ductless mini-split air conditioner costs less than $200 per year to run ($190/year to be exact).

You can freely use this SEER energy-savings calculator to calculate AC energy consumption for any unit with up to 5-ton capacity and SEER rating between 10 and 25.

How Do You Calculate Air Conditioner SEER?

The SEER rating is based on the EER rating. SEER stands for Seasonal Energy-Efficiency Ratio or Seasonal EER.

EER rating is simply calculated by dividing the cooling output (in BTU, or British Thermal Units) with the maximum power draw (wattage).

Example: 30,000 BTU AC units that have a maximum power input of 3,000 W have an EER rating of 10.

Calculation: EER = 30,000 BTU / 3,000 W = 10.

To calculate SEER from EER rating, we have to use this SEER equation:

SEER = (1 × EER100% + 42 × EER75% + 45 × EER50% + 12 × EER25%) / 100

This calculation is done by HVAC engineers; we only have EER100%. To properly calculate SEER, engineers have to measure EER50%, EER75%, and EER25% experimentally.

In general, the easiest way to calculate SEER based on only EER100%, is by using this formula:

SEER = (1.12 – √(1.2544 – 0.08*EER100%)) / 0.04

Alternatively, you can use this EER to SEER calculator that uses this exact formula.

How Much Money Do You Save Per SEER?

There is no absolute figure how much you save per 1 SEER rating. It’s a relative savings calculation that must include 2 units with 1 SEER difference. Let’s look at some examples:

  • 15 SEER vs 16 SEER: You save (16/15 – 1) * 100% = 6,67% savings per SEER.
  • 16 SEER vs 17 SEER: You save (17/16 – 1) * 100% = 6,25% savings per SEER.
  • 17 SEER vs 18 SEER: You save (18/17 – 1) * 100% = 5,88% savings per SEER.
  • 20 SEER vs 21 SEER: You save (21/20 – 1) * 100% = 5,00% savings per SEER.
  • 22 SEER vs 23 SEER: You save (22/21 – 1) * 100% = 4,54% savings per SEER.

We can also calculate how much more energy-efficient are AC units that have a difference in SEER rating greater than 1:

  • 14 SEER vs 16 SEER: You save (16/14 – 1) * 100% = 14,3% electricity savings.
  • 16 SEER vs 18 SEER: You save (18/16 – 1) * 100% = 12,3% electricity savings.
  • 18 SEER vs 20 SEER: You save (20/18 – 1) * 100% = 11,1% electricity savings.
  • 20 SEER vs 22 SEER: You save (22/20 – 1) * 100% = 10,0% electricity savings.
  • 14 SEER vs 18 SEER: You save (18/14 – 1) * 100% = 28,6% electricity savings.
  • 14 SEER vs 20 SEER: You save (20/14 – 1) * 100% = 42,9% electricity savings.
  • 16 SEER vs 20 SEER: You save (20/16 – 1) * 100% = 25,0% electricity savings.

The key question that the AC SEER cost calculator can help you answer is of this kind:

Is 21 SEER worth the money?

How Much Less Do You Pay For Electricity If You Choose A Higher SEER Rating AC?

Let’s say that we’re looking at a 21 SEER vs 16 SEER unit; both have the 3-ton capacity and are pretty much the same in all regards, apart from energy-efficiency.

16 SEER unit costs $500 less than 21 SEER unit; should you buy the 16 SEER unit or is the 21 SEER unit worth the money?

Let’s use the SEER electricity cost calculator above to answer this riddle:

21 SEER 3 ton unit costs about $298/year to run.

16 SEER 3 ton unit costs about $392/year to run.

That’s a rough difference of about $100 per year. In 10 years, the 21 SEER rated unit will use $1,000 less electricity, and in 20 years – the lifespan of a mini-split AC unit – it will use $2,000 less electricity.

Answer: Even though the 16 SEER unit costs $500 more, the 21 SEER unit is a better choice. In 20 years, the net savings you get by choosing the pricier 21 SEER unit are $1,500.

Takeaway: Higher SEER Rated Units Are Financially A Better Choice

As you can see in numerous cases, it almost always makes financial sense to choose an AC unit – especially the central air conditioners with up to 5-ton cooling capacity – with a higher SEER rating.

The unit cost of lower SEER rating air conditioners might be lower. But, if you include the future electricity costs, the total cost of an air conditioner will almost always be lower if you choose higher SEER rating units.

On top of that, higher SEER units are also more environmentally friendly; we will have to use less coal, gas, and so on, to produce electricity your AC uses.

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