Air Conditioner Power Consumption: Deciphering The Label

By Nicholas BrownFollow me on Twitter.

Air conditioner power consumption trumps that of most appliances. The power consumption of air conditioners averages 318 watts (hourly, for a 24,000 BTU unit) in most American households. The power draw of a unit that size ranges from 1,800 to 2,500 watts in most cases.

The average is only 318 watts because air conditioning units automatically cycle their compressors on/off as needed throughout the day.

The 318-watt average mentioned (source: U.S. DOE) adds up to 228 kWh per month. That would cost:

Currency: USD.

$27.36 at an electricity rate of $0.12/kWh (this is the average electricity rate in the U.S.).

$45.60 (€41.87) at a rate of $0.20/kWh. $0.20 is a common rate in Europe (many European countries are in the range of $0.19 to $0.25/kWh).

$79.80 at a rate of $0.35/kWh.

$102.60 at a rate of $0.45/kWh.

Power Consumption Calculator

Kompulsa has a power consumption calculator that you can use to calculate the power consumption of various appliances. It can also be used to calculate fuel requirements for a trip and your MPG.

Get it on Google Play

You can also use the browser-based version of it.

The operational cost of an air conditioner is dependent on multiple factors. The key one is the size of the room you’re cooling, and the unit size is dependent on your room size. Look for the unit size that corresponds to the room that you are cooling below (for example: if your room is 500 square feet and is located in the United States, you would skip to the 12,000 BTU section).

If you’re also seeking information on refrigerator power consumption, Kompulsa has a page dedicated to that, with the power consumption data organized by refrigerator size and configuration.

A/C condensing units
Air Conditioner Condensing Units. Image obtained with thanks from chooyutshing on Flickr.

Please note that air conditioner energy usage is heavily influenced by the temperature of your environment and your thermostat temperature. The room size recommendations below were obtained from the U.S. Department of Energy.

The cumulative energy usage and energy cost estimates on this page are estimated and not intended for budgetary purposes. All cost figures on this page refer to electricity cost unless otherwise stated. Use the information provided herein at your own risk.

The power consumption of air conditioners is determined by two factors: Runtime, or compressor speed. In the case of a non-inverter/single speed unit, the compressor speed remains the same at all times and the unit shuts off when the desired temperature is achieved. Power consumption is determined by the unit’s runtime in hours multiplied by its wattage.

The power consumption of inverter air conditioners can be controlled in real time because increasing the thermostat temperature decreases compressor speed, thereby reducing power consumption immediately. To determine the average power consumption of your own air conditioner, you can plug it into an energy use meter.

Table Of Contents
How To Determine Air Conditioner Efficiency.
Are Air Conditioners Expensive To Operate?
Effect Of Air Conditioner Size On Power Consumption.
Power Consumption Of Air Conditioners Ordered By Unit Size.
Power Consumption Of 5,000 BTU Air Conditioners.
Power Consumption Of 9,000 BTU Air Conditioners.
Power Consumption Of 12,000 BTU Air Conditioners.
Power Consumption Of 18,000 BTU Air Conditioners.
Power Consumption of 24,000 BTU Air Conditioners.
Power Consumption of 28,000 BTU Air Conditioners.
Reducing Air Conditioner Energy Usage.
Inverter Air Conditioners Vs Standard Units.

How Does One Determine The Efficiency Of An Air Conditioner?

Fortunately, room air conditioners come with an EER rating. EER means Energy Efficiency Ratio. The EER is the ratio of an A/C unit’s cooling capacity to its wattage. Therefore, a 24,000 BTU [PDF] unit with an EER of 10 draws 2,400 watts (24000 / 2400).

Due to the exceptionally high power consumption of air conditioners, it’s ideal to purchase a unit with an EER above 11. These are easy to find.

The label of an 18,000 BTU air conditioner.

Of all the electrical ratings printed on the label above, the only one relevant to your electric bill is the one marked ‘STD INPUT POWER’. That is the unit’s wattage.

The unit won’t draw as much as the locked rotor current unless it fails to start (due to a locked rotor, that is), and the ‘MAX. INPUT CONSUMPTION’ is the initial startup power consumption. It won’t draw this much current for more than a few seconds, and is therefore irrelevant to your electric bill.

The Capacity Btu/h rating is just the air conditioner’s cooling capacity, measured in BTUs. It indicates that this is an 18,000 BTU unit. We can now conclude that the EER of this unit is 9.47 by dividing the BTU/h rating (18,000) by the standard power input rating (1900). This is common, but not the best. Remember, a higher EER is better!

For environmental reasons, ensure that the refrigerant (marked ‘REFRIG’ on this unit) is R410A, and not R22, as R410A won’t cause ozone layer depletion. Almost all new household air conditioners use R410A, so they are easy to find. R22 units are also getting more expensive to repair because that refrigerant is being phased out/is increasingly scarce.

Are Air Conditioners Expensive To Operate?

Yes, air conditioners are expensive to operate due to their high electricity usage. If you’re only air conditioning one room, the cost of operating an air conditioner would be dramatically lower than if you were air conditioning 3 or more rooms. Room size is also an important factor, but generally — more rooms translates to a higher HVAC bill.

What percentage your air conditioner’s power usage of your overall household energy usage is determined by what kind of appliances you have. For example: If you have minimal lighting (one bulb per room with no recessed lighting), then lighting should account for a lower percentage of your energy usage.

However, if you have several high-wattage incandescent light bulbs per room, that could quickly add up to a massive electric bill. The cost of ownership is determined by how much power the air conditioner uses over time, so this is the cumulative power consumption.

You can reduce energy usage by only turning on the AC in the room that you’re going to spend most of your time in for the day (that could be your home office or bedroom, for example). You’ll survive in the other rooms if you don’t stay in them for long!

Effect Of Unit Size On Air Conditioner Power Consumption

In some cases, very large units have a slightly lower EER (this means that they use more energy) than the average unit. However, smaller air conditioners may end up costing you more due to common habits.

Small units take long to cool off if used in rooms larger than the recommended size, so you may be reluctant to turn them off because you won’t want to wait for them to cool back off later (this is a terrible waste of energy). To avoid waiting, some people may buy slightly larger air conditioners.

Bear in mind that this article is not intended to help you to choose a unit size based on the average efficiency of that size unit. You should skip to the section that corresponds to the unit size required by your room.

Disclaimer: The information provided below is not intended for budgetary purposes, it is estimated. Use it at your own risk.

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If you’re also seeking information on refrigerator power consumption, Kompulsa has a page dedicated to that, with the power consumption data organized by refrigerator size and configuration.

Power Consumption Of Air Conditioners – Ordered By Unit Size

NB: The air conditioner sizing data below does not apply to megathermal climates and assumes 24 hours/day usage.

Power Consumption Of 5,000 BTU Air Conditioners (0.41 Tons/1.4 kW)

5,000 BTU air conditioners are recommended for rooms less than 200 square feet (ideally less than 150 square feet).

The wattage of 5,000 BTU air conditioner units averages 446 to 580 watts (most of the units assessed for this average were window units, as 5,000 BTU split units are uncommon).

People often buy 5,000 BTU air conditioners for college dormitories and small apartments. They are usually window units. People often buy these window air conditioners because they are more DIY-friendly and can be installed without cutting holes in your landlord’s wall.

Estimated Monthly Energy Usage:

51 to 59 kWh

At the U.S. national average electricity rate of $0.12 per kWh, that works out to:

$6.12 to $7.08/Month

Thermostat temperatures above 25 °C are assumed. This does not include inverter air conditioners.

You can find and buy the most energy-efficient 5,000 BTU air conditioners with the help of our air conditioner finder, and it orders units by power consumption!

Power Consumption Of 9,000 BTU Air Conditioners (0.75 Tons/2.6 kW)

The power consumption of 9,000 BTU air conditioner units ranges from 800-900 watts (if a 9,000 BTU A/C unit consumes more than 900 watts, it is inefficient and you should look for a better model). 9,000 BTU A/C units are recommended for rooms that are 350-400 square feet (this average applies to both window and split units).

If you need to purchase a 9,000 BTU air conditioner for a 350-400 square foot room, you might be able to buy a 10,000 BTU or 12,000 BTU air conditioner instead under certain circumstances (please contact a professional to advise you on this), as these will cool your room quicker.

Bear in mind that you should not purchase an oversized unit, as this may compromise the air conditioner’s performance and even promote mold growth due to excessive humidity.

They will not incur a significantly higher electricity cost than smaller units because they don’t need to run as long as the smaller ones (in this case, i’m assuming that you’ll purchase an inverter model). The average energy usage of the common 24,000 BTU air conditioners is slightly higher because they provide fewer BTUs of cooling capacity per watt of energy consumed.

Estimated Monthly Energy Usage:

71 to 95 kWh

At the U.S. national average electricity rate of $0.12 per kWh, that works out to:

$8.52 to $11.40/Month

Thermostat temperatures above 25 °C are assumed. This includes both inverter and non-inverter units.

You can buy 9,000 BTU air conditioners, and find the most energy-efficient units ordered by energy usage with the help of our air conditioner finder.

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Power Consumption Of 12,000 BTU Air Conditioners (1 Ton/3.5 kW)

12,000 BTU air conditioner units consume 991 (EER: 12.1) to 1,333 watts (EER: 9, which is a bit low for these units, by today’s standards). An EER of 11.3 is average for new 12,000 BTU window units, translating to a wattage of 1,061 Watts.

Please don’t buy air conditioners with an EER below 11 (in other words, don’t buy anything with a wattage exceeding 1,090 Watts) if you’re shopping for a 12,000 BTU unit. A/C units with an EER of 12 are so common that you won’t have any trouble finding them. There are units with EERs greater than 11 for well under $800 USD. Your wallet will thank you later.

Try Kompulsa’s energy usage calculator.

12,000 BTU units are recommended for rooms ranging from 450-550 square feet.

Also Read: Heater Power Consumption, Ordered By Unit Size.

Estimated Monthly Energy Usage:

92 to 122 kWh

At the U.S. national average electricity rate of $0.12 per kWh, that works out to:

$11.04 to $14.64/Month

Thermostat temperatures above 25 °C are assumed. This includes both inverter and non-inverter units.

You can buy 12,000 BTU air conditioners, or just browse them ordered by energy usage with the help of our air conditioner finder.

Electrical Ratings

The amperage of 12,000 BTU units I checked ranged from 3.5 to 5.1 amps (these current ratings were obtained from the specifications of five different 220 volt models, including both inverter and non-inverter air conditioners).

Power Consumption Of 18,000 BTU Air Conditioners (1.5 Tons/5.2 kW)

There are uncommon air conditioner sizes in the 12,000 to 18,000 BTU range, including 13,000 BTU, 14,000 BTU, 15,000 BTU, and room size calculations sometimes yield results that don’t match any unit (or extremely rare units) on the market (such as 16,000 BTU).

In such cases, your installer might recommend a slightly (or even considerably) larger unit (such as an 18,000 BTU unit) if that’s all they can find.

The power consumption of 1.5 ton air conditioners typically ranges from 1,470 watts to 1,614 watts, and have EERs ranging from 11 to a little over 12.

Always remember that this isn’t the units’ cumulative power consumption, this is the wattage (if they are operating at their maximum settings. i.e. their lowest temperature setting and highest fan setting). The EER is normally printed on the yellow energy label, if any.

Always go for the best! EERs in the 12 range aren’t too hard to find, so buy air conditioners with an EER exceeding 12, if possible. The difference between 11 and 12 isn’t particularly significant, though, so be sure to get a unit that is offered with solid support (this entails buying it from a reputable store that offers free repairs within a reasonable warranty period).

Fortunately, there are inverter air conditioners in this price range, and inverter units are capable of consuming 50%-60% less energy than their non-inverter counterparts under some circumstances (your chances of saving that much increase if you’re a regular A/C user).

If you’re also seeking information on refrigerator power consumption, Kompulsa has a page dedicated to that, with the power consumption data organized by refrigerator size and configuration.

Estimated Monthly Energy Usage:

169 to 185 kWh

At the U.S. national average electricity rate of $0.12 per kWh, that works out to:

$20.28 to $22.20/Month.

Thermostat temperatures above 25 °C are assumed. This includes both inverter and non-inverter units.

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Power Consumption Of 24,000 BTU Air Conditioners (2 Tons/7 kW)

24,000 BTU A/C units are a little less efficient than their smaller counterparts, with an EER range of 8.5 to 12.5 for new units (this applies to both split and window units).

They typically draw 2,500 to 2,823 watts. Despite their relatively-low efficiency, these units are among the most widely used (possibly because they cool rooms very quickly, as well as the popularity of the open floor plans).

You can determine and average the power consumption of your air conditioner using a ‘Kill A Watt’ or similar energy use monitor and compare its energy usage to that of modern units, as well as the figures provided herein.

For that reason, they are still a good option (not that you have much of a choice, as some rooms require units of this size). People with smaller units may not want to turn them off because they might take too long to cool back off when they return.

Try Kompulsa’s energy usage calculator.

This means that the energy usage of a 24,000 BTU air conditioner could, in practice, be lower than that of a 12,000 BTU unit (assuming it is used in the same room).

In the United States, the power consumption of 24,000 BTU household air conditioner units averages 228 kWh/month (according to the Department Of Energy), and these units are recommended for rooms ranging from 1,400-1,500 square feet, but that isn’t a requirement. These units can be used in smaller rooms.

This amounts to an average cost of $27 USD/month. An inverter air conditioner might provide energy savings up to 60%, depending on the circumstances.

Also Read: Heater Power Consumption, Ordered By Unit Size.

Electrical Ratings

The current rating of 24,000 BTU air conditioners is often in the range of 8.4 amps to 12.7 amps. This data was obtained from the labels of six 220 volt units of the following brands: Pioneer, Senville, General Electric, Friederich, Haier, and LG.

You can find the most efficient 24,000 BTU units (sorted by monthly energy usage) using our air conditioner finder. It also provides a (rough) monthly electricity cost estimate. You can also purchase the air conditioners using the links provided.

Power Consumption Of 28,000 BTU Air Conditioners (2.3 Tons/8.2 kW)

28,000 BTU units are intended to cool rooms up to 1,900 square feet (bear in mind, that this does not include rooms in megathermal/tropical climates).

These units are typically in the 9-10 EER range, so the wattage of most of 28,000 BTU units ranges from 2,800 watts to 3,100 watts. As is the case with the 24,000 BTU, the EER of these units is not the best, but larger units do tend to have lower EER ratings than the smaller ones.

The best thing you can do efficiency-wise is to find the highest EER for the unit which matches your room best. This means that if your room needs 28,000 BTU, you should still get a 28,000 BTU unit, but just find the most efficient 28,000 BTU unit you can.

One way to do that is to check the listings for those units on our appliance finder, which sorts units by their electricity consumption, and provides a monthly power cost estimate.

Estimated Monthly Energy Usage:

330 to 357 kWh

At the U.S. national average electricity rate of $0.12 per kWh, that works out to:

$39.60 to $42.84/Month.

Thermostat temperatures above 25 °C are assumed. This includes both inverter and non-inverter units.

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Reducing Air Conditioner Energy Usage/Cooling On A Budget

After seeing the power consumption data above, you may be concerned about the high energy usage of air conditioners, but don’t worry — This can be reduced substantially with the following tips (which are intended specifically for residential air conditioners, although they may be helpful in other cases).


Air conditioners have to pass air through many tiny crevices in order to operate efficiently. Ensure that your filters are clean, as well as your condenser and evaporator fins. If any of the following parts are dirty, airflow may be compromised.

Installation of an air conditioner's condensing unit.
Air conditioner installation. Image credit:

A clogged condenser with inadequate airflow may overheat, reduce its ability to dispel heat outside (decreasing efficiency), and damage the compressor. A congested evaporator may freeze, dramatically reducing efficiency and rendering your air conditioner a paperweight. Clearing an obstructed evaporator can reduce air conditioner power consumption.

The same applies to the filters. The condenser and evaporator are not user serviceable, so it’s highly recommended that you call a contractor to clean them for you.

Inverter Air Conditioners Vs Standard Units

Standard air conditioners switch on at full speed (resulting in higher noise levels), cool the air, and then shut themselves off. You can set your thermostat temperature, so they will cycle on and off as needed to maintain that temperature.

Inverter units, on the other hand, adjust the speed of their compressors in response to cooling demand using techniques and technologies such as PWM and variable frequency drives (learn about PWM from Kompulsa’s PWM guide).

Some inverter air conditioners have variable speed fans which utilize the same PWM motor control technology. PWM enables them to operate at low speeds (which results in low power consumption, and low noise levels) when cooling demand is low, and they don’t have to operate at full speed all the time.

You can also adjust the temperature of the room fairly quickly with inverter units, as the until will turn itself down immediately (but it will take a moment for the room temperature to change).

When An Inverter Air Conditioner Is Not Worth It

If you rarely use or need your air conditioner, you won’t recuperate the extra funds spent on an inverter unit easily, if at all.

Scenarios in which you should buy standard air conditioners

You virtually (or actually) live at work.

You live on a plane. Some people travel so frequently that they only go home once in a while.

When An Inverter Air Conditioner Is Worth It

Inverter air conditioners provide a more convenient temperature control option that enables you to turn the unit up or down quickly without it cycling on and off all the time. In general, an inverter air conditioner will pay for itself most quickly if you normally use your air conditioner for extended time periods.

According to various manufacturers, the power consumption of inverter air conditioners can be 50-70% less than their non-inverter counterparts. This makes them more than worthwhile in regions with extremely high electricity prices exceeding $0.20/kWh, while savings are more modest (but still high) in regions with electricity prices below $0.10/kWh).

Also Read: Heater Power Consumption, Ordered By Unit Size.

Example scenarios in which you should buy inverter air conditioners, and in which they are most likely to pay for themselves in a reasonable time period

You spend more than 8 hours per day at home.

Your working hours are typical. This includes 9-5 jobs, as well as all night shifts, assuming that you’re at home in the days.

Buy White Curtains

White curtains can reflect a significant amount of hot sunlight back outside. Sunlight turns into heat after it enters your room, and having direct sunlight on you can make matters much worse.

Insulate Your House – The Most Effective Option

Installing insulation can dramatically reduce air conditioner power consumption by keeping heat out. Inversely, household insulation can also reduce heater energy usage during winter by keeping the cold air outside from leeching the heat out of your house. Insulation operates by impeding the transfer of heat into or out of the house.

Insulation R-Value: The R-value of insulation is a measure of how effective it is. The higher the R-value, the greater the effect it will have on your electric bill.

Use A Fan

Buy a standing fan and point it at yourself. Turning up your air conditioner thermostat temperature (substantially) will help you cool down using the evaporative cooling effect that fans provide. Only turn on the fan if you are going to compensate for its power consumption by turning up the thermostat temperature.

For large rooms, I would recommend a standing fan which is at least 16″, but no more than 20″ to keep noise levels and power consumption down. If you don’t point the fan at yourself, it won’t be very helpful. If you don’t like having a fan blow on you all the time, set it to oscillate. The energy usage of the fans in the range I recommended is usually 50-100 watts.

For smaller rooms, there are desk fans well under 16″ (you’ll most often see 8″ ones), which may be adequate if you use them on your desk (right beside you) as intended, or if your room is just slightly too warm. I find these convenient because I can just pick them up and carry them to whichever room i’m going to.


A sturdy awning installation can block quite a bit of sunlight, which would otherwise heat up your house quite a bit. This can significantly reduce the load on your air conditioner, hence lowering your electric bill.

Point The A/C Vent At Yourself, And Turn Up The Thermostat Temperature

This worked incredibly well for me. If possible, pointing the A/C vent at yourself is a way to take advantage of the energy-efficient evaporative cooling effect that fans provide, and the A/C unit will dedicate a greater percentage of its capacity to cooling you, rather than wasting it on the furniture in the room.

This is possibly one of the riskier options. The unit must be kept very clean for your safety.

Set The Thermostat Temperature Wisely

Increase the temperature on your thermostat as much as you comfortably can. The lower it is, the longer the unit has to stay on to maintain that temperature. If you’re using an inverter unit, then the lower the thermostat temperature setting is, the faster the compressor has to pump refrigerant, increasing power consumption. You could waste 16% more energy for every degree (Celsius) that you turn down your thermostat temperature below 25 °C, or 8% more for every degree Fahrenheit you turn it down below 78 °F.

Cool Only The Areas You Need To

If you have a unit in every room, or central A/C, it may be tempting to ‘keep the house cool’, as some would put it, but that is costly. Try your best to turn on the A/C only in the room that you’re currently in, and don’t turn it on if you’ll only be in the room for a few minutes, because all that energy that went into cooling it off would go to waste.

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Further Reading

Save money on cooling with these tips.