How Many Amps Does A 5,000 – 18,000 BTU Conditioner Use?

How many amps do air conditioners use?

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.

Example: Some homeowners 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, air conditioner amperage chart, and how you can calculate how many amps your air conditioner uses.

Table: How Many Amps Do Window, Portable, Mini-Split Air Conditioners Draw

Air Conditioner Capacity Amperage (Estimate) AC Type:
How many amps does a 5,000 BTU air conditioner use? 3.62 – 5.43 Amps Window AC
How many amps does a 6,000 BTU air conditioner use? 4.35 – 6.52 Amps Window AC
How many amps does an 8,000 BTU air conditioner use? 5.80 – 8.70 Amps Window AC, Portable AC
How many amps does a 10,000 BTU air conditioner use? 7.25 – 10.87 Amps Window AC, Portable AC
How many amps does a 12,000 BTU air conditioner use? 8.70 – 13.04 Amps Window AC, Portable AC, Mini-Split Air Conditioner
How many amps does a 15,000 BTU air conditioner use? 10.87 – 16.30 Amps Window AC, Portable AC
How many amps does an 18,000 BTU air conditioner use? 13.04 – 19.57 Amps Window AC, Portable AC, Mini-Split AC

From the table above, it’s evident that window and portable air conditioners can draw anywhere from 3.52 amps to almost 20 amps.

Let’s put those numbers in an air conditioner amperage chart:

Air Conditioner Amperage Chart (From 5,000 BTU To 18,000 BTU)

graph of how many amps 5000, 6000, 8000, 10000, 12000, 15000, 18000 btu air conditioners draw

On the amperage chart above, we have charted the maximum estimated amps, an AC unit of 5,000 – 18,000 BTU is estimated to draw.

Example 1: You can see that the 5,000 BTU unit (be it window AC or portable AC) draws a bit more than 5 A.

Example 2: How many amps does a 12,000 BTU mini-split use? We can see from the air conditioner amperage chart that it draws about 13 A.

Example 3: 18,000 BTU unit draws a little less than 20 A.

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:

  1. From BTU to electrical power (measured in Watts).
  2. 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 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 needed 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 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 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.

19 thoughts on “How Many Amps Does A 5,000 – 18,000 BTU Conditioner Use?”

  1. Could you tell me what the EER is for the RV roof top Coleman NDQ 13500 btu ac? It is also a power saver per the manufacturer. Thanks.

  2. Hi, I’m looking for an ac window unit with 10,000 btu. This will be used only if we needed when we’re out of power. We live where we get a lot of hurricanes. Will be using a 3000 generator. I’ve searched which would be the best ac unit, but I’m stuck with 2. One is an Lg and the other is a Frigidaire. In the details description for both it shows Amperage LG 15 and Frigidaire 8. The combined energy efficiency ratio(CEER) shows for both the same that is a 12. They also provided the Energy Efficiency Ratio (EER) with LG 12.1 and Frigidaire 12. Both are 115 voltage. Wattage LG 820 and Frigidaire 833. Both Energy Star. I want to save on electricity and LG shows a big difference in amperage. How can LG even be energy efficiency with the amps it provides? Which of this two saves me the most? Does it affect the cooling? Weather in Summer can get way over 100’s. Thank you.

    • Hello Ludy, you’re right, the most energy-efficient 10,000 BTU AC would be the best. As far as window AC units are concerned, you can’t get much higher than the 12 EER rating. In short, you’re looking at the right units. Only Midea U Inverter has a higher 15 CEER rating (you can see how energy-efficient the other 10,000 BTU AC units are here).

      The LG and Frigidaire units pretty much have the same energy efficiency (EER about 12 and about 830 max. wattage). That thing with amperage is a bit weird. 8 amps (Frigidaire unit) sounds pretty much OK for 115V. That LG’s 15 amp number is way off. Seems like a typo.

    • Hello Tommy, an 8,000 BTU AC will run on about 1,000W. If your Yamaha generator can generate 2,000W, you can use it to run the 8,000 BTU unit.

  3. Can I run two 5000 btu 115v window air conditioner on a 15 Amp breaker or should I have them on separate amps? Also what type of extension cord would I use if I need to plug it into another outlet that is connected to a 20 Amp breaker? My room and my mom’s room power outlets share 15 Amp breaker. I can run an extension cold to the washer outlet in the bathroom that is on a 20 Amp breaker. I already know not go have my air unit on and the washer going at the same time. Thank you for the help. Oh, this is the air conditioners I’m going to be using Midea 5,000 BTU 115V Window Air Conditioner with Remote, White, MAW05R1WWT

    • Hello Luke, two 5,000 BTU 115V window units running simultaneously will require about 1000W; that translates to about 10 amps. For that, a 15 amp breaker should be sufficient; you will only have problems with the startup voltage that can shoot the amps above 20 amps. The washer will require about 2000W; you have correctly figured out that it’s impossible to run the washer and window AC at the same time.

      For now, you could run both units on a 15 amp breaker. If you see that you have problems (which is rather unlikely given these are very small units), you still can connect two 15 amp breakers. Hope you find this helpful.

  4. I heard air conditioners will draw sometimes twice to three times the amount of power on start up. Is this true? For instance, if I wanted to run a Frederich 15,000 BTU with the following specs: 115 Volts 11 Amps 1270 Watts 11.8 EER

    From what I understand I would need at least something that can handle 22 amps, 2540 Watts? Meaning a 15 amp circuit would be overwhelmed and even a 20 would be as well? I jest in my statement: that seems like a rather niche market. As a 30 amp circuit, to me is what my stove is on. Are there exceptions to this rule? Esp with newer air conditioners? As a layman I appreciate your blog and wonder why the manufacturers don’t list maximum amps needed instead of running amps.

    If you were me would you take a chance in putting said 15,000 btu air conditioner on a 15 amp circuit?

    Thank you for your anticipated response. 😁

    • Hello Handsome Dan, it’s true that AC units have a startup surge. Depending on the unit it can be 1.04 to 2.00 times the running wattage. Now, in the worst case, an 11 amps Frederich 15,000 BTU unit will have a 22 amps surge. But most likely, the max. amps are much lower; below 15 amps.

      You’re right, we don’t have adequate knowledge about these surge wattages/amps because manufacturers don’t really include them in the specification sheets. Hopefully this would change in the future.

      P.S.: Sorry for the late reply, the comments are a bit buggy, trying to fix it.

  5. When u mention draw of AMPs ( 5. Amps ) that’s 5 amps per hour. So a 5 amp ac will pull 5amp hours for every hour. Trying to set up ac on battery and which is better running a inverter or not and how many AH will be required

    • Yes, 5 amp is a continuous draw. For batteries, that will be 5 amp-hours; that’s the more relevant information there. However, you need to take into account voltage as well. What really matters is watt-hours. Usually, you have 120V and 5 amps which equals 600 watts; hence 600 watt-hours. Batteries don’t run on 120V; instead, most of them run on 12V. To achieve 600W at 12V, you will need 50 amps; so the draw would be 500 amp-hours (instead of 5 amp-hours). Watt-hour draw, however, will be the same for 12V and 120V voltage.

  6. Hi, I’m a mathematician so your formula 1 and 2 interests me. I wanted to suggest to use the multiplication symbol for multiplying and the divide symbol for dividing. 13,500 is not equal to 1500 divided by 9.

    Another nice tweak for demonstrating calculations is to have the correct number of digits and decimal places, such as showing 1500 for the number 1500 rather than 15000. Just a nice tweak, so it’s not off by, oh, a factor of 10 or so. Thanks.

    • Hello Shayan, the table is calculated based on two factors; 1) BTU cooling output, 2) EER rating. Based on these two factors, you can calculate the wattage. With known voltage (115V circuit), you can calculate the amps. Hope this helps.

  7. So, first of all this was very interesting for a novice, but I am still confused.. I have a new Window Air Conditioner U shaped by Midea 8000 BTU. ISSUE: The cord is too short to reach the plug in?

    We bought it at Home Depot so they recommended 12/3 … 20 AMP? … 250 volts.
    But the unit is 120 Volts 60HZ says 115 Volts 3 prong 1.8 HP 15 Ceer >1560W. Grounded.
    But Lowe’s said 14 Gauge for AC wattage <1875 with 15 AMPs? Straight T plug Flush to wall.

    Midea said they don't recommend using any extension cord – but if we did it should be higher rated than the recommended on the unit. Your chart for 8000 was no where near that AMPage?

    • Hi Vicki, thanks for all this info. The amps in our article are based on a 115V voltage and 12 EER rating (average window AC unit specs).
      Here are the Midea U-shaped 8,000 BTU unit electrical specs: 115V voltages, 8.78A max. amps, and 710W max. wattage. Here is the full Midea specs sheet.
      If you check the amp draw, we estimate that an 8,000 BTU window AC unit should have 5.80A – 8.70A amps amp draw. The Midea’s 8.78A is a bit out of that range but not by a lot.
      Since all the electric requirements are quite basic (115V AC, 60Hz, below 10A amps, 710W), you can pretty much use standard wires. For comparison, these standard wires all of us have lying around are capable of powering 1,500W space heaters. 710W window AC unit should be a piece of cake. Hope this helps.


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