The electrical current (measured in Amperes or ‘amps‘ for short) needed to run an air conditioner is directly proportional to how much the AC unit will affect your electricity bill.
In most cases, people are interested in how many amps does a 5,000 BTU air conditioner use. Of course, you also have 6,000, 8,000, 12,000, 15,000, and 18,000 BTU devices that use more amps than 5,000 BTU units.
Here is a table of how many amps do different sizes of air conditioners (in BTU) draw. Below the table, you will find what factors determine the number of amps needed and how you can calculate how many amps your air conditioner uses.
Table: How Many Amps Do Air Conditioners Draw (5,000 BTU To 18,000 BTU Window And Portable Units)
|Air Conditioner Capacity||Amperage (Estimate)|
|5,000 BTU||3.62 – 5.43 Amps|
|6,000 BTU||4.35 – 6.52 Amps|
|8,000 BTU||5.80 – 8.70 Amps|
|10,000 BTU||7.25 – 10.87 Amps|
|12,000 BTU||8.70 – 13.04 Amps|
|15,000 BTU||10.87 – 16.30 Amps|
|18,000 BTU||13.04 – 19.57 Amps|
From the table above, it’s evident that window and portable air conditioners can draw anywhere from 3.52 amps to almost 20 amps.
How To Calculate The Number Of Amps An Air Conditioner Needs?
Usually, we size air conditioners based on capacity (measure in British Thermal Units or BTU for short). You can see how the size of AC units is calculated based primarily on square footage here.
If we want to know how many amps does an AC draw, we have to calculate in two steps:
- From BTU to electrical power (measured in Watts).
- From Watts to electrical current (measured in Amps).
To achieve this, we can use the following two equations:
Air conditioner capacity (BTU) = EER/P (in Watts) (Equation 1)
EER is Energy-Efficiency Rating that you can usually find in specification sheets of 5,000-18,000 BTU AC units. On average, EER ranges from 8 to 12. These numbers are also used to calculate the Amps intervals in the table above).
P (in Watts) = V (in Volts) * I (in Amps) (Equation 2)
The power of any electrical device is calculated by multiplying voltage with amperage. A great majority of AC units up to 15,000 BTU are powered by 115V voltage. Hence, if we know P (Power in Watts which we have calculated with Equation 1), we can calculate how many amps an air conditioner needs by merging the two equations, as such:
I (in Amps) = Air conditioner capacity (BTU) / (EER x V (in Volts)
Example 1: 5,000 BTU Window AC With EER 10
Let’s take a small 5,000 BTU unit with EER 10. We also know that the electrical potential in the outlet is 115V. Here is how we calculate the amps required to power the unit:
I (in Amps) = 5,000 BTU / (10 x 115V) = 4.35 Amps
The higher the energy-efficiency of the air conditioner, the fewer amps it will draw. Hence, we’ll pay less for electricity and still get the 5,000 BTU of cooling power. The most energy-efficient window air units have an EER rating above 11. You can check out the best window AC units here.
Example 2: 10,000 BTU Portable Air Conditioner With EER 12
The most efficient portable air conditioner can reach an EER rating of 12 or even more. For this example, let’s take a 10,000 BTU portable AC with EER 12 and powered by 115. Here’s how we can calculate how many amps such 10,000 BTU air conditioner draws:
I (in Amps) = 10,000 BTU / (12 x 115V) = 7.25 Amps
We see that this AC unit uses 7.25 amps in order to deliver 10,000 BTU of cooling power. Comparatively, the 5,000 BTU AC unit from Example 1 delivers 5,000 BTU of cooling power using 4.35 amps.
The higher energy-efficiency device from Example 2 (12 EER) delivers 100% more cooling power than the 5,000 BTU device from Example 1 (10 EER).
However, it doesn’t draw 100% more amps. In fact, it draws 67% more amps to achieve a 100% more powerful cooling effect. It is thus more cost-effective.
The only difference is the energy efficiency rating (EER).
You can check out an example of a generator need to power a 5,000 BTU air conditioner here.
Special Example: Battery-Powered Air Conditioners Have Much Higher Draw Significant Amperes
One of the smallest and most convenient AC units are battery-powered ones. The limitation of the batteries are obvious – they can’t produce a high electrical potential. That’s why we don’t deal with 115V. Rather, the battery-powered air conditioners use a parallel connection in order to produce 24V.
The best battery-powered unit – the Zero Breeze Mark 2 – can deliver 2,300 BTU of cooling power with just 24V electrical potential.
That means it needs 27 amps to power the whole AC unit. That is, in comparison, higher amperage than it’s needed to power an 18,000 BTU portable air conditioner (about 13-19 amps).
Advice On Buying Cost-Effective Air Conditioners
In short, you always want to invest in an air conditioner with a higher EER rating. As we’ve seen by comparing Example 1 and Example 2, a higher EER rating can significantly reduce the electricity consumption of an air conditioner.
If you have a question about how many amps does your air conditioner draw, you can check the specification sheet or give us the specs in the comments below and we’ll try to help you figure it out.